6fcf6199a4
To reduce the diff struct pcu.cnt field was not renamed, so PCPU_OP(cnt.field) is still used. pc_cnt and pcpu are also used in kvm(3) and vmstat(8). The goal was to not affect externally used KPI. Bump __FreeBSD_version_ in case some out-of-tree module/code relies on the the global cnt variable. Exp-run revealed no ports using it directly. No objection from: arch@ Sponsored by: EMC / Isilon Storage Division
1877 lines
51 KiB
C
1877 lines
51 KiB
C
/*-
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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/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/signalvar.h>
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#include <sys/smp.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/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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* System initialization
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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 int vm_pageout_clean(vm_page_t);
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static void vm_pageout_scan(struct vm_domain *vmd, int pass);
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static void vm_pageout_mightbe_oom(struct vm_domain *vmd, int pass);
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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_FIRST, kproc_start,
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&page_kp);
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#if !defined(NO_SWAPPING)
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/* the kernel process "vm_daemon"*/
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static void vm_daemon(void);
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static struct proc *vmproc;
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static struct kproc_desc vm_kp = {
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"vmdaemon",
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vm_daemon,
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&vmproc
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};
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SYSINIT(vmdaemon, SI_SUB_KTHREAD_VM, SI_ORDER_FIRST, kproc_start, &vm_kp);
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#endif
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|
|
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int vm_pages_needed; /* Event on which pageout daemon sleeps */
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int vm_pageout_deficit; /* Estimated number of pages deficit */
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int vm_pageout_pages_needed; /* flag saying that the pageout daemon needs pages */
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int vm_pageout_wakeup_thresh;
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#if !defined(NO_SWAPPING)
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static int vm_pageout_req_swapout; /* XXX */
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static int vm_daemon_needed;
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static struct mtx vm_daemon_mtx;
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/* Allow for use by vm_pageout before vm_daemon is initialized. */
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MTX_SYSINIT(vm_daemon, &vm_daemon_mtx, "vm daemon", MTX_DEF);
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#endif
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static int vm_max_launder = 32;
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static int vm_pageout_update_period;
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static int defer_swap_pageouts;
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static int disable_swap_pageouts;
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static int lowmem_period = 10;
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static int lowmem_ticks;
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#if defined(NO_SWAPPING)
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static int vm_swap_enabled = 0;
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static int vm_swap_idle_enabled = 0;
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#else
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static int vm_swap_enabled = 1;
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static int vm_swap_idle_enabled = 0;
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#endif
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SYSCTL_INT(_vm, OID_AUTO, pageout_wakeup_thresh,
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CTLFLAG_RW, &vm_pageout_wakeup_thresh, 0,
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"free page threshold for waking up the pageout daemon");
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SYSCTL_INT(_vm, OID_AUTO, max_launder,
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CTLFLAG_RW, &vm_max_launder, 0, "Limit dirty flushes in pageout");
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SYSCTL_INT(_vm, OID_AUTO, pageout_update_period,
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CTLFLAG_RW, &vm_pageout_update_period, 0,
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"Maximum active LRU update period");
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SYSCTL_INT(_vm, OID_AUTO, lowmem_period, CTLFLAG_RW, &lowmem_period, 0,
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"Low memory callback period");
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#if defined(NO_SWAPPING)
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SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled,
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CTLFLAG_RD, &vm_swap_enabled, 0, "Enable entire process swapout");
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SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled,
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CTLFLAG_RD, &vm_swap_idle_enabled, 0, "Allow swapout on idle criteria");
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#else
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SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled,
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CTLFLAG_RW, &vm_swap_enabled, 0, "Enable entire process swapout");
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SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled,
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CTLFLAG_RW, &vm_swap_idle_enabled, 0, "Allow swapout on idle criteria");
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#endif
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SYSCTL_INT(_vm, OID_AUTO, defer_swapspace_pageouts,
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CTLFLAG_RW, &defer_swap_pageouts, 0, "Give preference to dirty pages in mem");
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SYSCTL_INT(_vm, OID_AUTO, disable_swapspace_pageouts,
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CTLFLAG_RW, &disable_swap_pageouts, 0, "Disallow swapout of dirty pages");
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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, "vget() lock misses during pageout");
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#define VM_PAGEOUT_PAGE_COUNT 16
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int vm_pageout_page_count = VM_PAGEOUT_PAGE_COUNT;
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int vm_page_max_wired; /* XXX max # of wired pages system-wide */
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SYSCTL_INT(_vm, OID_AUTO, max_wired,
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CTLFLAG_RW, &vm_page_max_wired, 0, "System-wide limit to wired page count");
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static boolean_t vm_pageout_fallback_object_lock(vm_page_t, vm_page_t *);
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static boolean_t vm_pageout_launder(struct vm_pagequeue *pq, int, vm_paddr_t,
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vm_paddr_t);
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#if !defined(NO_SWAPPING)
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static void vm_pageout_map_deactivate_pages(vm_map_t, long);
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static void vm_pageout_object_deactivate_pages(pmap_t, vm_object_t, long);
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static void vm_req_vmdaemon(int req);
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#endif
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static boolean_t vm_pageout_page_lock(vm_page_t, vm_page_t *);
|
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/*
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|
* Initialize a dummy page for marking the caller's place in the specified
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* paging queue. In principle, this function only needs to set the flag
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* PG_MARKER. Nonetheless, it wirte busies and initializes the hold count
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* to one as safety precautions.
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*/
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static void
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vm_pageout_init_marker(vm_page_t marker, u_short queue)
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{
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bzero(marker, sizeof(*marker));
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marker->flags = PG_MARKER;
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marker->busy_lock = VPB_SINGLE_EXCLUSIVER;
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marker->queue = queue;
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marker->hold_count = 1;
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}
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/*
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* vm_pageout_fallback_object_lock:
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*
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* Lock vm object currently associated with `m'. VM_OBJECT_TRYWLOCK is
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* known to have failed and page queue must be either PQ_ACTIVE or
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* PQ_INACTIVE. To avoid lock order violation, unlock the page queues
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* while locking the vm object. Use marker page to detect page queue
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* changes and maintain notion of next page on page queue. Return
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* TRUE if no changes were detected, FALSE otherwise. vm object is
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* locked on return.
