Now that OBJT_DEFAULT objects can't be instantiated, we can simplify checks of the form object->type == OBJT_DEFAULT || (object->flags & OBJ_SWAP) != 0. No functional change intended. Reviewed by: alc, kib Tested by: pho Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D35788
2420 lines
69 KiB
C
2420 lines
69 KiB
C
/*-
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* SPDX-License-Identifier: (BSD-4-Clause AND MIT-CMU)
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*
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* Copyright (c) 1991 Regents of the University of California.
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* All rights reserved.
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* Copyright (c) 1994 John S. Dyson
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* All rights reserved.
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* Copyright (c) 1994 David Greenman
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* All rights reserved.
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* Copyright (c) 2005 Yahoo! Technologies Norway AS
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* All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* The Mach Operating System project at Carnegie-Mellon University.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
|
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
|
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* from: @(#)vm_pageout.c 7.4 (Berkeley) 5/7/91
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*
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*
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* Copyright (c) 1987, 1990 Carnegie-Mellon University.
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* All rights reserved.
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*
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* Authors: Avadis Tevanian, Jr., Michael Wayne Young
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*
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* Permission to use, copy, modify and distribute this software and
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* its documentation is hereby granted, provided that both the copyright
|
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* notice and this permission notice appear in all copies of the
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* software, derivative works or modified versions, and any portions
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* thereof, and that both notices appear in supporting documentation.
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*
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* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
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* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
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* FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
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*
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* Carnegie Mellon requests users of this software to return to
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*
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* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
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* School of Computer Science
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* Carnegie Mellon University
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* Pittsburgh PA 15213-3890
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*
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* any improvements or extensions that they make and grant Carnegie the
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* rights to redistribute these changes.
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*/
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/*
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* The proverbial page-out daemon.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include "opt_vm.h"
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/kernel.h>
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#include <sys/blockcount.h>
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#include <sys/eventhandler.h>
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#include <sys/lock.h>
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#include <sys/mutex.h>
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#include <sys/proc.h>
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#include <sys/kthread.h>
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#include <sys/ktr.h>
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#include <sys/mount.h>
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#include <sys/racct.h>
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|
#include <sys/resourcevar.h>
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#include <sys/sched.h>
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|
#include <sys/sdt.h>
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#include <sys/signalvar.h>
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|
#include <sys/smp.h>
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|
#include <sys/time.h>
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#include <sys/vnode.h>
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#include <sys/vmmeter.h>
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#include <sys/rwlock.h>
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#include <sys/sx.h>
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#include <sys/sysctl.h>
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#include <vm/vm.h>
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#include <vm/vm_param.h>
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#include <vm/vm_object.h>
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#include <vm/vm_page.h>
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#include <vm/vm_map.h>
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#include <vm/vm_pageout.h>
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#include <vm/vm_pager.h>
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#include <vm/vm_phys.h>
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#include <vm/vm_pagequeue.h>
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#include <vm/swap_pager.h>
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#include <vm/vm_extern.h>
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#include <vm/uma.h>
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|
|
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/*
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* System initialization
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*/
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|
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/* the kernel process "vm_pageout"*/
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static void vm_pageout(void);
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static void vm_pageout_init(void);
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static int vm_pageout_clean(vm_page_t m, int *numpagedout);
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static int vm_pageout_cluster(vm_page_t m);
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static void vm_pageout_mightbe_oom(struct vm_domain *vmd, int page_shortage,
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int starting_page_shortage);
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|
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SYSINIT(pagedaemon_init, SI_SUB_KTHREAD_PAGE, SI_ORDER_FIRST, vm_pageout_init,
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NULL);
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struct proc *pageproc;
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static struct kproc_desc page_kp = {
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"pagedaemon",
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vm_pageout,
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&pageproc
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};
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SYSINIT(pagedaemon, SI_SUB_KTHREAD_PAGE, SI_ORDER_SECOND, kproc_start,
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&page_kp);
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SDT_PROVIDER_DEFINE(vm);
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SDT_PROBE_DEFINE(vm, , , vm__lowmem_scan);
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|
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/* Pagedaemon activity rates, in subdivisions of one second. */
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#define VM_LAUNDER_RATE 10
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#define VM_INACT_SCAN_RATE 10
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|
|
static int swapdev_enabled;
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int vm_pageout_page_count = 32;
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|
|
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static int vm_panic_on_oom = 0;
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SYSCTL_INT(_vm, OID_AUTO, panic_on_oom,
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CTLFLAG_RWTUN, &vm_panic_on_oom, 0,
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"Panic on the given number of out-of-memory errors instead of "
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"killing the largest process");
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|
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static int vm_pageout_update_period;
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SYSCTL_INT(_vm, OID_AUTO, pageout_update_period,
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CTLFLAG_RWTUN, &vm_pageout_update_period, 0,
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"Maximum active LRU update period");
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|
|
|
static int pageout_cpus_per_thread = 16;
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SYSCTL_INT(_vm, OID_AUTO, pageout_cpus_per_thread, CTLFLAG_RDTUN,
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&pageout_cpus_per_thread, 0,
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"Number of CPUs per pagedaemon worker thread");
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|
|
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static int lowmem_period = 10;
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SYSCTL_INT(_vm, OID_AUTO, lowmem_period, CTLFLAG_RWTUN, &lowmem_period, 0,
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"Low memory callback period");
|
|
|
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static int disable_swap_pageouts;
|
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SYSCTL_INT(_vm, OID_AUTO, disable_swapspace_pageouts,
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CTLFLAG_RWTUN, &disable_swap_pageouts, 0,
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"Disallow swapout of dirty pages");
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|
|
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static int pageout_lock_miss;
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SYSCTL_INT(_vm, OID_AUTO, pageout_lock_miss,
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CTLFLAG_RD, &pageout_lock_miss, 0,
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"vget() lock misses during pageout");
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|
|
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static int vm_pageout_oom_seq = 12;
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SYSCTL_INT(_vm, OID_AUTO, pageout_oom_seq,
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CTLFLAG_RWTUN, &vm_pageout_oom_seq, 0,
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|
"back-to-back calls to oom detector to start OOM");
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|
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static int act_scan_laundry_weight = 3;
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SYSCTL_INT(_vm, OID_AUTO, act_scan_laundry_weight, CTLFLAG_RWTUN,
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&act_scan_laundry_weight, 0,
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"weight given to clean vs. dirty pages in active queue scans");
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static u_int vm_background_launder_rate = 4096;
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SYSCTL_UINT(_vm, OID_AUTO, background_launder_rate, CTLFLAG_RWTUN,
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&vm_background_launder_rate, 0,
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"background laundering rate, in kilobytes per second");
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static u_int vm_background_launder_max = 20 * 1024;
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SYSCTL_UINT(_vm, OID_AUTO, background_launder_max, CTLFLAG_RWTUN,
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&vm_background_launder_max, 0,
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"background laundering cap, in kilobytes");
|
|
|
|
u_long vm_page_max_user_wired;
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SYSCTL_ULONG(_vm, OID_AUTO, max_user_wired, CTLFLAG_RW,
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&vm_page_max_user_wired, 0,
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|
"system-wide limit to user-wired page count");
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static u_int isqrt(u_int num);
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static int vm_pageout_launder(struct vm_domain *vmd, int launder,
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bool in_shortfall);
|
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static void vm_pageout_laundry_worker(void *arg);
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struct scan_state {
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struct vm_batchqueue bq;
|
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struct vm_pagequeue *pq;
|
|
vm_page_t marker;
|
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int maxscan;
|
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int scanned;
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};
|
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|
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static void
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vm_pageout_init_scan(struct scan_state *ss, struct vm_pagequeue *pq,
|
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vm_page_t marker, vm_page_t after, int maxscan)
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|
{
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|
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vm_pagequeue_assert_locked(pq);
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KASSERT((marker->a.flags & PGA_ENQUEUED) == 0,
|
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("marker %p already enqueued", marker));
|
|
|
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if (after == NULL)
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TAILQ_INSERT_HEAD(&pq->pq_pl, marker, plinks.q);
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else
|
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TAILQ_INSERT_AFTER(&pq->pq_pl, after, marker, plinks.q);
|
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vm_page_aflag_set(marker, PGA_ENQUEUED);
|
|
|
|
vm_batchqueue_init(&ss->bq);
|
|
ss->pq = pq;
|
|
ss->marker = marker;
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ss->maxscan = maxscan;
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ss->scanned = 0;
|
|
vm_pagequeue_unlock(pq);
|
|
}
|
|
|
|
static void
|
|
vm_pageout_end_scan(struct scan_state *ss)
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|
{
|
|
struct vm_pagequeue *pq;
|
|
|
|
pq = ss->pq;
|
|
vm_pagequeue_assert_locked(pq);
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|
KASSERT((ss->marker->a.flags & PGA_ENQUEUED) != 0,
|
|
("marker %p not enqueued", ss->marker));
|
|
|
|
TAILQ_REMOVE(&pq->pq_pl, ss->marker, plinks.q);
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vm_page_aflag_clear(ss->marker, PGA_ENQUEUED);
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pq->pq_pdpages += ss->scanned;
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}
|
|
|
|
/*
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|
* Add a small number of queued pages to a batch queue for later processing
|
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* without the corresponding queue lock held. The caller must have enqueued a
|
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* marker page at the desired start point for the scan. Pages will be
|
|
* physically dequeued if the caller so requests. Otherwise, the returned
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* batch may contain marker pages, and it is up to the caller to handle them.
|
|
*
|
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* When processing the batch queue, vm_pageout_defer() must be used to
|
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* determine whether the page has been logically dequeued since the batch was
|
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* collected.
|
|
*/
|
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static __always_inline void
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vm_pageout_collect_batch(struct scan_state *ss, const bool dequeue)
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|
{
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struct vm_pagequeue *pq;
|
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vm_page_t m, marker, n;
|
|
|
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marker = ss->marker;
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pq = ss->pq;
|
|
|
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KASSERT((marker->a.flags & PGA_ENQUEUED) != 0,
|
|
("marker %p not enqueued", ss->marker));
|
|
|
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vm_pagequeue_lock(pq);
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for (m = TAILQ_NEXT(marker, plinks.q); m != NULL &&
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ss->scanned < ss->maxscan && ss->bq.bq_cnt < VM_BATCHQUEUE_SIZE;
|
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m = n, ss->scanned++) {
|
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n = TAILQ_NEXT(m, plinks.q);
|
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if ((m->flags & PG_MARKER) == 0) {
|
|
KASSERT((m->a.flags & PGA_ENQUEUED) != 0,
|
|
("page %p not enqueued", m));
|
|
KASSERT((m->flags & PG_FICTITIOUS) == 0,
|
|
("Fictitious page %p cannot be in page queue", m));
|
|
KASSERT((m->oflags & VPO_UNMANAGED) == 0,
|
|
("Unmanaged page %p cannot be in page queue", m));
|
|
} else if (dequeue)
|
|
continue;
|
|
|
|
(void)vm_batchqueue_insert(&ss->bq, m);
|
|
if (dequeue) {
|
|
TAILQ_REMOVE(&pq->pq_pl, m, plinks.q);
|
|
vm_page_aflag_clear(m, PGA_ENQUEUED);
|
|
}
|
|
}
|
|
TAILQ_REMOVE(&pq->pq_pl, marker, plinks.q);
|
|
if (__predict_true(m != NULL))
|
|
TAILQ_INSERT_BEFORE(m, marker, plinks.q);
|
|
else
|
|
TAILQ_INSERT_TAIL(&pq->pq_pl, marker, plinks.q);
|
|
if (dequeue)
|
|
vm_pagequeue_cnt_add(pq, -ss->bq.bq_cnt);
|
|
vm_pagequeue_unlock(pq);
|
|
}
|
|
|
|
/*
|
|
* Return the next page to be scanned, or NULL if the scan is complete.
|
|
*/
|
|
static __always_inline vm_page_t
|
|
vm_pageout_next(struct scan_state *ss, const bool dequeue)
|
|
{
|
|
|
|
if (ss->bq.bq_cnt == 0)
|
|
vm_pageout_collect_batch(ss, dequeue);
|
|
return (vm_batchqueue_pop(&ss->bq));
|
|
}
|
|
|
|
/*
|
|
* Determine whether processing of a page should be deferred and ensure that any
|
|
* outstanding queue operations are processed.
|
|
*/
|
|
static __always_inline bool
|
|
vm_pageout_defer(vm_page_t m, const uint8_t queue, const bool enqueued)
|
|
{
|
|
vm_page_astate_t as;
|
|
|
|
as = vm_page_astate_load(m);
|
|
if (__predict_false(as.queue != queue ||
|
|
((as.flags & PGA_ENQUEUED) != 0) != enqueued))
|
|
return (true);
|
|
if ((as.flags & PGA_QUEUE_OP_MASK) != 0) {
|
|
vm_page_pqbatch_submit(m, queue);
|
|
return (true);
|
|
}
|
|
return (false);
|
|
}
|
|
|
|
/*
|
|
* Scan for pages at adjacent offsets within the given page's object that are
|
|
* eligible for laundering, form a cluster of these pages and the given page,
|
|
* and launder that cluster.
|
|
*/
|
|
static int
|
|
vm_pageout_cluster(vm_page_t m)
|
|
{
|
|
vm_object_t object;
|
|
vm_page_t mc[2 * vm_pageout_page_count], p, pb, ps;
|
|
vm_pindex_t pindex;
|
|
int ib, is, page_base, pageout_count;
|
|
|
|
object = m->object;
|
|
VM_OBJECT_ASSERT_WLOCKED(object);
|
|
pindex = m->pindex;
|
|
|
|
vm_page_assert_xbusied(m);
|
|
|
|
mc[vm_pageout_page_count] = pb = ps = m;
|
|
pageout_count = 1;
|
|
page_base = vm_pageout_page_count;
|
|
ib = 1;
|
|
is = 1;
|
|
|
|
/*
|
|
* We can cluster only if the page is not clean, busy, or held, and
|
|
* the page is in the laundry queue.
|
|
*
|
|
* During heavy mmap/modification loads the pageout
|
|
* daemon can really fragment the underlying file
|
|
* due to flushing pages out of order and not trying to
|
|
* align the clusters (which leaves sporadic out-of-order
|
|
* holes). To solve this problem we do the reverse scan
|
|
* first and attempt to align our cluster, then do a
|
|
* forward scan if room remains.
|
|
*/
|
|
more:
|
|
while (ib != 0 && pageout_count < vm_pageout_page_count) {
|
|
if (ib > pindex) {
|
|
ib = 0;
|
|
break;
|
|
}
|
|
if ((p = vm_page_prev(pb)) == NULL ||
|
|
vm_page_tryxbusy(p) == 0) {
|
|
ib = 0;
|
|
break;
|
|
}
|
|
if (vm_page_wired(p)) {
|
|
ib = 0;
|
|
vm_page_xunbusy(p);
|
|
break;
|
|
}
|
|
vm_page_test_dirty(p);
|
|
if (p->dirty == 0) {
|
|
ib = 0;
|
|
vm_page_xunbusy(p);
|
|
break;
|
|
}
|
|
if (!vm_page_in_laundry(p) || !vm_page_try_remove_write(p)) {
|
|
vm_page_xunbusy(p);
|
|
ib = 0;
|
|
break;
|
|
}
|
|
mc[--page_base] = pb = p;
|
|
++pageout_count;
|
|
++ib;
|
|
|
|
/*
|
|
* We are at an alignment boundary. Stop here, and switch
|
|
* directions. Do not clear ib.
|
|
*/
|
|
if ((pindex - (ib - 1)) % vm_pageout_page_count == 0)
|
|
break;
|
|
}
|
|
while (pageout_count < vm_pageout_page_count &&
|
|
pindex + is < object->size) {
|
|
if ((p = vm_page_next(ps)) == NULL ||
|
|
vm_page_tryxbusy(p) == 0)
|
|
break;
|
|
if (vm_page_wired(p)) {
|
|
vm_page_xunbusy(p);
|
|
break;
|
|
}
|
|
vm_page_test_dirty(p);
|
|
if (p->dirty == 0) {
|
|
vm_page_xunbusy(p);
|
|
break;
|
|
}
|
|
if (!vm_page_in_laundry(p) || !vm_page_try_remove_write(p)) {
|
|
vm_page_xunbusy(p);
|
|
break;
|
|
}
|
|
mc[page_base + pageout_count] = ps = p;
|
|
++pageout_count;
|
|
++is;
|
|
}
|
|
|
|
/*
|
|
* If we exhausted our forward scan, continue with the reverse scan
|
|
* when possible, even past an alignment boundary. This catches
|
|
* boundary conditions.
|
|
*/
|
|
if (ib != 0 && pageout_count < vm_pageout_page_count)
|
|
goto more;
|
|
|
|
return (vm_pageout_flush(&mc[page_base], pageout_count,
|
|
VM_PAGER_PUT_NOREUSE, 0, NULL, NULL));
|
|
}
|
|
|
|
/*
|
|
* vm_pageout_flush() - launder the given pages
|
|
*
|
|
* The given pages are laundered. Note that we setup for the start of
|
|
* I/O ( i.e. busy the page ), mark it read-only, and bump the object
|
|
* reference count all in here rather then in the parent. If we want
|
|
* the parent to do more sophisticated things we may have to change
|
|
* the ordering.
|
|
*
|
|
* Returned runlen is the count of pages between mreq and first
|
|
* page after mreq with status VM_PAGER_AGAIN.
|
|
* *eio is set to TRUE if pager returned VM_PAGER_ERROR or VM_PAGER_FAIL
|
|
* for any page in runlen set.
|
|
*/
|
|
int
|
|
vm_pageout_flush(vm_page_t *mc, int count, int flags, int mreq, int *prunlen,
|
|
boolean_t *eio)
|
|
{
|
|
vm_object_t object = mc[0]->object;
|
|
int pageout_status[count];
|
|
int numpagedout = 0;
|
|
int i, runlen;
|
|
|
|
VM_OBJECT_ASSERT_WLOCKED(object);
|
|
|
|
/*
|
|
* Initiate I/O. Mark the pages shared busy and verify that they're
|
|
* valid and read-only.
|
|
*
|
|
* We do not have to fixup the clean/dirty bits here... we can
|
|
* allow the pager to do it after the I/O completes.
|
|
*
|
|
* NOTE! mc[i]->dirty may be partial or fragmented due to an
|
|
* edge case with file fragments.
|
|
*/
|
|
for (i = 0; i < count; i++) {
|
|
KASSERT(vm_page_all_valid(mc[i]),
|
|
("vm_pageout_flush: partially invalid page %p index %d/%d",
|
|
mc[i], i, count));
|
|
KASSERT((mc[i]->a.flags & PGA_WRITEABLE) == 0,
|
|
("vm_pageout_flush: writeable page %p", mc[i]));
|
|
vm_page_busy_downgrade(mc[i]);
|
|
}
|
|
vm_object_pip_add(object, count);
|
|
|
|
vm_pager_put_pages(object, mc, count, flags, pageout_status);
|
|
|
|
runlen = count - mreq;
|
|
if (eio != NULL)
|
|
*eio = FALSE;
|
|
for (i = 0; i < count; i++) {
|
|
vm_page_t mt = mc[i];
|
|
|
|
KASSERT(pageout_status[i] == VM_PAGER_PEND ||
|
|
!pmap_page_is_write_mapped(mt),
|
|
("vm_pageout_flush: page %p is not write protected", mt));
|
|
switch (pageout_status[i]) {
|
|
case VM_PAGER_OK:
|
|
/*
|
|
* The page may have moved since laundering started, in
|
|
* which case it should be left alone.
|
|
*/
|
|
if (vm_page_in_laundry(mt))
|
|
vm_page_deactivate_noreuse(mt);
|
|
/* FALLTHROUGH */
|
|
case VM_PAGER_PEND:
|
|
numpagedout++;
|
|
break;
|
|
case VM_PAGER_BAD:
|
|
/*
|
|
* The page is outside the object's range. We pretend
|
|
* that the page out worked and clean the page, so the
|
|
* changes will be lost if the page is reclaimed by
|
|
* the page daemon.
|
|
*/
|
|
vm_page_undirty(mt);
|
|
if (vm_page_in_laundry(mt))
|
|
vm_page_deactivate_noreuse(mt);
|
|
break;
|
|
case VM_PAGER_ERROR:
|
|
case VM_PAGER_FAIL:
|
|
/*
|
|
* If the page couldn't be paged out to swap because the
|
|
* pager wasn't able to find space, place the page in
|
|
* the PQ_UNSWAPPABLE holding queue. This is an
|
|
* optimization that prevents the page daemon from
|
|
* wasting CPU cycles on pages that cannot be reclaimed
|
|
* because no swap device is configured.
|
|
*
|
|
* Otherwise, reactivate the page so that it doesn't
|
|
* clog the laundry and inactive queues. (We will try
|
|
* paging it out again later.)
|
|
*/
|
|
if ((object->flags & OBJ_SWAP) != 0 &&
|
|
pageout_status[i] == VM_PAGER_FAIL) {
|
|
vm_page_unswappable(mt);
|
|
numpagedout++;
|
|
} else
|
|
vm_page_activate(mt);
|
|
if (eio != NULL && i >= mreq && i - mreq < runlen)
|
|
*eio = TRUE;
|
|
break;
|
|
case VM_PAGER_AGAIN:
|
|
if (i >= mreq && i - mreq < runlen)
|
|
runlen = i - mreq;
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* If the operation is still going, leave the page busy to
|
|
* block all other accesses. Also, leave the paging in
|
|
* progress indicator set so that we don't attempt an object
|
|
* collapse.
|
|
*/
|
|
if (pageout_status[i] != VM_PAGER_PEND) {
|
|
vm_object_pip_wakeup(object);
|
|
vm_page_sunbusy(mt);
|
|
}
|
|
}
|
|
if (prunlen != NULL)
|
|
*prunlen = runlen;
|
|
return (numpagedout);
|
|
}
|
|
|
|
static void
|
|
vm_pageout_swapon(void *arg __unused, struct swdevt *sp __unused)
|
|
{
|
|
|
|
atomic_store_rel_int(&swapdev_enabled, 1);
|
|
}
|
|
|
|
static void
|
|
vm_pageout_swapoff(void *arg __unused, struct swdevt *sp __unused)
|
|
{
|
|
|
|
if (swap_pager_nswapdev() == 1)
|
|
atomic_store_rel_int(&swapdev_enabled, 0);
|
|
}
|
|
|
|
/*
|
|
* Attempt to acquire all of the necessary locks to launder a page and
|
|
* then call through the clustering layer to PUTPAGES. Wait a short
|
|
* time for a vnode lock.
|
|
*
|
|
* Requires the page and object lock on entry, releases both before return.
|
|
* Returns 0 on success and an errno otherwise.
|
|
*/
|
|
static int
|
|
vm_pageout_clean(vm_page_t m, int *numpagedout)
|
|
{
|
|
struct vnode *vp;
|
|
struct mount *mp;
|
|
vm_object_t object;
|
|
vm_pindex_t pindex;
|
|
int error;
|
|
|
|
object = m->object;
|
|
VM_OBJECT_ASSERT_WLOCKED(object);
|
|
error = 0;
|
|
vp = NULL;
|
|
mp = NULL;
|
|
|
|
/*
|
|
* The object is already known NOT to be dead. It
|
|
* is possible for the vget() to block the whole
|
|
* pageout daemon, but the new low-memory handling
|
|
* code should prevent it.
|
|
*
|
|
* We can't wait forever for the vnode lock, we might
|
|
* deadlock due to a vn_read() getting stuck in
|
|
* vm_wait while holding this vnode. We skip the
|
|
* vnode if we can't get it in a reasonable amount
|
|
* of time.