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*
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* This function depends on both the lock portion of struct vm_object
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* and normal struct vm_page being type stable.
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*/
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static boolean_t
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vm_pageout_fallback_object_lock(vm_page_t m, vm_page_t *next)
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{
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struct vm_page marker;
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struct vm_pagequeue *pq;
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boolean_t unchanged;
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u_short queue;
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vm_object_t object;
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queue = m->queue;
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vm_pageout_init_marker(&marker, queue);
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pq = vm_page_pagequeue(m);
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object = m->object;
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TAILQ_INSERT_AFTER(&pq->pq_pl, m, &marker, plinks.q);
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vm_pagequeue_unlock(pq);
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vm_page_unlock(m);
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VM_OBJECT_WLOCK(object);
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vm_page_lock(m);
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vm_pagequeue_lock(pq);
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/* Page queue might have changed. */
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*next = TAILQ_NEXT(&marker, plinks.q);
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unchanged = (m->queue == queue &&
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m->object == object &&
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&marker == TAILQ_NEXT(m, plinks.q));
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TAILQ_REMOVE(&pq->pq_pl, &marker, plinks.q);
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return (unchanged);
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}
|
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|
|
/*
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* Lock the page while holding the page queue lock. Use marker page
|
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* to detect page queue changes and maintain notion of next page on
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* page queue. Return TRUE if no changes were detected, FALSE
|
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* otherwise. The page is locked on return. The page queue lock might
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* be dropped and reacquired.
|
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*
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* This function depends on normal struct vm_page being type stable.
|
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*/
|
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static boolean_t
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vm_pageout_page_lock(vm_page_t m, vm_page_t *next)
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{
|
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struct vm_page marker;
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struct vm_pagequeue *pq;
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boolean_t unchanged;
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u_short queue;
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|
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vm_page_lock_assert(m, MA_NOTOWNED);
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if (vm_page_trylock(m))
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return (TRUE);
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queue = m->queue;
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vm_pageout_init_marker(&marker, queue);
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pq = vm_page_pagequeue(m);
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TAILQ_INSERT_AFTER(&pq->pq_pl, m, &marker, plinks.q);
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vm_pagequeue_unlock(pq);
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vm_page_lock(m);
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vm_pagequeue_lock(pq);
|
|
|
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/* Page queue might have changed. */
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*next = TAILQ_NEXT(&marker, plinks.q);
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unchanged = (m->queue == queue && &marker == TAILQ_NEXT(m, plinks.q));
|
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TAILQ_REMOVE(&pq->pq_pl, &marker, plinks.q);
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return (unchanged);
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}
|
|
|
|
/*
|
|
* vm_pageout_clean:
|
|
*
|
|
* Clean the page and remove it from the laundry.
|
|
*
|
|
* We set the busy bit to cause potential page faults on this page to
|
|
* block. Note the careful timing, however, the busy bit isn't set till
|
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* late and we cannot do anything that will mess with the page.
|
|
*/
|
|
static int
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vm_pageout_clean(vm_page_t m)
|
|
{
|
|
vm_object_t object;
|
|
vm_page_t mc[2*vm_pageout_page_count], pb, ps;
|
|
int pageout_count;
|
|
int ib, is, page_base;
|
|
vm_pindex_t pindex = m->pindex;
|
|
|
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vm_page_lock_assert(m, MA_OWNED);
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object = m->object;
|
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VM_OBJECT_ASSERT_WLOCKED(object);
|
|
|
|
/*
|
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* It doesn't cost us anything to pageout OBJT_DEFAULT or OBJT_SWAP
|
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* with the new swapper, but we could have serious problems paging
|
|
* out other object types if there is insufficient memory.
|
|
*
|
|
* Unfortunately, checking free memory here is far too late, so the
|
|
* check has been moved up a procedural level.
|
|
*/
|
|
|
|
/*
|
|
* Can't clean the page if it's busy or held.
|
|
*/
|
|
vm_page_assert_unbusied(m);
|
|
KASSERT(m->hold_count == 0, ("vm_pageout_clean: page %p is held", m));
|
|
vm_page_unlock(m);
|
|
|
|
mc[vm_pageout_page_count] = pb = ps = m;
|
|
pageout_count = 1;
|
|
page_base = vm_pageout_page_count;
|
|
ib = 1;
|
|
is = 1;
|
|
|
|
/*
|
|
* Scan object for clusterable pages.
|
|
*
|
|
* We can cluster ONLY if: ->> the page is NOT
|
|
* clean, wired, busy, held, or mapped into a
|
|
* buffer, and one of the following:
|
|
* 1) The page is inactive, or a seldom used
|
|
* active page.
|
|
* -or-
|
|
* 2) we force the issue.
|
|
*
|
|
* During heavy mmap/modification loads the pageout
|
|
* daemon can really fragment the underlying file
|
|
* due to flushing pages out of order and not trying
|
|
* align the clusters (which leave sporatic 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 && pageout_count < vm_pageout_page_count) {
|
|
vm_page_t p;
|
|
|
|
if (ib > pindex) {
|
|
ib = 0;
|
|
break;
|
|
}
|
|
|
|
if ((p = vm_page_prev(pb)) == NULL || vm_page_busied(p)) {
|
|
ib = 0;
|
|
break;
|
|
}
|
|
vm_page_lock(p);
|
|
vm_page_test_dirty(p);
|
|
if (p->dirty == 0 ||
|
|
p->queue != PQ_INACTIVE ||
|
|
p->hold_count != 0) { /* may be undergoing I/O */
|
|
vm_page_unlock(p);
|
|
ib = 0;
|
|
break;
|
|
}
|
|
vm_page_unlock(p);
|
|
mc[--page_base] = pb = p;
|
|
++pageout_count;
|
|
++ib;
|
|
/*
|
|
* alignment boundry, 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) {
|
|
vm_page_t p;
|
|
|
|
if ((p = vm_page_next(ps)) == NULL || vm_page_busied(p))
|
|
break;
|
|
vm_page_lock(p);
|
|
vm_page_test_dirty(p);
|
|
if (p->dirty == 0 ||
|
|
p->queue != PQ_INACTIVE ||
|
|
p->hold_count != 0) { /* may be undergoing I/O */
|
|
vm_page_unlock(p);
|
|
break;
|
|
}
|
|
vm_page_unlock(p);
|
|
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 a page boundry. This catches boundry
|
|
* conditions.
|
|
*/
|
|
if (ib && pageout_count < vm_pageout_page_count)
|
|
goto more;
|
|
|
|
/*
|
|
* we allow reads during pageouts...
|
|
*/
|
|
return (vm_pageout_flush(&mc[page_base], pageout_count, 0, 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. Bump the vm_page_t->busy counter and
|
|
* mark the pages 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(mc[i]->valid == VM_PAGE_BITS_ALL,
|
|
("vm_pageout_flush: partially invalid page %p index %d/%d",
|
|
mc[i], i, count));
|
|
vm_page_sbusy(mc[i]);
|
|
pmap_remove_write(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:
|
|
case VM_PAGER_PEND:
|
|
numpagedout++;
|
|
break;
|
|
case VM_PAGER_BAD:
|
|
/*
|
|
* Page outside of range of object. Right now we
|
|
* essentially lose the changes by pretending it
|
|
* worked.
|
|
*/
|
|
vm_page_undirty(mt);
|
|
break;
|
|
case VM_PAGER_ERROR:
|
|
case VM_PAGER_FAIL:
|
|
/*
|
|
* If page couldn't be paged out, then reactivate the
|
|
* page so it doesn't clog the inactive list. (We
|
|
* will try paging out it again later).
|
|
*/
|
|
vm_page_lock(mt);
|
|
vm_page_activate(mt);
|
|
vm_page_unlock(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 (vm_page_count_severe()) {
|
|
vm_page_lock(mt);
|
|
vm_page_try_to_cache(mt);
|
|
vm_page_unlock(mt);
|
|
}
|
|
}
|
|
}
|
|
if (prunlen != NULL)
|
|
*prunlen = runlen;
|
|
return (numpagedout);
|
|
}
|
|
|
|
static boolean_t
|
|
vm_pageout_launder(struct vm_pagequeue *pq, int tries, vm_paddr_t low,
|
|
vm_paddr_t high)
|
|
{
|
|
struct mount *mp;
|
|
struct vnode *vp;
|
|
vm_object_t object;
|
|
vm_paddr_t pa;
|
|
vm_page_t m, m_tmp, next;
|
|
int lockmode;
|
|
|
|
vm_pagequeue_lock(pq);
|
|
TAILQ_FOREACH_SAFE(m, &pq->pq_pl, plinks.q, next) {
|
|
if ((m->flags & PG_MARKER) != 0)
|
|
continue;
|
|
pa = VM_PAGE_TO_PHYS(m);
|
|
if (pa < low || pa + PAGE_SIZE > high)
|
|
continue;
|
|
if (!vm_pageout_page_lock(m, &next) || m->hold_count != 0) {
|
|
vm_page_unlock(m);
|
|
continue;
|
|
}
|
|
object = m->object;
|
|
if ((!VM_OBJECT_TRYWLOCK(object) &&
|
|
(!vm_pageout_fallback_object_lock(m, &next) ||
|
|
m->hold_count != 0)) || vm_page_busied(m)) {
|
|
vm_page_unlock(m);
|
|
VM_OBJECT_WUNLOCK(object);
|
|
continue;
|
|
}
|
|
vm_page_test_dirty(m);
|
|
if (m->dirty == 0 && object->ref_count != 0)
|
|
pmap_remove_all(m);
|
|
if (m->dirty != 0) {
|
|
vm_page_unlock(m);
|
|
if (tries == 0 || (object->flags & OBJ_DEAD) != 0) {
|
|
VM_OBJECT_WUNLOCK(object);
|
|
continue;
|
|
}
|
|
if (object->type == OBJT_VNODE) {
|
|
vm_pagequeue_unlock(pq);
|
|
vp = object->handle;
|
|
vm_object_reference_locked(object);
|
|
VM_OBJECT_WUNLOCK(object);
|
|
(void)vn_start_write(vp, &mp, V_WAIT);
|
|
lockmode = MNT_SHARED_WRITES(vp->v_mount) ?
|
|
LK_SHARED : LK_EXCLUSIVE;
|
|
vn_lock(vp, lockmode | LK_RETRY);
|
|
VM_OBJECT_WLOCK(object);
|
|
vm_object_page_clean(object, 0, 0, OBJPC_SYNC);
|
|
VM_OBJECT_WUNLOCK(object);
|
|
VOP_UNLOCK(vp, 0);
|
|
vm_object_deallocate(object);
|
|
vn_finished_write(mp);
|
|
return (TRUE);
|
|
} else if (object->type == OBJT_SWAP ||
|
|
object->type == OBJT_DEFAULT) {
|
|
vm_pagequeue_unlock(pq);
|
|
m_tmp = m;
|
|
vm_pageout_flush(&m_tmp, 1, VM_PAGER_PUT_SYNC,
|
|
0, NULL, NULL);
|
|
VM_OBJECT_WUNLOCK(object);
|
|
return (TRUE);
|
|
}
|
|
} else {
|
|
/*
|
|
* Dequeue here to prevent lock recursion in
|
|
* vm_page_cache().
|
|
*/
|
|
vm_page_dequeue_locked(m);
|
|
vm_page_cache(m);
|
|
vm_page_unlock(m);
|
|
}
|
|
VM_OBJECT_WUNLOCK(object);
|
|
}
|
|
vm_pagequeue_unlock(pq);
|
|
return (FALSE);
|
|
}
|
|
|
|
/*
|
|
* Increase the number of cached pages. The specified value, "tries",
|
|
* determines which categories of pages are cached:
|
|
*
|
|
* 0: All clean, inactive pages within the specified physical address range
|
|
* are cached. Will not sleep.