|
|
*/
|
|
if (object->type == OBJT_VNODE) {
|
|
vm_page_xunbusy(m);
|
|
vp = object->handle;
|
|
if (vp->v_type == VREG &&
|
|
vn_start_write(vp, &mp, V_NOWAIT) != 0) {
|
|
mp = NULL;
|
|
error = EDEADLK;
|
|
goto unlock_all;
|
|
}
|
|
KASSERT(mp != NULL,
|
|
("vp %p with NULL v_mount", vp));
|
|
vm_object_reference_locked(object);
|
|
pindex = m->pindex;
|
|
VM_OBJECT_WUNLOCK(object);
|
|
if (vget(vp, vn_lktype_write(NULL, vp) | LK_TIMELOCK) != 0) {
|
|
vp = NULL;
|
|
error = EDEADLK;
|
|
goto unlock_mp;
|
|
}
|
|
VM_OBJECT_WLOCK(object);
|
|
|
|
/*
|
|
* Ensure that the object and vnode were not disassociated
|
|
* while locks were dropped.
|
|
*/
|
|
if (vp->v_object != object) {
|
|
error = ENOENT;
|
|
goto unlock_all;
|
|
}
|
|
|
|
/*
|
|
* While the object was unlocked, the page may have been:
|
|
* (1) moved to a different queue,
|
|
* (2) reallocated to a different object,
|
|
* (3) reallocated to a different offset, or
|
|
* (4) cleaned.
|
|
*/
|
|
if (!vm_page_in_laundry(m) || m->object != object ||
|
|
m->pindex != pindex || m->dirty == 0) {
|
|
error = ENXIO;
|
|
goto unlock_all;
|
|
}
|
|
|
|
/*
|
|
* The page may have been busied while the object lock was
|
|
* released.
|
|
*/
|
|
if (vm_page_tryxbusy(m) == 0) {
|
|
error = EBUSY;
|
|
goto unlock_all;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Remove all writeable mappings, failing if the page is wired.
|
|
*/
|
|
if (!vm_page_try_remove_write(m)) {
|
|
vm_page_xunbusy(m);
|
|
error = EBUSY;
|
|
goto unlock_all;
|
|
}
|
|
|
|
/*
|
|
* If a page is dirty, then it is either being washed
|
|
* (but not yet cleaned) or it is still in the
|
|
* laundry. If it is still in the laundry, then we
|
|
* start the cleaning operation.
|
|
*/
|
|
if ((*numpagedout = vm_pageout_cluster(m)) == 0)
|
|
error = EIO;
|
|
|
|
unlock_all:
|
|
VM_OBJECT_WUNLOCK(object);
|
|
|
|
unlock_mp:
|
|
if (mp != NULL) {
|
|
if (vp != NULL)
|
|
vput(vp);
|
|
vm_object_deallocate(object);
|
|
vn_finished_write(mp);
|
|
}
|
|
|
|
return (error);
|
|
}
|
|
|
|
/*
|
|
* Attempt to launder the specified number of pages.
|
|
*
|
|
* Returns the number of pages successfully laundered.
|
|
*/
|
|
static int
|
|
vm_pageout_launder(struct vm_domain *vmd, int launder, bool in_shortfall)
|
|
{
|
|
struct scan_state ss;
|
|
struct vm_pagequeue *pq;
|
|
vm_object_t object;
|
|
vm_page_t m, marker;
|
|
vm_page_astate_t new, old;
|
|
int act_delta, error, numpagedout, queue, refs, starting_target;
|
|
int vnodes_skipped;
|
|
bool pageout_ok;
|
|
|
|
object = NULL;
|
|
starting_target = launder;
|
|
vnodes_skipped = 0;
|
|
|
|
/*
|
|
* Scan the laundry queues for pages eligible to be laundered. We stop
|
|
* once the target number of dirty pages have been laundered, or once
|
|
* we've reached the end of the queue. A single iteration of this loop
|
|
* may cause more than one page to be laundered because of clustering.
|
|
*
|
|
* As an optimization, we avoid laundering from PQ_UNSWAPPABLE when no
|
|
* swap devices are configured.
|
|
*/
|
|
if (atomic_load_acq_int(&swapdev_enabled))
|
|
queue = PQ_UNSWAPPABLE;
|
|
else
|
|
queue = PQ_LAUNDRY;
|
|
|
|
scan:
|
|
marker = &vmd->vmd_markers[queue];
|
|
pq = &vmd->vmd_pagequeues[queue];
|
|
vm_pagequeue_lock(pq);
|
|
vm_pageout_init_scan(&ss, pq, marker, NULL, pq->pq_cnt);
|
|
while (launder > 0 && (m = vm_pageout_next(&ss, false)) != NULL) {
|
|
if (__predict_false((m->flags & PG_MARKER) != 0))
|
|
continue;
|
|
|
|
/*
|
|
* Don't touch a page that was removed from the queue after the
|
|
* page queue lock was released. Otherwise, ensure that any
|
|
* pending queue operations, such as dequeues for wired pages,
|
|
* are handled.
|
|
*/
|
|
if (vm_pageout_defer(m, queue, true))
|
|
continue;
|
|
|
|
/*
|
|
* Lock the page's object.
|
|
*/
|
|
if (object == NULL || object != m->object) {
|
|
if (object != NULL)
|
|
VM_OBJECT_WUNLOCK(object);
|
|
object = atomic_load_ptr(&m->object);
|
|
if (__predict_false(object == NULL))
|
|
/* The page is being freed by another thread. */
|
|
continue;
|
|
|
|
/* Depends on type-stability. */
|
|
VM_OBJECT_WLOCK(object);
|
|
if (__predict_false(m->object != object)) {
|
|
VM_OBJECT_WUNLOCK(object);
|
|
object = NULL;
|
|
continue;
|
|
}
|
|
}
|
|
|
|
if (vm_page_tryxbusy(m) == 0)
|
|
continue;
|
|
|
|
/*
|
|
* Check for wirings now that we hold the object lock and have
|
|
* exclusively busied the page. If the page is mapped, it may
|
|
* still be wired by pmap lookups. The call to
|
|
* vm_page_try_remove_all() below atomically checks for such
|
|
* wirings and removes mappings. If the page is unmapped, the
|
|
* wire count is guaranteed not to increase after this check.
|
|
*/
|
|
if (__predict_false(vm_page_wired(m)))
|
|
goto skip_page;
|
|
|
|
/*
|
|
* Invalid pages can be easily freed. They cannot be
|
|
* mapped; vm_page_free() asserts this.
|
|
*/
|
|
if (vm_page_none_valid(m))
|
|
goto free_page;
|
|
|
|
refs = object->ref_count != 0 ? pmap_ts_referenced(m) : 0;
|
|
|
|
for (old = vm_page_astate_load(m);;) {
|
|
/*
|
|
* Check to see if the page has been removed from the
|
|
* queue since the first such check. Leave it alone if
|
|
* so, discarding any references collected by
|
|
* pmap_ts_referenced().
|
|
*/
|
|
if (__predict_false(_vm_page_queue(old) == PQ_NONE))
|
|
goto skip_page;
|
|
|
|
new = old;
|
|
act_delta = refs;
|
|
if ((old.flags & PGA_REFERENCED) != 0) {
|
|
new.flags &= ~PGA_REFERENCED;
|
|
act_delta++;
|
|
}
|
|
if (act_delta == 0) {
|
|
;
|
|
} else if (object->ref_count != 0) {
|
|
/*
|
|
* Increase the activation count if the page was
|
|
* referenced while in the laundry queue. This
|
|
* makes it less likely that the page will be
|
|
* returned prematurely to the laundry queue.
|
|
*/
|
|
new.act_count += ACT_ADVANCE +
|
|
act_delta;
|
|
if (new.act_count > ACT_MAX)
|
|
new.act_count = ACT_MAX;
|
|
|
|
new.flags &= ~PGA_QUEUE_OP_MASK;
|
|
new.flags |= PGA_REQUEUE;
|
|
new.queue = PQ_ACTIVE;
|
|
if (!vm_page_pqstate_commit(m, &old, new))
|
|
continue;
|
|
|
|
/*
|
|
* If this was a background laundering, count
|
|
* activated pages towards our target. The
|
|
* purpose of background laundering is to ensure
|
|
* that pages are eventually cycled through the
|
|
* laundry queue, and an activation is a valid
|
|
* way out.
|
|
*/
|
|
if (!in_shortfall)
|
|
launder--;
|
|
VM_CNT_INC(v_reactivated);
|
|
goto skip_page;
|
|
} else if ((object->flags & OBJ_DEAD) == 0) {
|
|
new.flags |= PGA_REQUEUE;
|
|
if (!vm_page_pqstate_commit(m, &old, new))
|
|
continue;
|
|
goto skip_page;
|
|
}
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* If the page appears to be clean at the machine-independent
|
|
* layer, then remove all of its mappings from the pmap in
|
|
* anticipation of freeing it. If, however, any of the page's
|
|
* mappings allow write access, then the page may still be
|
|
* modified until the last of those mappings are removed.
|
|
*/
|
|
if (object->ref_count != 0) {
|
|
vm_page_test_dirty(m);
|
|
if (m->dirty == 0 && !vm_page_try_remove_all(m))
|
|
goto skip_page;
|
|
}
|
|
|
|
/*
|
|
* Clean pages are freed, and dirty pages are paged out unless
|
|
* they belong to a dead object. Requeueing dirty pages from
|
|
* dead objects is pointless, as they are being paged out and
|
|
* freed by the thread that destroyed the object.
|
|
*/
|
|
if (m->dirty == 0) {
|
|
free_page:
|
|
/*
|
|
* Now we are guaranteed that no other threads are
|
|
* manipulating the page, check for a last-second
|
|
* reference.
|
|
*/
|
|
if (vm_pageout_defer(m, queue, true))
|
|
goto skip_page;
|
|
vm_page_free(m);
|
|
VM_CNT_INC(v_dfree);
|
|
} else if ((object->flags & OBJ_DEAD) == 0) {
|
|
if ((object->flags & OBJ_SWAP) != 0)
|
|
pageout_ok = disable_swap_pageouts == 0;
|
|
else
|
|
pageout_ok = true;
|
|
if (!pageout_ok) {
|
|
vm_page_launder(m);
|
|
goto skip_page;
|
|
}
|
|
|
|
/*
|
|
* Form a cluster with adjacent, dirty pages from the
|
|
* same object, and page out that entire cluster.
|
|
*
|
|
* The adjacent, dirty pages must also be in the
|
|
* laundry. However, their mappings are not checked
|
|
* for new references. Consequently, a recently
|
|
* referenced page may be paged out. However, that
|
|
* page will not be prematurely reclaimed. After page
|
|
* out, the page will be placed in the inactive queue,
|
|
* where any new references will be detected and the
|
|
* page reactivated.
|
|
*/
|
|
error = vm_pageout_clean(m, &numpagedout);
|
|
if (error == 0) {
|
|
launder -= numpagedout;
|
|
ss.scanned += numpagedout;
|
|
} else if (error == EDEADLK) {
|
|
pageout_lock_miss++;
|
|
vnodes_skipped++;
|
|
}
|
|
object = NULL;
|
|
} else {
|
|
skip_page:
|
|
vm_page_xunbusy(m);
|
|
}
|
|
}
|
|
if (object != NULL) {
|
|
VM_OBJECT_WUNLOCK(object);
|
|
object = NULL;
|
|
}
|
|
vm_pagequeue_lock(pq);
|
|
vm_pageout_end_scan(&ss);
|
|
vm_pagequeue_unlock(pq);
|
|
|
|
if (launder > 0 && queue == PQ_UNSWAPPABLE) {
|
|
queue = PQ_LAUNDRY;
|
|
goto scan;
|
|
}
|
|
|
|
/*
|
|
* Wakeup the sync daemon if we skipped a vnode in a writeable object
|
|
* and we didn't launder enough pages.
|
|
*/
|
|
if (vnodes_skipped > 0 && launder > 0)
|
|
(void)speedup_syncer();
|
|
|
|
return (starting_target - launder);
|
|
}
|
|
|
|
/*
|
|
* Compute the integer square root.
|
|
*/
|
|
static u_int
|
|
isqrt(u_int num)
|
|
{
|
|
u_int bit, root, tmp;
|
|
|
|
bit = num != 0 ? (1u << ((fls(num) - 1) & ~1)) : 0;
|
|
root = 0;
|
|
while (bit != 0) {
|
|
tmp = root + bit;
|
|
root >>= 1;
|
|
if (num >= tmp) {
|
|
num -= tmp;
|
|
root += bit;
|
|
}
|
|
bit >>= 2;
|
|
}
|
|
return (root);
|
|
}
|
|
|
|
/*
|
|
* Perform the work of the laundry thread: periodically wake up and determine
|
|
* whether any pages need to be laundered. If so, determine the number of pages
|
|
* that need to be laundered, and launder them.