|
|
* 1: The vm_lowmem handlers are called. All inactive pages within
|
|
* the specified physical address range are cached. May sleep.
|
|
* 2: The vm_lowmem handlers are called. All inactive and active pages
|
|
* within the specified physical address range are cached. May sleep.
|
|
*/
|
|
void
|
|
vm_pageout_grow_cache(int tries, vm_paddr_t low, vm_paddr_t high)
|
|
{
|
|
int actl, actmax, inactl, inactmax, dom, initial_dom;
|
|
static int start_dom = 0;
|
|
|
|
if (tries > 0) {
|
|
/*
|
|
* Decrease registered cache sizes. The vm_lowmem handlers
|
|
* may acquire locks and/or sleep, so they can only be invoked
|
|
* when "tries" is greater than zero.
|
|
*/
|
|
EVENTHANDLER_INVOKE(vm_lowmem, 0);
|
|
|
|
/*
|
|
* We do this explicitly after the caches have been drained
|
|
* above.
|
|
*/
|
|
uma_reclaim();
|
|
}
|
|
|
|
/*
|
|
* Make the next scan start on the next domain.
|
|
*/
|
|
initial_dom = atomic_fetchadd_int(&start_dom, 1) % vm_ndomains;
|
|
|
|
inactl = 0;
|
|
inactmax = vm_cnt.v_inactive_count;
|
|
actl = 0;
|
|
actmax = tries < 2 ? 0 : vm_cnt.v_active_count;
|
|
dom = initial_dom;
|
|
|
|
/*
|
|
* Scan domains in round-robin order, first inactive queues,
|
|
* then active. Since domain usually owns large physically
|
|
* contiguous chunk of memory, it makes sense to completely
|
|
* exhaust one domain before switching to next, while growing
|
|
* the pool of contiguous physical pages.
|
|
*
|
|
* Do not even start launder a domain which cannot contain
|
|
* the specified address range, as indicated by segments
|
|
* constituting the domain.
|
|
*/
|
|
again:
|
|
if (inactl < inactmax) {
|
|
if (vm_phys_domain_intersects(vm_dom[dom].vmd_segs,
|
|
low, high) &&
|
|
vm_pageout_launder(&vm_dom[dom].vmd_pagequeues[PQ_INACTIVE],
|
|
tries, low, high)) {
|
|
inactl++;
|
|
goto again;
|
|
}
|
|
if (++dom == vm_ndomains)
|
|
dom = 0;
|
|
if (dom != initial_dom)
|
|
goto again;
|
|
}
|
|
if (actl < actmax) {
|
|
if (vm_phys_domain_intersects(vm_dom[dom].vmd_segs,
|
|
low, high) &&
|
|
vm_pageout_launder(&vm_dom[dom].vmd_pagequeues[PQ_ACTIVE],
|
|
tries, low, high)) {
|
|
actl++;
|
|
goto again;
|
|
}
|
|
if (++dom == vm_ndomains)
|
|
dom = 0;
|
|
if (dom != initial_dom)
|
|
goto again;
|
|
}
|
|
}
|
|
|
|
#if !defined(NO_SWAPPING)
|
|
/*
|
|
* vm_pageout_object_deactivate_pages
|
|
*
|
|
* Deactivate enough pages to satisfy the inactive target
|
|
* requirements.
|
|
*
|
|
* The object and map must be locked.
|
|
*/
|
|
static void
|
|
vm_pageout_object_deactivate_pages(pmap_t pmap, vm_object_t first_object,
|
|
long desired)
|
|
{
|
|
vm_object_t backing_object, object;
|
|
vm_page_t p;
|
|
int act_delta, remove_mode;
|
|
|
|
VM_OBJECT_ASSERT_LOCKED(first_object);
|
|
if ((first_object->flags & OBJ_FICTITIOUS) != 0)
|
|
return;
|
|
for (object = first_object;; object = backing_object) {
|
|
if (pmap_resident_count(pmap) <= desired)
|
|
goto unlock_return;
|
|
VM_OBJECT_ASSERT_LOCKED(object);
|
|
if ((object->flags & OBJ_UNMANAGED) != 0 ||
|
|
object->paging_in_progress != 0)
|
|
goto unlock_return;
|
|
|
|
remove_mode = 0;
|
|
if (object->shadow_count > 1)
|
|
remove_mode = 1;
|
|
/*
|
|
* Scan the object's entire memory queue.
|
|
*/
|
|
TAILQ_FOREACH(p, &object->memq, listq) {
|
|
if (pmap_resident_count(pmap) <= desired)
|
|
goto unlock_return;
|
|
if (vm_page_busied(p))
|
|
continue;
|
|
PCPU_INC(cnt.v_pdpages);
|
|
vm_page_lock(p);
|
|
if (p->wire_count != 0 || p->hold_count != 0 ||
|
|
!pmap_page_exists_quick(pmap, p)) {
|
|
vm_page_unlock(p);
|
|
continue;
|
|
}
|
|
act_delta = pmap_ts_referenced(p);
|
|
if ((p->aflags & PGA_REFERENCED) != 0) {
|
|
if (act_delta == 0)
|
|
act_delta = 1;
|
|
vm_page_aflag_clear(p, PGA_REFERENCED);
|
|
}
|
|
if (p->queue != PQ_ACTIVE && act_delta != 0) {
|
|
vm_page_activate(p);
|
|
p->act_count += act_delta;
|
|
} else if (p->queue == PQ_ACTIVE) {
|
|
if (act_delta == 0) {
|
|
p->act_count -= min(p->act_count,
|
|
ACT_DECLINE);
|
|
if (!remove_mode && p->act_count == 0) {
|
|
pmap_remove_all(p);
|
|
vm_page_deactivate(p);
|
|
} else
|
|
vm_page_requeue(p);
|
|
} else {
|
|
vm_page_activate(p);
|
|
if (p->act_count < ACT_MAX -
|
|
ACT_ADVANCE)
|
|
p->act_count += ACT_ADVANCE;
|
|
vm_page_requeue(p);
|
|
}
|
|
} else if (p->queue == PQ_INACTIVE)
|
|
pmap_remove_all(p);
|
|
vm_page_unlock(p);
|
|
}
|
|
if ((backing_object = object->backing_object) == NULL)
|
|
goto unlock_return;
|
|
VM_OBJECT_RLOCK(backing_object);
|
|
if (object != first_object)
|
|
VM_OBJECT_RUNLOCK(object);
|
|
}
|
|
unlock_return:
|
|
if (object != first_object)
|
|
VM_OBJECT_RUNLOCK(object);
|
|
}
|
|
|
|
/*
|
|
* deactivate some number of pages in a map, try to do it fairly, but
|
|
* that is really hard to do.