|
|
*/
|
|
static void
|
|
vm_pageout_laundry_worker(void *arg)
|
|
{
|
|
struct vm_domain *vmd;
|
|
struct vm_pagequeue *pq;
|
|
uint64_t nclean, ndirty, nfreed;
|
|
int domain, last_target, launder, shortfall, shortfall_cycle, target;
|
|
bool in_shortfall;
|
|
|
|
domain = (uintptr_t)arg;
|
|
vmd = VM_DOMAIN(domain);
|
|
pq = &vmd->vmd_pagequeues[PQ_LAUNDRY];
|
|
KASSERT(vmd->vmd_segs != 0, ("domain without segments"));
|
|
|
|
shortfall = 0;
|
|
in_shortfall = false;
|
|
shortfall_cycle = 0;
|
|
last_target = target = 0;
|
|
nfreed = 0;
|
|
|
|
/*
|
|
* Calls to these handlers are serialized by the swap syscall lock.
|
|
*/
|
|
(void)EVENTHANDLER_REGISTER(swapon, vm_pageout_swapon, vmd,
|
|
EVENTHANDLER_PRI_ANY);
|
|
(void)EVENTHANDLER_REGISTER(swapoff, vm_pageout_swapoff, vmd,
|
|
EVENTHANDLER_PRI_ANY);
|
|
|
|
/*
|
|
* The pageout laundry worker is never done, so loop forever.
|
|
*/
|
|
for (;;) {
|
|
KASSERT(target >= 0, ("negative target %d", target));
|
|
KASSERT(shortfall_cycle >= 0,
|
|
("negative cycle %d", shortfall_cycle));
|
|
launder = 0;
|
|
|
|
/*
|
|
* First determine whether we need to launder pages to meet a
|
|
* shortage of free pages.
|
|
*/
|
|
if (shortfall > 0) {
|
|
in_shortfall = true;
|
|
shortfall_cycle = VM_LAUNDER_RATE / VM_INACT_SCAN_RATE;
|
|
target = shortfall;
|
|
} else if (!in_shortfall)
|
|
goto trybackground;
|
|
else if (shortfall_cycle == 0 || vm_laundry_target(vmd) <= 0) {
|
|
/*
|
|
* We recently entered shortfall and began laundering
|
|
* pages. If we have completed that laundering run
|
|
* (and we are no longer in shortfall) or we have met
|
|
* our laundry target through other activity, then we
|
|
* can stop laundering pages.
|
|
*/
|
|
in_shortfall = false;
|
|
target = 0;
|
|
goto trybackground;
|
|
}
|
|
launder = target / shortfall_cycle--;
|
|
goto dolaundry;
|
|
|
|
/*
|
|
* There's no immediate need to launder any pages; see if we
|
|
* meet the conditions to perform background laundering:
|
|
*
|
|
* 1. The ratio of dirty to clean inactive pages exceeds the
|
|
* background laundering threshold, or
|
|
* 2. we haven't yet reached the target of the current
|
|
* background laundering run.
|
|
*
|
|
* The background laundering threshold is not a constant.
|
|
* Instead, it is a slowly growing function of the number of
|
|
* clean pages freed by the page daemon since the last
|
|
* background laundering. Thus, as the ratio of dirty to
|
|
* clean inactive pages grows, the amount of memory pressure
|
|
* required to trigger laundering decreases. We ensure
|
|
* that the threshold is non-zero after an inactive queue
|
|
* scan, even if that scan failed to free a single clean page.
|
|
*/
|
|
trybackground:
|
|
nclean = vmd->vmd_free_count +
|
|
vmd->vmd_pagequeues[PQ_INACTIVE].pq_cnt;
|
|
ndirty = vmd->vmd_pagequeues[PQ_LAUNDRY].pq_cnt;
|
|
if (target == 0 && ndirty * isqrt(howmany(nfreed + 1,
|
|
vmd->vmd_free_target - vmd->vmd_free_min)) >= nclean) {
|
|
target = vmd->vmd_background_launder_target;
|
|
}
|
|
|
|
/*
|
|
* We have a non-zero background laundering target. If we've
|
|
* laundered up to our maximum without observing a page daemon
|
|
* request, just stop. This is a safety belt that ensures we
|
|
* don't launder an excessive amount if memory pressure is low
|
|
* and the ratio of dirty to clean pages is large. Otherwise,
|
|
* proceed at the background laundering rate.
|
|
*/
|
|
if (target > 0) {
|
|
if (nfreed > 0) {
|
|
nfreed = 0;
|
|
last_target = target;
|
|
} else if (last_target - target >=
|
|
vm_background_launder_max * PAGE_SIZE / 1024) {
|
|
target = 0;
|
|
}
|
|
launder = vm_background_launder_rate * PAGE_SIZE / 1024;
|
|
launder /= VM_LAUNDER_RATE;
|
|
if (launder > target)
|
|
launder = target;
|
|
}
|
|
|
|
dolaundry:
|
|
if (launder > 0) {
|
|
/*
|
|
* Because of I/O clustering, the number of laundered
|
|
* pages could exceed "target" by the maximum size of
|
|
* a cluster minus one.
|
|
*/
|
|
target -= min(vm_pageout_launder(vmd, launder,
|
|
in_shortfall), target);
|
|
pause("laundp", hz / VM_LAUNDER_RATE);
|
|
}
|
|
|
|
/*
|
|
* If we're not currently laundering pages and the page daemon
|
|
* hasn't posted a new request, sleep until the page daemon
|
|
* kicks us.
|
|
*/
|
|
vm_pagequeue_lock(pq);
|
|
if (target == 0 && vmd->vmd_laundry_request == VM_LAUNDRY_IDLE)
|
|
(void)mtx_sleep(&vmd->vmd_laundry_request,
|
|
vm_pagequeue_lockptr(pq), PVM, "launds", 0);
|
|
|
|
/*
|
|
* If the pagedaemon has indicated that it's in shortfall, start
|
|
* a shortfall laundering unless we're already in the middle of
|
|
* one. This may preempt a background laundering.
|
|
*/
|
|
if (vmd->vmd_laundry_request == VM_LAUNDRY_SHORTFALL &&
|
|
(!in_shortfall || shortfall_cycle == 0)) {
|
|
shortfall = vm_laundry_target(vmd) +
|
|
vmd->vmd_pageout_deficit;
|
|
target = 0;
|
|
} else
|
|
shortfall = 0;
|
|
|
|
if (target == 0)
|
|
vmd->vmd_laundry_request = VM_LAUNDRY_IDLE;
|
|
nfreed += vmd->vmd_clean_pages_freed;
|
|
vmd->vmd_clean_pages_freed = 0;
|
|
vm_pagequeue_unlock(pq);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Compute the number of pages we want to try to move from the
|
|
* active queue to either the inactive or laundry queue.
|
|
*
|
|
* When scanning active pages during a shortage, we make clean pages
|
|
* count more heavily towards the page shortage than dirty pages.
|
|
* This is because dirty pages must be laundered before they can be
|
|
* reused and thus have less utility when attempting to quickly
|
|
* alleviate a free page shortage. However, this weighting also
|
|
* causes the scan to deactivate dirty pages more aggressively,
|
|
* improving the effectiveness of clustering.
|
|
*/
|
|
static int
|
|
vm_pageout_active_target(struct vm_domain *vmd)
|
|
{
|
|
int shortage;
|
|
|
|
shortage = vmd->vmd_inactive_target + vm_paging_target(vmd) -
|
|
(vmd->vmd_pagequeues[PQ_INACTIVE].pq_cnt +
|
|
vmd->vmd_pagequeues[PQ_LAUNDRY].pq_cnt / act_scan_laundry_weight);
|
|
shortage *= act_scan_laundry_weight;
|
|
return (shortage);
|
|
}
|
|
|
|
/*
|
|
* Scan the active queue. If there is no shortage of inactive pages, scan a
|
|
* small portion of the queue in order to maintain quasi-LRU.
|
|
*/
|
|
static void
|
|
vm_pageout_scan_active(struct vm_domain *vmd, int page_shortage)
|
|
{
|
|
struct scan_state ss;
|
|
vm_object_t object;
|
|
vm_page_t m, marker;
|
|
struct vm_pagequeue *pq;
|
|
vm_page_astate_t old, new;
|
|
long min_scan;
|
|
int act_delta, max_scan, ps_delta, refs, scan_tick;
|
|
uint8_t nqueue;
|
|
|
|
marker = &vmd->vmd_markers[PQ_ACTIVE];
|
|
pq = &vmd->vmd_pagequeues[PQ_ACTIVE];
|
|
vm_pagequeue_lock(pq);
|
|
|
|
/*
|
|
* If we're just idle polling attempt to visit every
|
|
* active page within 'update_period' seconds.
|
|
*/
|
|
scan_tick = ticks;
|
|
if (vm_pageout_update_period != 0) {
|
|
min_scan = pq->pq_cnt;
|
|
min_scan *= scan_tick - vmd->vmd_last_active_scan;
|
|
min_scan /= hz * vm_pageout_update_period;
|
|
} else
|
|
min_scan = 0;
|
|
if (min_scan > 0 || (page_shortage > 0 && pq->pq_cnt > 0))
|
|
vmd->vmd_last_active_scan = scan_tick;
|
|
|
|
/*
|
|
* Scan the active queue for pages that can be deactivated. Update
|
|
* the per-page activity counter and use it to identify deactivation
|
|
* candidates. Held pages may be deactivated.
|
|
*
|
|
* To avoid requeuing each page that remains in the active queue, we
|
|
* implement the CLOCK algorithm. To keep the implementation of the
|
|
* enqueue operation consistent for all page queues, we use two hands,
|
|
* represented by marker pages. Scans begin at the first hand, which
|
|
* precedes the second hand in the queue. When the two hands meet,
|
|
* they are moved back to the head and tail of the queue, respectively,
|
|
* and scanning resumes.
|
|
*/
|
|
max_scan = page_shortage > 0 ? pq->pq_cnt : min_scan;
|
|
act_scan:
|
|
vm_pageout_init_scan(&ss, pq, marker, &vmd->vmd_clock[0], max_scan);
|
|
while ((m = vm_pageout_next(&ss, false)) != NULL) {
|
|
if (__predict_false(m == &vmd->vmd_clock[1])) {
|
|
vm_pagequeue_lock(pq);
|
|
TAILQ_REMOVE(&pq->pq_pl, &vmd->vmd_clock[0], plinks.q);
|
|
TAILQ_REMOVE(&pq->pq_pl, &vmd->vmd_clock[1], plinks.q);
|
|
TAILQ_INSERT_HEAD(&pq->pq_pl, &vmd->vmd_clock[0],
|
|
plinks.q);
|
|
TAILQ_INSERT_TAIL(&pq->pq_pl, &vmd->vmd_clock[1],
|
|
plinks.q);
|
|
max_scan -= ss.scanned;
|
|
vm_pageout_end_scan(&ss);
|
|
goto act_scan;
|
|
}
|
|
if (__predict_false((m->flags & PG_MARKER) != 0))
|
|
continue;
|
|
|
|
/*
|
|
* Don't touch a page that was removed from the queue after the
|
|
* page queue lock was released. Otherwise, ensure that any
|
|
* pending queue operations, such as dequeues for wired pages,
|
|
* are handled.
|
|
*/
|
|
if (vm_pageout_defer(m, PQ_ACTIVE, true))
|
|
continue;
|
|
|
|
/*
|
|
* A page's object pointer may be set to NULL before
|
|
* the object lock is acquired.
|
|
*/
|
|
object = atomic_load_ptr(&m->object);
|
|
if (__predict_false(object == NULL))
|
|
/*
|
|
* The page has been removed from its object.
|
|
*/
|
|
continue;
|
|
|
|
/* Deferred free of swap space. */
|
|
if ((m->a.flags & PGA_SWAP_FREE) != 0 &&
|
|
VM_OBJECT_TRYWLOCK(object)) {
|
|
if (m->object == object)
|
|
vm_pager_page_unswapped(m);
|
|
VM_OBJECT_WUNLOCK(object);
|
|
}
|
|
|
|
/*
|
|
* Check to see "how much" the page has been used.
|
|
*
|
|
* Test PGA_REFERENCED after calling pmap_ts_referenced() so
|
|
* that a reference from a concurrently destroyed mapping is
|
|
* observed here and now.
|
|
*
|
|
* Perform an unsynchronized object ref count check. While
|
|
* the page lock ensures that the page is not reallocated to
|
|
* another object, in particular, one with unmanaged mappings
|
|
* that cannot support pmap_ts_referenced(), two races are,
|
|
* nonetheless, possible:
|
|
* 1) The count was transitioning to zero, but we saw a non-
|
|
* zero value. pmap_ts_referenced() will return zero
|
|
* because the page is not mapped.
|
|
* 2) The count was transitioning to one, but we saw zero.
|
|
* This race delays the detection of a new reference. At
|
|
* worst, we will deactivate and reactivate the page.
|
|
*/
|
|
refs = object->ref_count != 0 ? pmap_ts_referenced(m) : 0;
|
|
|
|
old = vm_page_astate_load(m);
|
|
do {
|
|
/*
|
|
* Check to see if the page has been removed from the
|
|
* queue since the first such check. Leave it alone if
|
|
* so, discarding any references collected by
|
|
* pmap_ts_referenced().
|
|
*/
|
|
if (__predict_false(_vm_page_queue(old) == PQ_NONE)) {
|
|
ps_delta = 0;
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* Advance or decay the act_count based on recent usage.
|
|
*/
|
|
new = old;
|
|
act_delta = refs;
|
|
if ((old.flags & PGA_REFERENCED) != 0) {
|
|
new.flags &= ~PGA_REFERENCED;
|
|
act_delta++;
|
|
}
|
|
if (act_delta != 0) {
|
|
new.act_count += ACT_ADVANCE + act_delta;
|
|
if (new.act_count > ACT_MAX)
|
|
new.act_count = ACT_MAX;
|
|
} else {
|
|
new.act_count -= min(new.act_count,
|
|
ACT_DECLINE);
|
|
}
|
|
|
|
if (new.act_count > 0) {
|
|
/*
|
|
* Adjust the activation count and keep the page
|
|
* in the active queue. The count might be left
|
|
* unchanged if it is saturated. The page may
|
|
* have been moved to a different queue since we
|
|
* started the scan, in which case we move it
|
|
* back.
|
|
*/
|
|
ps_delta = 0;
|
|
if (old.queue != PQ_ACTIVE) {
|
|
new.flags &= ~PGA_QUEUE_OP_MASK;
|
|
new.flags |= PGA_REQUEUE;
|
|
new.queue = PQ_ACTIVE;
|
|
}
|
|
} else {
|
|
/*
|
|
* When not short for inactive pages, let dirty
|
|
* pages go through the inactive queue before
|
|
* moving to the laundry queue. This gives them
|
|
* some extra time to be reactivated,
|
|
* potentially avoiding an expensive pageout.
|
|
* However, during a page shortage, the inactive
|
|
* queue is necessarily small, and so dirty
|
|
* pages would only spend a trivial amount of
|
|
* time in the inactive queue. Therefore, we
|
|
* might as well place them directly in the
|
|
* laundry queue to reduce queuing overhead.
|
|
*
|
|
* Calling vm_page_test_dirty() here would
|
|
* require acquisition of the object's write
|
|
* lock. However, during a page shortage,
|
|
* directing dirty pages into the laundry queue
|
|
* is only an optimization and not a
|
|
* requirement. Therefore, we simply rely on
|
|
* the opportunistic updates to the page's dirty
|
|
* field by the pmap.
|
|
*/
|
|
if (page_shortage <= 0) {
|
|
nqueue = PQ_INACTIVE;
|
|
ps_delta = 0;
|
|
} else if (m->dirty == 0) {
|
|
nqueue = PQ_INACTIVE;
|
|
ps_delta = act_scan_laundry_weight;
|
|
} else {
|
|
nqueue = PQ_LAUNDRY;
|
|
ps_delta = 1;
|
|
}
|
|
|
|
new.flags &= ~PGA_QUEUE_OP_MASK;
|
|
new.flags |= PGA_REQUEUE;
|
|
new.queue = nqueue;
|
|
}
|
|
} while (!vm_page_pqstate_commit(m, &old, new));
|
|
|
|
page_shortage -= ps_delta;
|
|
}
|
|
vm_pagequeue_lock(pq);
|
|
TAILQ_REMOVE(&pq->pq_pl, &vmd->vmd_clock[0], plinks.q);
|
|
TAILQ_INSERT_AFTER(&pq->pq_pl, marker, &vmd->vmd_clock[0], plinks.q);
|
|
vm_pageout_end_scan(&ss);
|
|
vm_pagequeue_unlock(pq);
|
|
}
|
|
|
|
static int
|
|
vm_pageout_reinsert_inactive_page(struct vm_pagequeue *pq, vm_page_t marker,
|
|
vm_page_t m)
|
|
{
|
|
vm_page_astate_t as;
|
|
|
|
vm_pagequeue_assert_locked(pq);
|
|
|
|
as = vm_page_astate_load(m);
|
|
if (as.queue != PQ_INACTIVE || (as.flags & PGA_ENQUEUED) != 0)
|
|
return (0);
|
|
vm_page_aflag_set(m, PGA_ENQUEUED);
|
|
TAILQ_INSERT_BEFORE(marker, m, plinks.q);
|
|
return (1);
|
|
}
|
|
|
|
/*
|
|
* Re-add stuck pages to the inactive queue. We will examine them again
|
|
* during the next scan. If the queue state of a page has changed since
|
|
* it was physically removed from the page queue in
|
|
* vm_pageout_collect_batch(), don't do anything with that page.
|
|
*/
|
|
static void
|
|
vm_pageout_reinsert_inactive(struct scan_state *ss, struct vm_batchqueue *bq,
|
|
vm_page_t m)
|
|
{
|
|
struct vm_pagequeue *pq;
|
|
vm_page_t marker;
|
|
int delta;
|
|
|
|
delta = 0;
|
|
marker = ss->marker;
|
|
pq = ss->pq;
|
|
|
|
if (m != NULL) {
|
|
if (vm_batchqueue_insert(bq, m))
|
|
return;
|
|
vm_pagequeue_lock(pq);
|
|
delta += vm_pageout_reinsert_inactive_page(pq, marker, m);
|
|
} else
|
|
vm_pagequeue_lock(pq);
|
|
while ((m = vm_batchqueue_pop(bq)) != NULL)
|
|
delta += vm_pageout_reinsert_inactive_page(pq, marker, m);
|
|
vm_pagequeue_cnt_add(pq, delta);
|
|
vm_pagequeue_unlock(pq);
|
|
vm_batchqueue_init(bq);
|
|
}
|
|
|
|
static void
|
|
vm_pageout_scan_inactive(struct vm_domain *vmd, int page_shortage)
|
|
{
|
|
struct timeval start, end;
|
|
struct scan_state ss;
|
|
struct vm_batchqueue rq;
|
|
struct vm_page marker_page;
|
|
vm_page_t m, marker;
|
|
struct vm_pagequeue *pq;
|
|
vm_object_t object;
|
|
vm_page_astate_t old, new;
|
|
int act_delta, addl_page_shortage, starting_page_shortage, refs;
|
|
|
|
object = NULL;
|
|
vm_batchqueue_init(&rq);
|
|
getmicrouptime(&start);
|
|
|
|
/*
|
|
* The addl_page_shortage is an estimate of the number of temporarily
|
|
* stuck pages in the inactive queue. In other words, the
|
|
* number of pages from the inactive count that should be
|
|
* discounted in setting the target for the active queue scan.
|
|
*/
|
|
addl_page_shortage = 0;
|
|
|
|
/*
|
|
* Start scanning the inactive queue for pages that we can free. The
|
|
* scan will stop when we reach the target or we have scanned the
|
|
* entire queue. (Note that m->a.act_count is not used to make
|
|
* decisions for the inactive queue, only for the active queue.)
|
|
*/
|
|
starting_page_shortage = page_shortage;
|
|
marker = &marker_page;
|
|
vm_page_init_marker(marker, PQ_INACTIVE, 0);
|
|
pq = &vmd->vmd_pagequeues[PQ_INACTIVE];
|
|
vm_pagequeue_lock(pq);
|
|
vm_pageout_init_scan(&ss, pq, marker, NULL, pq->pq_cnt);
|
|
while (page_shortage > 0 && (m = vm_pageout_next(&ss, true)) != NULL) {
|
|
KASSERT((m->flags & PG_MARKER) == 0,
|
|
("marker page %p was dequeued", m));
|
|
|
|
/*
|
|
* Don't touch a page that was removed from the queue after the
|
|
* page queue lock was released. Otherwise, ensure that any
|
|
* pending queue operations, such as dequeues for wired pages,
|
|
* are handled.
|
|
*/
|
|
if (vm_pageout_defer(m, PQ_INACTIVE, false))
|
|
continue;
|
|
|
|
/*
|
|
* Lock the page's object.
|
|
*/
|
|
if (object == NULL || object != m->object) {
|
|
if (object != NULL)
|
|
VM_OBJECT_WUNLOCK(object);
|
|
object = atomic_load_ptr(&m->object);
|
|
if (__predict_false(object == NULL))
|
|
/* The page is being freed by another thread. */
|
|
continue;
|
|
|
|
/* Depends on type-stability. */
|
|
VM_OBJECT_WLOCK(object);
|
|
if (__predict_false(m->object != object)) {
|
|
VM_OBJECT_WUNLOCK(object);
|
|
object = NULL;
|
|
goto reinsert;
|
|
}
|
|
}
|
|
|
|
if (vm_page_tryxbusy(m) == 0) {
|
|
/*
|
|
* Don't mess with busy pages. Leave them at
|
|
* the front of the queue. Most likely, they
|
|
* are being paged out and will leave the
|
|
* queue shortly after the scan finishes. So,
|
|
* they ought to be discounted from the
|
|
* inactive count.
|
|
*/
|
|
addl_page_shortage++;
|
|
goto reinsert;
|
|
}
|
|
|
|
/* Deferred free of swap space. */
|
|
if ((m->a.flags & PGA_SWAP_FREE) != 0)
|
|
vm_pager_page_unswapped(m);
|
|
|
|
/*
|
|
* Check for wirings now that we hold the object lock and have
|
|
* exclusively busied the page. If the page is mapped, it may
|
|
* still be wired by pmap lookups. The call to
|
|
* vm_page_try_remove_all() below atomically checks for such
|
|
* wirings and removes mappings. If the page is unmapped, the
|
|
* wire count is guaranteed not to increase after this check.
|
|
*/
|
|
if (__predict_false(vm_page_wired(m)))
|
|
goto skip_page;
|
|
|
|
/*
|
|
* Invalid pages can be easily freed. They cannot be
|
|
* mapped, vm_page_free() asserts this.
|
|
*/
|
|
if (vm_page_none_valid(m))
|
|
goto free_page;
|
|
|
|
refs = object->ref_count != 0 ? pmap_ts_referenced(m) : 0;
|
|
|
|
for (old = vm_page_astate_load(m);;) {
|
|
/*
|
|
* Check to see if the page has been removed from the
|
|
* queue since the first such check. Leave it alone if
|
|
* so, discarding any references collected by
|
|
* pmap_ts_referenced().
|
|
*/
|
|
if (__predict_false(_vm_page_queue(old) == PQ_NONE))
|
|
goto skip_page;
|
|
|
|
new = old;
|
|
act_delta = refs;
|
|
if ((old.flags & PGA_REFERENCED) != 0) {
|
|
new.flags &= ~PGA_REFERENCED;
|
|
act_delta++;
|
|
}
|
|
if (act_delta == 0) {
|
|
;
|
|
} else if (object->ref_count != 0) {
|
|
/*
|
|
* Increase the activation count if the
|
|
* page was referenced while in the
|
|
* inactive queue. This makes it less
|
|
* likely that the page will be returned
|
|
* prematurely to the inactive queue.