|
|
*/
|
|
static void
|
|
vm_pageout_map_deactivate_pages(map, desired)
|
|
vm_map_t map;
|
|
long desired;
|
|
{
|
|
vm_map_entry_t tmpe;
|
|
vm_object_t obj, bigobj;
|
|
int nothingwired;
|
|
|
|
if (!vm_map_trylock(map))
|
|
return;
|
|
|
|
bigobj = NULL;
|
|
nothingwired = TRUE;
|
|
|
|
/*
|
|
* first, search out the biggest object, and try to free pages from
|
|
* that.
|
|
*/
|
|
tmpe = map->header.next;
|
|
while (tmpe != &map->header) {
|
|
if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) {
|
|
obj = tmpe->object.vm_object;
|
|
if (obj != NULL && VM_OBJECT_TRYRLOCK(obj)) {
|
|
if (obj->shadow_count <= 1 &&
|
|
(bigobj == NULL ||
|
|
bigobj->resident_page_count < obj->resident_page_count)) {
|
|
if (bigobj != NULL)
|
|
VM_OBJECT_RUNLOCK(bigobj);
|
|
bigobj = obj;
|
|
} else
|
|
VM_OBJECT_RUNLOCK(obj);
|
|
}
|
|
}
|
|
if (tmpe->wired_count > 0)
|
|
nothingwired = FALSE;
|
|
tmpe = tmpe->next;
|
|
}
|
|
|
|
if (bigobj != NULL) {
|
|
vm_pageout_object_deactivate_pages(map->pmap, bigobj, desired);
|
|
VM_OBJECT_RUNLOCK(bigobj);
|
|
}
|
|
/*
|
|
* Next, hunt around for other pages to deactivate. We actually
|
|
* do this search sort of wrong -- .text first is not the best idea.
|
|
*/
|
|
tmpe = map->header.next;
|
|
while (tmpe != &map->header) {
|
|
if (pmap_resident_count(vm_map_pmap(map)) <= desired)
|
|
break;
|
|
if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) {
|
|
obj = tmpe->object.vm_object;
|
|
if (obj != NULL) {
|
|
VM_OBJECT_RLOCK(obj);
|
|
vm_pageout_object_deactivate_pages(map->pmap, obj, desired);
|
|
VM_OBJECT_RUNLOCK(obj);
|
|
}
|
|
}
|
|
tmpe = tmpe->next;
|
|
}
|
|
|
|
#ifdef __ia64__
|
|
/*
|
|
* Remove all non-wired, managed mappings if a process is swapped out.
|
|
* This will free page table pages.
|
|
*/
|
|
if (desired == 0)
|
|
pmap_remove_pages(map->pmap);
|
|
#else
|
|
/*
|
|
* Remove all mappings if a process is swapped out, this will free page
|
|
* table pages.
|
|
*/
|
|
if (desired == 0 && nothingwired) {
|
|
pmap_remove(vm_map_pmap(map), vm_map_min(map),
|
|
vm_map_max(map));
|
|
}
|
|
#endif
|
|
|
|
vm_map_unlock(map);
|
|
}
|
|
#endif /* !defined(NO_SWAPPING) */
|
|
|
|
/*
|
|
* vm_pageout_scan does the dirty work for the pageout daemon.
|
|
*
|
|
* pass 0 - Update active LRU/deactivate pages
|
|
* pass 1 - Move inactive to cache or free
|
|
* pass 2 - Launder dirty pages
|
|
*/
|
|
static void
|
|
vm_pageout_scan(struct vm_domain *vmd, int pass)
|
|
{
|
|
vm_page_t m, next;
|
|
struct vm_pagequeue *pq;
|
|
vm_object_t object;
|
|
int act_delta, addl_page_shortage, deficit, maxscan, page_shortage;
|
|
int vnodes_skipped = 0;
|
|
int maxlaunder;
|
|
int lockmode;
|
|
boolean_t queues_locked;
|
|
|
|
/*
|
|
* If we need to reclaim memory ask kernel caches to return
|
|
* some. We rate limit to avoid thrashing.
|
|
*/
|
|
if (vmd == &vm_dom[0] && pass > 0 &&
|
|
lowmem_ticks + (lowmem_period * hz) < ticks) {
|
|
/*
|
|
* Decrease registered cache sizes.
|
|
*/
|
|
EVENTHANDLER_INVOKE(vm_lowmem, 0);
|
|
/*
|
|
* We do this explicitly after the caches have been
|
|
* drained above.
|
|
*/
|
|
uma_reclaim();
|
|
lowmem_ticks = ticks;
|
|
}
|
|
|
|
/*
|
|
* The addl_page_shortage is 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;
|
|
|
|
deficit = atomic_readandclear_int(&vm_pageout_deficit);
|
|
|
|
/*
|
|
* Calculate the number of pages we want to either free or move
|
|
* to the cache.
|
|
*/
|
|
page_shortage = vm_paging_target() + deficit;
|
|
|
|
/*
|
|
* maxlaunder limits the number of dirty pages we flush per scan.
|
|
* For most systems a smaller value (16 or 32) is more robust under
|
|
* extreme memory and disk pressure because any unnecessary writes
|
|
* to disk can result in extreme performance degredation. However,
|
|
* systems with excessive dirty pages (especially when MAP_NOSYNC is
|
|
* used) will die horribly with limited laundering. If the pageout
|
|
* daemon cannot clean enough pages in the first pass, we let it go
|
|
* all out in succeeding passes.