|
|
*/
|
|
new.act_count += ACT_ADVANCE +
|
|
act_delta;
|
|
if (new.act_count > ACT_MAX)
|
|
new.act_count = ACT_MAX;
|
|
|
|
new.flags &= ~PGA_QUEUE_OP_MASK;
|
|
new.flags |= PGA_REQUEUE;
|
|
new.queue = PQ_ACTIVE;
|
|
if (!vm_page_pqstate_commit(m, &old, new))
|
|
continue;
|
|
|
|
VM_CNT_INC(v_reactivated);
|
|
goto skip_page;
|
|
} else if ((object->flags & OBJ_DEAD) == 0) {
|
|
new.queue = PQ_INACTIVE;
|
|
new.flags |= PGA_REQUEUE;
|
|
if (!vm_page_pqstate_commit(m, &old, new))
|
|
continue;
|
|
goto skip_page;
|
|
}
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* If the page appears to be clean at the machine-independent
|
|
* layer, then remove all of its mappings from the pmap in
|
|
* anticipation of freeing it. If, however, any of the page's
|
|
* mappings allow write access, then the page may still be
|
|
* modified until the last of those mappings are removed.
|
|
*/
|
|
if (object->ref_count != 0) {
|
|
vm_page_test_dirty(m);
|
|
if (m->dirty == 0 && !vm_page_try_remove_all(m))
|
|
goto skip_page;
|
|
}
|
|
|
|
/*
|
|
* Clean pages can be freed, but dirty pages must be sent back
|
|
* to the laundry, unless they belong to a dead object.
|
|
* Requeueing dirty pages from dead objects is pointless, as
|
|
* they are being paged out and freed by the thread that
|
|
* destroyed the object.
|
|
*/
|
|
if (m->dirty == 0) {
|
|
free_page:
|
|
/*
|
|
* Now we are guaranteed that no other threads are
|
|
* manipulating the page, check for a last-second
|
|
* reference that would save it from doom.
|
|
*/
|
|
if (vm_pageout_defer(m, PQ_INACTIVE, false))
|
|
goto skip_page;
|
|
|
|
/*
|
|
* Because we dequeued the page and have already checked
|
|
* for pending dequeue and enqueue requests, we can
|
|
* safely disassociate the page from the inactive queue
|
|
* without holding the queue lock.
|
|
*/
|
|
m->a.queue = PQ_NONE;
|
|
vm_page_free(m);
|
|
page_shortage--;
|
|
continue;
|
|
}
|
|
if ((object->flags & OBJ_DEAD) == 0)
|
|
vm_page_launder(m);
|
|
skip_page:
|
|
vm_page_xunbusy(m);
|
|
continue;
|
|
reinsert:
|
|
vm_pageout_reinsert_inactive(&ss, &rq, m);
|
|
}
|
|
if (object != NULL)
|
|
VM_OBJECT_WUNLOCK(object);
|
|
vm_pageout_reinsert_inactive(&ss, &rq, NULL);
|
|
vm_pageout_reinsert_inactive(&ss, &ss.bq, NULL);
|
|
vm_pagequeue_lock(pq);
|
|
vm_pageout_end_scan(&ss);
|
|
vm_pagequeue_unlock(pq);
|
|
|
|
/*
|
|
* Record the remaining shortage and the progress and rate it was made.
|
|
*/
|
|
atomic_add_int(&vmd->vmd_addl_shortage, addl_page_shortage);
|
|
getmicrouptime(&end);
|
|
timevalsub(&end, &start);
|
|
atomic_add_int(&vmd->vmd_inactive_us,
|
|
end.tv_sec * 1000000 + end.tv_usec);
|
|
atomic_add_int(&vmd->vmd_inactive_freed,
|
|
starting_page_shortage - page_shortage);
|
|
}
|
|
|
|
/*
|
|
* Dispatch a number of inactive threads according to load and collect the
|
|
* results to present a coherent view of paging activity on this domain.
|
|
*/
|
|
static int
|
|
vm_pageout_inactive_dispatch(struct vm_domain *vmd, int shortage)
|
|
{
|
|
u_int freed, pps, slop, threads, us;
|
|
|
|
vmd->vmd_inactive_shortage = shortage;
|
|
slop = 0;
|
|
|
|
/*
|
|
* If we have more work than we can do in a quarter of our interval, we
|
|
* fire off multiple threads to process it.
|
|
*/
|
|
threads = vmd->vmd_inactive_threads;
|
|
if (threads > 1 && vmd->vmd_inactive_pps != 0 &&
|
|
shortage > vmd->vmd_inactive_pps / VM_INACT_SCAN_RATE / 4) {
|
|
vmd->vmd_inactive_shortage /= threads;
|
|
slop = shortage % threads;
|
|
vm_domain_pageout_lock(vmd);
|
|
blockcount_acquire(&vmd->vmd_inactive_starting, threads - 1);
|
|
blockcount_acquire(&vmd->vmd_inactive_running, threads - 1);
|
|
wakeup(&vmd->vmd_inactive_shortage);
|
|
vm_domain_pageout_unlock(vmd);
|
|
}
|
|
|
|
/* Run the local thread scan. */
|
|
vm_pageout_scan_inactive(vmd, vmd->vmd_inactive_shortage + slop);
|
|
|
|
/*
|
|
* Block until helper threads report results and then accumulate
|
|
* totals.
|
|
*/
|
|
blockcount_wait(&vmd->vmd_inactive_running, NULL, "vmpoid", PVM);
|
|
freed = atomic_readandclear_int(&vmd->vmd_inactive_freed);
|
|
VM_CNT_ADD(v_dfree, freed);
|
|
|
|
/*
|
|
* Calculate the per-thread paging rate with an exponential decay of
|
|
* prior results. Careful to avoid integer rounding errors with large
|
|
* us values.
|
|
*/
|
|
us = max(atomic_readandclear_int(&vmd->vmd_inactive_us), 1);
|
|
if (us > 1000000)
|
|
/* Keep rounding to tenths */
|
|
pps = (freed * 10) / ((us * 10) / 1000000);
|
|
else
|
|
pps = (1000000 / us) * freed;
|
|
vmd->vmd_inactive_pps = (vmd->vmd_inactive_pps / 2) + (pps / 2);
|
|
|
|
return (shortage - freed);
|
|
}
|
|
|
|
/*
|
|
* Attempt to reclaim the requested number of pages from the inactive queue.
|
|
* Returns true if the shortage was addressed.
|
|
*/
|
|
static int
|
|
vm_pageout_inactive(struct vm_domain *vmd, int shortage, int *addl_shortage)
|
|
{
|
|
struct vm_pagequeue *pq;
|
|
u_int addl_page_shortage, deficit, page_shortage;
|
|
u_int starting_page_shortage;
|
|
|
|
/*
|
|
* vmd_pageout_deficit counts the number of pages requested in
|
|
* allocations that failed because of a free page shortage. We assume
|
|
* that the allocations will be reattempted and thus include the deficit
|
|
* in our scan target.
|
|
*/
|
|
deficit = atomic_readandclear_int(&vmd->vmd_pageout_deficit);
|
|
starting_page_shortage = shortage + deficit;
|
|
|
|
/*
|
|
* Run the inactive scan on as many threads as is necessary.
|
|
*/
|
|
page_shortage = vm_pageout_inactive_dispatch(vmd, starting_page_shortage);
|
|
addl_page_shortage = atomic_readandclear_int(&vmd->vmd_addl_shortage);
|
|
|
|
/*
|
|
* Wake up the laundry thread so that it can perform any needed
|
|
* laundering. If we didn't meet our target, we're in shortfall and
|
|
* need to launder more aggressively. If PQ_LAUNDRY is empty and no
|
|
* swap devices are configured, the laundry thread has no work to do, so
|
|
* don't bother waking it up.
|
|
*
|
|
* The laundry thread uses the number of inactive queue scans elapsed
|
|
* since the last laundering to determine whether to launder again, so
|
|
* keep count.
|
|
*/
|
|
if (starting_page_shortage > 0) {
|
|
pq = &vmd->vmd_pagequeues[PQ_LAUNDRY];
|
|
vm_pagequeue_lock(pq);
|
|
if (vmd->vmd_laundry_request == VM_LAUNDRY_IDLE &&
|
|
(pq->pq_cnt > 0 || atomic_load_acq_int(&swapdev_enabled))) {
|
|
if (page_shortage > 0) {
|
|
vmd->vmd_laundry_request = VM_LAUNDRY_SHORTFALL;
|
|
VM_CNT_INC(v_pdshortfalls);
|
|
} else if (vmd->vmd_laundry_request !=
|
|
VM_LAUNDRY_SHORTFALL)
|
|
vmd->vmd_laundry_request =
|
|
VM_LAUNDRY_BACKGROUND;
|
|
wakeup(&vmd->vmd_laundry_request);
|
|
}
|
|
vmd->vmd_clean_pages_freed +=
|
|
starting_page_shortage - page_shortage;
|
|
vm_pagequeue_unlock(pq);
|
|
}
|
|
|
|
/*
|
|
* Wakeup the swapout daemon if we didn't free the targeted number of
|
|
* pages.
|
|
*/
|
|
if (page_shortage > 0)
|
|
vm_swapout_run();
|
|
|
|
/*
|
|
* If the inactive queue scan fails repeatedly to meet its
|
|
* target, kill the largest process.
|
|
*/
|
|
vm_pageout_mightbe_oom(vmd, page_shortage, starting_page_shortage);
|
|
|
|
/*
|
|
* Reclaim pages by swapping out idle processes, if configured to do so.
|
|
*/
|
|
vm_swapout_run_idle();
|
|
|
|
/*
|
|
* See the description of addl_page_shortage above.
|
|
*/
|
|
*addl_shortage = addl_page_shortage + deficit;
|
|
|
|
return (page_shortage <= 0);
|
|
}
|
|
|
|
static int vm_pageout_oom_vote;
|
|
|
|
/*
|
|
* The pagedaemon threads randlomly select one to perform the
|
|
* OOM. Trying to kill processes before all pagedaemons
|
|
* failed to reach free target is premature.
|
|
*/
|
|
static void
|
|
vm_pageout_mightbe_oom(struct vm_domain *vmd, int page_shortage,
|
|
int starting_page_shortage)
|
|
{
|
|
int old_vote;
|
|
|
|
if (starting_page_shortage <= 0 || starting_page_shortage !=
|
|
page_shortage)
|
|
vmd->vmd_oom_seq = 0;
|
|
else
|
|
vmd->vmd_oom_seq++;
|
|
if (vmd->vmd_oom_seq < vm_pageout_oom_seq) {
|
|
if (vmd->vmd_oom) {
|
|
vmd->vmd_oom = FALSE;
|
|
atomic_subtract_int(&vm_pageout_oom_vote, 1);
|
|
}
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* Do not follow the call sequence until OOM condition is
|
|
* cleared.
|
|
*/
|
|
vmd->vmd_oom_seq = 0;
|
|
|
|
if (vmd->vmd_oom)
|
|
return;
|
|
|
|
vmd->vmd_oom = TRUE;
|
|
old_vote = atomic_fetchadd_int(&vm_pageout_oom_vote, 1);
|
|
if (old_vote != vm_ndomains - 1)
|
|
return;
|
|
|
|
/*
|
|
* The current pagedaemon thread is the last in the quorum to
|
|
* start OOM. Initiate the selection and signaling of the
|
|
* victim.
|
|
*/
|
|
vm_pageout_oom(VM_OOM_MEM);
|
|
|
|
/*
|
|
* After one round of OOM terror, recall our vote. On the
|
|
* next pass, current pagedaemon would vote again if the low
|
|
* memory condition is still there, due to vmd_oom being
|
|
* false.
|
|
*/
|
|
vmd->vmd_oom = FALSE;
|
|
atomic_subtract_int(&vm_pageout_oom_vote, 1);
|
|
}
|
|
|
|
/*
|
|
* The OOM killer is the page daemon's action of last resort when
|
|
* memory allocation requests have been stalled for a prolonged period
|
|
* of time because it cannot reclaim memory. This function computes
|
|
* the approximate number of physical pages that could be reclaimed if
|
|
* the specified address space is destroyed.
|
|
*
|
|
* Private, anonymous memory owned by the address space is the
|
|
* principal resource that we expect to recover after an OOM kill.
|
|
* Since the physical pages mapped by the address space's COW entries
|
|
* are typically shared pages, they are unlikely to be released and so
|
|
* they are not counted.
|
|
*
|
|
* To get to the point where the page daemon runs the OOM killer, its
|
|
* efforts to write-back vnode-backed pages may have stalled. This
|
|
* could be caused by a memory allocation deadlock in the write path
|
|
* that might be resolved by an OOM kill. Therefore, physical pages
|
|
* belonging to vnode-backed objects are counted, because they might
|
|
* be freed without being written out first if the address space holds
|
|
* the last reference to an unlinked vnode.
|
|
*
|
|
* Similarly, physical pages belonging to OBJT_PHYS objects are
|
|
* counted because the address space might hold the last reference to
|
|
* the object.
|
|
*/
|
|
static long
|
|
vm_pageout_oom_pagecount(struct vmspace *vmspace)
|
|
{
|
|
vm_map_t map;
|
|
vm_map_entry_t entry;
|
|
vm_object_t obj;
|
|
long res;
|
|
|
|
map = &vmspace->vm_map;
|
|
KASSERT(!map->system_map, ("system map"));
|
|
sx_assert(&map->lock, SA_LOCKED);
|
|
res = 0;
|
|
VM_MAP_ENTRY_FOREACH(entry, map) {
|
|
if ((entry->eflags & MAP_ENTRY_IS_SUB_MAP) != 0)
|
|
continue;
|
|
obj = entry->object.vm_object;
|
|
if (obj == NULL)
|
|
continue;
|
|
if ((entry->eflags & MAP_ENTRY_NEEDS_COPY) != 0 &&
|
|
obj->ref_count != 1)
|
|
continue;
|
|
if (obj->type == OBJT_PHYS || obj->type == OBJT_VNODE ||
|
|
(obj->flags & OBJ_SWAP) != 0)
|
|
res += obj->resident_page_count;
|
|
}
|
|
return (res);
|
|
}
|
|
|
|
static int vm_oom_ratelim_last;
|
|
static int vm_oom_pf_secs = 10;
|
|
SYSCTL_INT(_vm, OID_AUTO, oom_pf_secs, CTLFLAG_RWTUN, &vm_oom_pf_secs, 0,
|
|
"");
|
|
static struct mtx vm_oom_ratelim_mtx;
|
|
|
|
void
|
|
vm_pageout_oom(int shortage)
|
|
{
|
|
const char *reason;
|
|
struct proc *p, *bigproc;
|
|
vm_offset_t size, bigsize;
|
|
struct thread *td;
|
|
struct vmspace *vm;
|
|
int now;
|
|
bool breakout;
|
|
|
|
/*
|
|
* For OOM requests originating from vm_fault(), there is a high
|
|
* chance that a single large process faults simultaneously in
|
|
* several threads. Also, on an active system running many
|
|
* processes of middle-size, like buildworld, all of them
|
|
* could fault almost simultaneously as well.
|
|
*
|
|
* To avoid killing too many processes, rate-limit OOMs
|
|
* initiated by vm_fault() time-outs on the waits for free
|
|
* pages.
|
|
*/
|
|
mtx_lock(&vm_oom_ratelim_mtx);
|
|
now = ticks;
|
|
if (shortage == VM_OOM_MEM_PF &&
|
|
(u_int)(now - vm_oom_ratelim_last) < hz * vm_oom_pf_secs) {
|
|
mtx_unlock(&vm_oom_ratelim_mtx);
|
|
return;
|
|
}
|
|
vm_oom_ratelim_last = now;
|
|
mtx_unlock(&vm_oom_ratelim_mtx);
|
|
|
|
/*
|
|
* We keep the process bigproc locked once we find it to keep anyone
|
|
* from messing with it; however, there is a possibility of
|
|
* deadlock if process B is bigproc and one of its child processes
|
|
* attempts to propagate a signal to B while we are waiting for A's
|
|
* lock while walking this list. To avoid this, we don't block on
|
|
* the process lock but just skip a process if it is already locked.
|
|
*/
|
|
bigproc = NULL;
|
|
bigsize = 0;
|
|
sx_slock(&allproc_lock);
|
|
FOREACH_PROC_IN_SYSTEM(p) {
|
|
PROC_LOCK(p);
|
|
|
|
/*
|
|
* If this is a system, protected or killed process, skip it.
|
|
*/
|
|
if (p->p_state != PRS_NORMAL || (p->p_flag & (P_INEXEC |
|
|
P_PROTECTED | P_SYSTEM | P_WEXIT)) != 0 ||
|
|
p->p_pid == 1 || P_KILLED(p) ||
|
|
(p->p_pid < 48 && swap_pager_avail != 0)) {
|
|
PROC_UNLOCK(p);
|
|
continue;
|
|
}
|
|
/*
|
|
* If the process is in a non-running type state,
|
|
* don't touch it. Check all the threads individually.
|
|
*/
|
|
breakout = false;
|
|
FOREACH_THREAD_IN_PROC(p, td) {
|
|
thread_lock(td);
|
|
if (!TD_ON_RUNQ(td) &&
|
|
!TD_IS_RUNNING(td) &&
|
|
!TD_IS_SLEEPING(td) &&
|
|
!TD_IS_SUSPENDED(td) &&
|
|
!TD_IS_SWAPPED(td)) {
|
|
thread_unlock(td);
|
|
breakout = true;
|
|
break;
|
|
}
|
|
thread_unlock(td);
|
|
}
|
|
if (breakout) {
|
|
PROC_UNLOCK(p);
|
|
continue;
|
|
}
|
|
/*
|
|
* get the process size
|
|
*/
|
|
vm = vmspace_acquire_ref(p);
|
|
if (vm == NULL) {
|
|
PROC_UNLOCK(p);
|
|
continue;
|
|
}
|
|
_PHOLD_LITE(p);
|
|
PROC_UNLOCK(p);
|
|
sx_sunlock(&allproc_lock);
|
|
if (!vm_map_trylock_read(&vm->vm_map)) {
|
|
vmspace_free(vm);
|
|
sx_slock(&allproc_lock);
|
|
PRELE(p);
|
|
continue;
|
|
}
|
|
size = vmspace_swap_count(vm);
|
|
if (shortage == VM_OOM_MEM || shortage == VM_OOM_MEM_PF)
|
|
size += vm_pageout_oom_pagecount(vm);
|
|
vm_map_unlock_read(&vm->vm_map);
|
|
vmspace_free(vm);
|
|
sx_slock(&allproc_lock);
|
|
|
|
/*
|
|
* If this process is bigger than the biggest one,
|
|
* remember it.
|
|
*/
|
|
if (size > bigsize) {
|
|
if (bigproc != NULL)
|
|
PRELE(bigproc);
|
|
bigproc = p;
|
|
bigsize = size;
|
|
} else {
|
|
PRELE(p);
|
|
}
|
|
}
|
|
sx_sunlock(&allproc_lock);
|
|
|
|
if (bigproc != NULL) {
|
|
switch (shortage) {
|
|
case VM_OOM_MEM:
|
|
reason = "failed to reclaim memory";
|
|
break;
|
|
case VM_OOM_MEM_PF:
|
|
reason = "a thread waited too long to allocate a page";
|
|
break;
|
|
case VM_OOM_SWAPZ:
|
|
reason = "out of swap space";
|
|
break;
|
|
default:
|
|
panic("unknown OOM reason %d", shortage);
|
|
}
|
|
if (vm_panic_on_oom != 0 && --vm_panic_on_oom == 0)
|
|
panic("%s", reason);
|
|
PROC_LOCK(bigproc);
|
|
killproc(bigproc, reason);
|
|
sched_nice(bigproc, PRIO_MIN);
|
|
_PRELE(bigproc);
|
|
PROC_UNLOCK(bigproc);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Signal a free page shortage to subsystems that have registered an event
|
|
* handler. Reclaim memory from UMA in the event of a severe shortage.
|
|
* Return true if the free page count should be re-evaluated.
|
|
*/
|
|
static bool
|
|
vm_pageout_lowmem(void)
|
|
{
|
|
static int lowmem_ticks = 0;
|
|
int last;
|
|
bool ret;
|
|
|
|
ret = false;
|
|
|
|
last = atomic_load_int(&lowmem_ticks);
|
|
while ((u_int)(ticks - last) / hz >= lowmem_period) {
|
|
if (atomic_fcmpset_int(&lowmem_ticks, &last, ticks) == 0)
|
|
continue;
|
|
|
|
/*
|
|
* Decrease registered cache sizes.
|
|
*/
|
|
SDT_PROBE0(vm, , , vm__lowmem_scan);
|
|
EVENTHANDLER_INVOKE(vm_lowmem, VM_LOW_PAGES);
|
|
|
|
/*
|
|
* We do this explicitly after the caches have been
|
|
* drained above.
|
|
*/
|
|
uma_reclaim(UMA_RECLAIM_TRIM);
|
|
ret = true;
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* Kick off an asynchronous reclaim of cached memory if one of the
|
|
* page daemons is failing to keep up with demand. Use the "severe"
|
|
* threshold instead of "min" to ensure that we do not blow away the
|
|
* caches if a subset of the NUMA domains are depleted by kernel memory
|
|
* allocations; the domainset iterators automatically skip domains
|
|
* below the "min" threshold on the first pass.
|
|
*
|
|
* UMA reclaim worker has its own rate-limiting mechanism, so don't
|
|
* worry about kicking it too often.
|
|
*/
|
|
if (vm_page_count_severe())
|
|
uma_reclaim_wakeup();
|
|
|
|
return (ret);
|
|
}
|
|
|
|
static void
|
|
vm_pageout_worker(void *arg)
|
|
{
|
|
struct vm_domain *vmd;
|
|
u_int ofree;
|
|
int addl_shortage, domain, shortage;
|
|
bool target_met;
|
|
|
|
domain = (uintptr_t)arg;
|
|
vmd = VM_DOMAIN(domain);
|
|
shortage = 0;
|
|
target_met = true;
|
|
|
|
/*
|
|
* XXXKIB It could be useful to bind pageout daemon threads to
|
|
* the cores belonging to the domain, from which vm_page_array
|
|
* is allocated.
|
|
*/
|
|
|
|
KASSERT(vmd->vmd_segs != 0, ("domain without segments"));
|
|
vmd->vmd_last_active_scan = ticks;
|
|
|
|
/*
|
|
* The pageout daemon worker is never done, so loop forever.
|
|
*/
|
|
while (TRUE) {
|
|
vm_domain_pageout_lock(vmd);
|
|
|
|
/*
|
|
* We need to clear wanted before we check the limits. This
|
|
* prevents races with wakers who will check wanted after they
|
|
* reach the limit.
|
|
*/
|
|
atomic_store_int(&vmd->vmd_pageout_wanted, 0);
|
|
|
|
/*
|
|
* Might the page daemon need to run again?
|
|
*/
|
|
if (vm_paging_needed(vmd, vmd->vmd_free_count)) {
|
|
/*
|
|
* Yes. If the scan failed to produce enough free
|
|
* pages, sleep uninterruptibly for some time in the
|
|
* hope that the laundry thread will clean some pages.
|
|
*/
|
|
vm_domain_pageout_unlock(vmd);
|
|
if (!target_met)
|
|
pause("pwait", hz / VM_INACT_SCAN_RATE);
|
|
} else {
|
|
/*
|
|
* No, sleep until the next wakeup or until pages
|
|
* need to have their reference stats updated.
|
|
*/
|
|
if (mtx_sleep(&vmd->vmd_pageout_wanted,
|
|
vm_domain_pageout_lockptr(vmd), PDROP | PVM,
|
|
"psleep", hz / VM_INACT_SCAN_RATE) == 0)
|
|
VM_CNT_INC(v_pdwakeups);
|
|
}
|
|
|
|
/* Prevent spurious wakeups by ensuring that wanted is set. */
|
|
atomic_store_int(&vmd->vmd_pageout_wanted, 1);
|
|
|
|
/*
|
|
* Use the controller to calculate how many pages to free in
|
|
* this interval, and scan the inactive queue. If the lowmem
|
|
* handlers appear to have freed up some pages, subtract the
|
|
* difference from the inactive queue scan target.