|
|
*/
|
|
if ((maxlaunder = vm_max_launder) <= 1)
|
|
maxlaunder = 1;
|
|
if (pass > 1)
|
|
maxlaunder = 10000;
|
|
|
|
/*
|
|
* Start scanning the inactive queue for pages we can move to the
|
|
* cache or free. The scan will stop when the target is reached or
|
|
* we have scanned the entire inactive queue. Note that m->act_count
|
|
* is not used to form decisions for the inactive queue, only for the
|
|
* active queue.
|
|
*/
|
|
pq = &vmd->vmd_pagequeues[PQ_INACTIVE];
|
|
maxscan = pq->pq_cnt;
|
|
vm_pagequeue_lock(pq);
|
|
queues_locked = TRUE;
|
|
for (m = TAILQ_FIRST(&pq->pq_pl);
|
|
m != NULL && maxscan-- > 0 && page_shortage > 0;
|
|
m = next) {
|
|
vm_pagequeue_assert_locked(pq);
|
|
KASSERT(queues_locked, ("unlocked queues"));
|
|
KASSERT(m->queue == PQ_INACTIVE, ("Inactive queue %p", m));
|
|
|
|
PCPU_INC(cnt.v_pdpages);
|
|
next = TAILQ_NEXT(m, plinks.q);
|
|
|
|
/*
|
|
* skip marker pages
|
|
*/
|
|
if (m->flags & PG_MARKER)
|
|
continue;
|
|
|
|
KASSERT((m->flags & PG_FICTITIOUS) == 0,
|
|
("Fictitious page %p cannot be in inactive queue", m));
|
|
KASSERT((m->oflags & VPO_UNMANAGED) == 0,
|
|
("Unmanaged page %p cannot be in inactive queue", m));
|
|
|
|
/*
|
|
* The page or object lock acquisitions fail if the
|
|
* page was removed from the queue or moved to a
|
|
* different position within the queue. In either
|
|
* case, addl_page_shortage should not be incremented.
|
|
*/
|
|
if (!vm_pageout_page_lock(m, &next)) {
|
|
vm_page_unlock(m);
|
|
continue;
|
|
}
|
|
object = m->object;
|
|
if (!VM_OBJECT_TRYWLOCK(object) &&
|
|
!vm_pageout_fallback_object_lock(m, &next)) {
|
|
vm_page_unlock(m);
|
|
VM_OBJECT_WUNLOCK(object);
|
|
continue;
|
|
}
|
|
|
|
/*
|
|
* Don't mess with busy pages, keep them at at the
|
|
* front of the queue, most likely they are being
|
|
* paged out. Increment addl_page_shortage for busy
|
|
* pages, because they may leave the inactive queue
|
|
* shortly after page scan is finished.
|
|
*/
|
|
if (vm_page_busied(m)) {
|
|
vm_page_unlock(m);
|
|
VM_OBJECT_WUNLOCK(object);
|
|
addl_page_shortage++;
|
|
continue;
|
|
}
|
|
|
|
/*
|
|
* We unlock the inactive page queue, invalidating the
|
|
* 'next' pointer. Use our marker to remember our
|
|
* place.
|
|
*/
|
|
TAILQ_INSERT_AFTER(&pq->pq_pl, m, &vmd->vmd_marker, plinks.q);
|
|
vm_pagequeue_unlock(pq);
|
|
queues_locked = FALSE;
|
|
|
|
/*
|
|
* We bump the activation count if the page has been
|
|
* referenced while in the inactive queue. This makes
|
|
* it less likely that the page will be added back to the
|
|
* inactive queue prematurely again. Here we check the
|
|
* page tables (or emulated bits, if any), given the upper
|
|
* level VM system not knowing anything about existing
|
|
* references.
|
|
*/
|
|
if ((m->aflags & PGA_REFERENCED) != 0) {
|
|
vm_page_aflag_clear(m, PGA_REFERENCED);
|
|
act_delta = 1;
|
|
} else
|
|
act_delta = 0;
|
|
if (object->ref_count != 0) {
|
|
act_delta += pmap_ts_referenced(m);
|
|
} else {
|
|
KASSERT(!pmap_page_is_mapped(m),
|
|
("vm_pageout_scan: page %p is mapped", m));
|
|
}
|
|
|
|
/*
|
|
* If the upper level VM system knows about any page
|
|
* references, we reactivate the page or requeue it.
|
|
*/
|
|
if (act_delta != 0) {
|
|
if (object->ref_count != 0) {
|
|
vm_page_activate(m);
|
|
m->act_count += act_delta + ACT_ADVANCE;
|
|
} else {
|
|
vm_pagequeue_lock(pq);
|
|
queues_locked = TRUE;
|
|
vm_page_requeue_locked(m);
|
|
}
|
|
VM_OBJECT_WUNLOCK(object);
|
|
vm_page_unlock(m);
|
|
goto relock_queues;
|
|
}
|
|
|
|
if (m->hold_count != 0) {
|
|
vm_page_unlock(m);
|
|
VM_OBJECT_WUNLOCK(object);
|
|
|
|
/*
|
|
* Held pages are essentially stuck in the
|
|
* queue. So, they ought to be discounted
|
|
* from the inactive count. See the
|
|
* calculation of the page_shortage for the
|
|
* loop over the active queue below.
|
|
*/
|
|
addl_page_shortage++;
|
|
goto relock_queues;
|
|
}
|
|
|
|
/*
|
|
* If the page appears to be clean at the machine-independent
|
|
* layer, then remove all of its mappings from the pmap in
|
|
* anticipation of placing it onto the cache queue. 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.
|
|
*/
|
|
vm_page_test_dirty(m);
|
|
if (m->dirty == 0 && object->ref_count != 0)
|
|
pmap_remove_all(m);
|
|
|
|
if (m->valid == 0) {
|
|
/*
|
|
* Invalid pages can be easily freed
|
|
*/
|
|
vm_page_free(m);
|
|
PCPU_INC(cnt.v_dfree);
|
|
--page_shortage;
|
|
} else if (m->dirty == 0) {
|
|
/*
|
|
* Clean pages can be placed onto the cache queue.