|
|
*/
|
|
shortage = pidctrl_daemon(&vmd->vmd_pid, vmd->vmd_free_count);
|
|
if (shortage > 0) {
|
|
ofree = vmd->vmd_free_count;
|
|
if (vm_pageout_lowmem() && vmd->vmd_free_count > ofree)
|
|
shortage -= min(vmd->vmd_free_count - ofree,
|
|
(u_int)shortage);
|
|
target_met = vm_pageout_inactive(vmd, shortage,
|
|
&addl_shortage);
|
|
} else
|
|
addl_shortage = 0;
|
|
|
|
/*
|
|
* Scan the active queue. A positive value for shortage
|
|
* indicates that we must aggressively deactivate pages to avoid
|
|
* a shortfall.
|
|
*/
|
|
shortage = vm_pageout_active_target(vmd) + addl_shortage;
|
|
vm_pageout_scan_active(vmd, shortage);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* vm_pageout_helper runs additional pageout daemons in times of high paging
|
|
* activity.
|
|
*/
|
|
static void
|
|
vm_pageout_helper(void *arg)
|
|
{
|
|
struct vm_domain *vmd;
|
|
int domain;
|
|
|
|
domain = (uintptr_t)arg;
|
|
vmd = VM_DOMAIN(domain);
|
|
|
|
vm_domain_pageout_lock(vmd);
|
|
for (;;) {
|
|
msleep(&vmd->vmd_inactive_shortage,
|
|
vm_domain_pageout_lockptr(vmd), PVM, "psleep", 0);
|
|
blockcount_release(&vmd->vmd_inactive_starting, 1);
|
|
|
|
vm_domain_pageout_unlock(vmd);
|
|
vm_pageout_scan_inactive(vmd, vmd->vmd_inactive_shortage);
|
|
vm_domain_pageout_lock(vmd);
|
|
|
|
/*
|
|
* Release the running count while the pageout lock is held to
|
|
* prevent wakeup races.
|
|
*/
|
|
blockcount_release(&vmd->vmd_inactive_running, 1);
|
|
}
|
|
}
|
|
|
|
static int
|
|
get_pageout_threads_per_domain(const struct vm_domain *vmd)
|
|
{
|
|
unsigned total_pageout_threads, eligible_cpus, domain_cpus;
|
|
|
|
if (VM_DOMAIN_EMPTY(vmd->vmd_domain))
|
|
return (0);
|
|
|
|
/*
|
|
* Semi-arbitrarily constrain pagedaemon threads to less than half the
|
|
* total number of CPUs in the system as an upper limit.
|
|
*/
|
|
if (pageout_cpus_per_thread < 2)
|
|
pageout_cpus_per_thread = 2;
|
|
else if (pageout_cpus_per_thread > mp_ncpus)
|
|
pageout_cpus_per_thread = mp_ncpus;
|
|
|
|
total_pageout_threads = howmany(mp_ncpus, pageout_cpus_per_thread);
|
|
domain_cpus = CPU_COUNT(&cpuset_domain[vmd->vmd_domain]);
|
|
|
|
/* Pagedaemons are not run in empty domains. */
|
|
eligible_cpus = mp_ncpus;
|
|
for (unsigned i = 0; i < vm_ndomains; i++)
|
|
if (VM_DOMAIN_EMPTY(i))
|
|
eligible_cpus -= CPU_COUNT(&cpuset_domain[i]);
|
|
|
|
/*
|
|
* Assign a portion of the total pageout threads to this domain
|
|
* corresponding to the fraction of pagedaemon-eligible CPUs in the
|
|
* domain. In asymmetric NUMA systems, domains with more CPUs may be
|
|
* allocated more threads than domains with fewer CPUs.
|
|
*/
|
|
return (howmany(total_pageout_threads * domain_cpus, eligible_cpus));
|
|
}
|
|
|
|
/*
|
|
* Initialize basic pageout daemon settings. See the comment above the
|
|
* definition of vm_domain for some explanation of how these thresholds are
|
|
* used.
|
|
*/
|
|
static void
|
|
vm_pageout_init_domain(int domain)
|
|
{
|
|
struct vm_domain *vmd;
|
|
struct sysctl_oid *oid;
|
|
|
|
vmd = VM_DOMAIN(domain);
|
|
vmd->vmd_interrupt_free_min = 2;
|
|
|
|
/*
|
|
* v_free_reserved needs to include enough for the largest
|
|
* swap pager structures plus enough for any pv_entry structs
|
|
* when paging.
|
|
*/
|
|
vmd->vmd_pageout_free_min = 2 * MAXBSIZE / PAGE_SIZE +
|
|
vmd->vmd_interrupt_free_min;
|
|
vmd->vmd_free_reserved = vm_pageout_page_count +
|
|
vmd->vmd_pageout_free_min + vmd->vmd_page_count / 768;
|
|
vmd->vmd_free_min = vmd->vmd_page_count / 200;
|
|
vmd->vmd_free_severe = vmd->vmd_free_min / 2;
|
|
vmd->vmd_free_target = 4 * vmd->vmd_free_min + vmd->vmd_free_reserved;
|
|
vmd->vmd_free_min += vmd->vmd_free_reserved;
|
|
vmd->vmd_free_severe += vmd->vmd_free_reserved;
|
|
vmd->vmd_inactive_target = (3 * vmd->vmd_free_target) / 2;
|
|
if (vmd->vmd_inactive_target > vmd->vmd_free_count / 3)
|
|
vmd->vmd_inactive_target = vmd->vmd_free_count / 3;
|
|
|
|
/*
|
|
* Set the default wakeup threshold to be 10% below the paging
|
|
* target. This keeps the steady state out of shortfall.
|
|
*/
|
|
vmd->vmd_pageout_wakeup_thresh = (vmd->vmd_free_target / 10) * 9;
|
|
|
|
/*
|
|
* Target amount of memory to move out of the laundry queue during a
|
|
* background laundering. This is proportional to the amount of system
|
|
* memory.
|
|
*/
|
|
vmd->vmd_background_launder_target = (vmd->vmd_free_target -
|
|
vmd->vmd_free_min) / 10;
|
|
|
|
/* Initialize the pageout daemon pid controller. */
|
|
pidctrl_init(&vmd->vmd_pid, hz / VM_INACT_SCAN_RATE,
|
|
vmd->vmd_free_target, PIDCTRL_BOUND,
|
|
PIDCTRL_KPD, PIDCTRL_KID, PIDCTRL_KDD);
|
|
oid = SYSCTL_ADD_NODE(NULL, SYSCTL_CHILDREN(vmd->vmd_oid), OID_AUTO,
|
|
"pidctrl", CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, "");
|
|
pidctrl_init_sysctl(&vmd->vmd_pid, SYSCTL_CHILDREN(oid));
|
|
|
|
vmd->vmd_inactive_threads = get_pageout_threads_per_domain(vmd);
|
|
}
|
|
|
|
static void
|
|
vm_pageout_init(void)
|
|
{
|
|
u_long freecount;
|
|
int i;
|
|
|
|
/*
|
|
* Initialize some paging parameters.
|
|
*/
|
|
if (vm_cnt.v_page_count < 2000)
|
|
vm_pageout_page_count = 8;
|
|
|
|
freecount = 0;
|
|
for (i = 0; i < vm_ndomains; i++) {
|
|
struct vm_domain *vmd;
|
|
|
|
vm_pageout_init_domain(i);
|
|
vmd = VM_DOMAIN(i);
|
|
vm_cnt.v_free_reserved += vmd->vmd_free_reserved;
|
|
vm_cnt.v_free_target += vmd->vmd_free_target;
|
|
vm_cnt.v_free_min += vmd->vmd_free_min;
|
|
vm_cnt.v_inactive_target += vmd->vmd_inactive_target;
|
|
vm_cnt.v_pageout_free_min += vmd->vmd_pageout_free_min;
|
|
vm_cnt.v_interrupt_free_min += vmd->vmd_interrupt_free_min;
|
|
vm_cnt.v_free_severe += vmd->vmd_free_severe;
|
|
freecount += vmd->vmd_free_count;
|
|
}
|
|
|
|
/*
|
|
* Set interval in seconds for active scan. We want to visit each
|
|
* page at least once every ten minutes. This is to prevent worst
|
|
* case paging behaviors with stale active LRU.
|
|
*/
|
|
if (vm_pageout_update_period == 0)
|
|
vm_pageout_update_period = 600;
|
|
|
|
/*
|
|
* Set the maximum number of user-wired virtual pages. Historically the
|
|
* main source of such pages was mlock(2) and mlockall(2). Hypervisors
|
|
* may also request user-wired memory.
|
|
*/
|
|
if (vm_page_max_user_wired == 0)
|
|
vm_page_max_user_wired = 4 * freecount / 5;
|
|
}
|
|
|
|
/*
|
|
* vm_pageout is the high level pageout daemon.
|
|
*/
|
|
static void
|
|
vm_pageout(void)
|
|
{
|
|
struct proc *p;
|
|
struct thread *td;
|
|
int error, first, i, j, pageout_threads;
|
|
|
|
p = curproc;
|
|
td = curthread;
|
|
|
|
mtx_init(&vm_oom_ratelim_mtx, "vmoomr", NULL, MTX_DEF);
|
|
swap_pager_swap_init();
|
|
for (first = -1, i = 0; i < vm_ndomains; i++) {
|
|
if (VM_DOMAIN_EMPTY(i)) {
|
|
if (bootverbose)
|
|
printf("domain %d empty; skipping pageout\n",
|
|
i);
|
|
continue;
|
|
}
|
|
if (first == -1)
|
|
first = i;
|
|
else {
|
|
error = kthread_add(vm_pageout_worker,
|
|
(void *)(uintptr_t)i, p, NULL, 0, 0, "dom%d", i);
|
|
if (error != 0)
|
|
panic("starting pageout for domain %d: %d\n",
|
|
i, error);
|
|
}
|
|
pageout_threads = VM_DOMAIN(i)->vmd_inactive_threads;
|
|
for (j = 0; j < pageout_threads - 1; j++) {
|
|
error = kthread_add(vm_pageout_helper,
|
|
(void *)(uintptr_t)i, p, NULL, 0, 0,
|
|
"dom%d helper%d", i, j);
|
|
if (error != 0)
|
|
panic("starting pageout helper %d for domain "
|
|
"%d: %d\n", j, i, error);
|
|
}
|
|
error = kthread_add(vm_pageout_laundry_worker,
|
|
(void *)(uintptr_t)i, p, NULL, 0, 0, "laundry: dom%d", i);
|
|
if (error != 0)
|
|
panic("starting laundry for domain %d: %d", i, error);
|
|
}
|
|
error = kthread_add(uma_reclaim_worker, NULL, p, NULL, 0, 0, "uma");
|
|
if (error != 0)
|
|
panic("starting uma_reclaim helper, error %d\n", error);
|
|
|
|
snprintf(td->td_name, sizeof(td->td_name), "dom%d", first);
|
|
vm_pageout_worker((void *)(uintptr_t)first);
|
|
}
|
|
|
|
/*
|
|
* Perform an advisory wakeup of the page daemon.
|
|
*/
|
|
void
|
|
pagedaemon_wakeup(int domain)
|
|
{
|
|
struct vm_domain *vmd;
|
|
|
|
vmd = VM_DOMAIN(domain);
|
|
vm_domain_pageout_assert_unlocked(vmd);
|
|
if (curproc == pageproc)
|
|
return;
|
|
|
|
if (atomic_fetchadd_int(&vmd->vmd_pageout_wanted, 1) == 0) {
|
|
vm_domain_pageout_lock(vmd);
|
|
atomic_store_int(&vmd->vmd_pageout_wanted, 1);
|
|
wakeup(&vmd->vmd_pageout_wanted);
|
|
vm_domain_pageout_unlock(vmd);
|
|
}
|
|
}
|