|
|
* This effectively frees them.
|
|
*/
|
|
vm_page_cache(m);
|
|
--page_shortage;
|
|
} else if ((m->flags & PG_WINATCFLS) == 0 && pass < 2) {
|
|
/*
|
|
* Dirty pages need to be paged out, but flushing
|
|
* a page is extremely expensive versus freeing
|
|
* a clean page. Rather then artificially limiting
|
|
* the number of pages we can flush, we instead give
|
|
* dirty pages extra priority on the inactive queue
|
|
* by forcing them to be cycled through the queue
|
|
* twice before being flushed, after which the
|
|
* (now clean) page will cycle through once more
|
|
* before being freed. This significantly extends
|
|
* the thrash point for a heavily loaded machine.
|
|
*/
|
|
m->flags |= PG_WINATCFLS;
|
|
vm_pagequeue_lock(pq);
|
|
queues_locked = TRUE;
|
|
vm_page_requeue_locked(m);
|
|
} else if (maxlaunder > 0) {
|
|
/*
|
|
* We always want to try to flush some dirty pages if
|
|
* we encounter them, to keep the system stable.
|
|
* Normally this number is small, but under extreme
|
|
* pressure where there are insufficient clean pages
|
|
* on the inactive queue, we may have to go all out.
|
|
*/
|
|
int swap_pageouts_ok;
|
|
struct vnode *vp = NULL;
|
|
struct mount *mp = NULL;
|
|
|
|
if ((object->type != OBJT_SWAP) && (object->type != OBJT_DEFAULT)) {
|
|
swap_pageouts_ok = 1;
|
|
} else {
|
|
swap_pageouts_ok = !(defer_swap_pageouts || disable_swap_pageouts);
|
|
swap_pageouts_ok |= (!disable_swap_pageouts && defer_swap_pageouts &&
|
|
vm_page_count_min());
|
|
|
|
}
|
|
|
|
/*
|
|
* We don't bother paging objects that are "dead".
|
|
* Those objects are in a "rundown" state.
|
|
*/
|
|
if (!swap_pageouts_ok || (object->flags & OBJ_DEAD)) {
|
|
vm_pagequeue_lock(pq);
|
|
vm_page_unlock(m);
|
|
VM_OBJECT_WUNLOCK(object);
|
|
queues_locked = TRUE;
|
|
vm_page_requeue_locked(m);
|
|
goto relock_queues;
|
|
}
|
|
|
|
/*
|
|
* 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.
|
|
*
|
|
* The previous code skipped locked vnodes and, worse,
|
|
* reordered pages in the queue. This results in
|
|
* completely non-deterministic operation and, on a
|
|
* busy system, can lead to extremely non-optimal
|
|
* pageouts. For example, it can cause clean pages
|
|
* to be freed and dirty pages to be moved to the end
|
|
* of the queue. Since dirty pages are also moved to
|
|
* the end of the queue once-cleaned, this gives
|
|
* way too large a weighting to deferring the freeing
|
|
* of dirty pages.
|
|
*
|
|
* 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_unlock(m);
|
|
vp = object->handle;
|
|
if (vp->v_type == VREG &&
|
|
vn_start_write(vp, &mp, V_NOWAIT) != 0) {
|
|
mp = NULL;
|
|
++pageout_lock_miss;
|
|
if (object->flags & OBJ_MIGHTBEDIRTY)
|
|
vnodes_skipped++;
|
|
goto unlock_and_continue;
|
|
}
|
|
KASSERT(mp != NULL,
|
|
("vp %p with NULL v_mount", vp));
|
|
vm_object_reference_locked(object);
|
|
VM_OBJECT_WUNLOCK(object);
|
|
lockmode = MNT_SHARED_WRITES(vp->v_mount) ?
|
|
LK_SHARED : LK_EXCLUSIVE;
|
|
if (vget(vp, lockmode | LK_TIMELOCK,
|
|
curthread)) {
|
|
VM_OBJECT_WLOCK(object);
|
|
++pageout_lock_miss;
|
|
if (object->flags & OBJ_MIGHTBEDIRTY)
|
|
vnodes_skipped++;
|
|
vp = NULL;
|
|
goto unlock_and_continue;
|
|
}
|
|
VM_OBJECT_WLOCK(object);
|
|
vm_page_lock(m);
|
|
vm_pagequeue_lock(pq);
|
|
queues_locked = TRUE;
|
|
/*
|
|
* The page might have been moved to another
|
|
* queue during potential blocking in vget()
|
|
* above. The page might have been freed and
|
|
* reused for another vnode.
|
|
*/
|
|
if (m->queue != PQ_INACTIVE ||
|
|
m->object != object ||
|
|
TAILQ_NEXT(m, plinks.q) != &vmd->vmd_marker) {
|
|
vm_page_unlock(m);
|
|
if (object->flags & OBJ_MIGHTBEDIRTY)
|
|
vnodes_skipped++;
|
|
goto unlock_and_continue;
|
|
}
|
|
|
|
/*
|
|
* The page may have been busied during the
|
|
* blocking in vget(). We don't move the
|
|
* page back onto the end of the queue so that
|
|
* statistics are more correct if we don't.
|
|
*/
|
|
if (vm_page_busied(m)) {
|
|
vm_page_unlock(m);
|
|
addl_page_shortage++;
|
|
goto unlock_and_continue;
|
|
}
|
|
|
|
/*
|
|
* If the page has become held it might
|
|
* be undergoing I/O, so skip it
|
|
*/
|
|
if (m->hold_count != 0) {
|
|
vm_page_unlock(m);
|
|
addl_page_shortage++;
|
|
if (object->flags & OBJ_MIGHTBEDIRTY)
|
|
vnodes_skipped++;
|
|
goto unlock_and_continue;
|
|
}
|
|
vm_pagequeue_unlock(pq);
|
|
queues_locked = FALSE;
|
|
}
|
|
|
|
/*
|
|
* 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.
|
|
*
|
|
* decrement page_shortage on success to account for
|
|
* the (future) cleaned page. Otherwise we could wind
|
|
* up laundering or cleaning too many pages.
|
|
*/
|
|
if (vm_pageout_clean(m) != 0) {
|
|
--page_shortage;
|
|
--maxlaunder;
|
|
}
|
|
unlock_and_continue:
|
|
vm_page_lock_assert(m, MA_NOTOWNED);
|
|
VM_OBJECT_WUNLOCK(object);
|
|
if (mp != NULL) {
|
|
if (queues_locked) {
|
|
vm_pagequeue_unlock(pq);
|
|
queues_locked = FALSE;
|
|
}
|
|
if (vp != NULL)
|
|
vput(vp);
|
|
vm_object_deallocate(object);
|
|
vn_finished_write(mp);
|
|
}
|
|
vm_page_lock_assert(m, MA_NOTOWNED);
|
|
goto relock_queues;
|
|
}
|
|
vm_page_unlock(m);
|
|
VM_OBJECT_WUNLOCK(object);
|
|
relock_queues:
|
|
if (!queues_locked) {
|
|
vm_pagequeue_lock(pq);
|
|
queues_locked = TRUE;
|
|
}
|
|
next = TAILQ_NEXT(&vmd->vmd_marker, plinks.q);
|
|
TAILQ_REMOVE(&pq->pq_pl, &vmd->vmd_marker, plinks.q);
|
|
}
|
|
vm_pagequeue_unlock(pq);
|
|
|
|
/*
|
|
* Compute the number of pages we want to try to move from the
|
|
* active queue to the inactive queue.
|
|
*/
|
|
page_shortage = vm_cnt.v_inactive_target - vm_cnt.v_inactive_count +
|
|
vm_paging_target() + deficit + addl_page_shortage;
|
|
|
|
pq = &vmd->vmd_pagequeues[PQ_ACTIVE];
|
|
vm_pagequeue_lock(pq);
|
|
maxscan = pq->pq_cnt;
|
|
|
|
/*
|
|
* If we're just idle polling attempt to visit every
|
|
* active page within 'update_period' seconds.
|
|
*/
|
|
if (pass == 0 && vm_pageout_update_period != 0) {
|
|
maxscan /= vm_pageout_update_period;
|
|
page_shortage = maxscan;
|
|
}
|
|
|
|
/*
|
|
* Scan the active queue for things we can deactivate. We nominally
|
|
* track the per-page activity counter and use it to locate
|
|
* deactivation candidates.
|
|
*/
|
|
m = TAILQ_FIRST(&pq->pq_pl);
|
|
while (m != NULL && maxscan-- > 0 && page_shortage > 0) {
|
|
|
|
KASSERT(m->queue == PQ_ACTIVE,
|
|
("vm_pageout_scan: page %p isn't active", m));
|
|
|
|
next = TAILQ_NEXT(m, plinks.q);
|
|
if ((m->flags & PG_MARKER) != 0) {
|
|
m = next;
|
|
continue;
|
|
}
|
|
KASSERT((m->flags & PG_FICTITIOUS) == 0,
|
|
("Fictitious page %p cannot be in active queue", m));
|
|
KASSERT((m->oflags & VPO_UNMANAGED) == 0,
|
|
("Unmanaged page %p cannot be in active queue", m));
|
|
if (!vm_pageout_page_lock(m, &next)) {
|
|
vm_page_unlock(m);
|
|
m = next;
|
|
continue;
|
|
}
|
|
|
|
/*
|
|
* The count for pagedaemon pages is done after checking the
|
|
* page for eligibility...
|
|
*/
|
|
PCPU_INC(cnt.v_pdpages);
|
|
|
|
/*
|
|
* Check to see "how much" the page has been used.
|
|
*/
|
|
if ((m->aflags & PGA_REFERENCED) != 0) {
|
|
vm_page_aflag_clear(m, PGA_REFERENCED);
|
|
act_delta = 1;
|
|
} else
|
|
act_delta = 0;
|
|
|
|
/*
|
|
* Unlocked object ref count check. Two races are possible.
|
|
* 1) The ref was transitioning to zero and we saw non-zero,
|
|
* the pmap bits will be checked unnecessarily.
|
|
* 2) The ref was transitioning to one and we saw zero.
|
|
* The page lock prevents a new reference to this page so
|
|
* we need not check the reference bits.
|
|
*/
|
|
if (m->object->ref_count != 0)
|
|
act_delta += pmap_ts_referenced(m);
|
|
|
|
/*
|
|
* Advance or decay the act_count based on recent usage.
|
|
*/
|
|
if (act_delta != 0) {
|
|
m->act_count += ACT_ADVANCE + act_delta;
|
|
if (m->act_count > ACT_MAX)
|
|
m->act_count = ACT_MAX;
|
|
} else
|
|
m->act_count -= min(m->act_count, ACT_DECLINE);
|
|
|
|
/*
|
|
* Move this page to the tail of the active or inactive
|
|
* queue depending on usage.
|
|
*/
|
|
if (m->act_count == 0) {
|
|
/* Dequeue to avoid later lock recursion. */
|
|
vm_page_dequeue_locked(m);
|
|
vm_page_deactivate(m);
|
|
page_shortage--;
|
|
} else
|
|
vm_page_requeue_locked(m);
|
|
vm_page_unlock(m);
|
|
m = next;
|
|
}
|
|
vm_pagequeue_unlock(pq);
|
|
#if !defined(NO_SWAPPING)
|
|
/*
|
|
* Idle process swapout -- run once per second.
|
|
*/
|
|
if (vm_swap_idle_enabled) {
|
|
static long lsec;
|
|
if (time_second != lsec) {
|
|
vm_req_vmdaemon(VM_SWAP_IDLE);
|
|
lsec = time_second;
|
|
}
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* If we didn't get enough free pages, and we have skipped a vnode
|
|
* in a writeable object, wakeup the sync daemon. And kick swapout
|
|
* if we did not get enough free pages.
|
|
*/
|
|
if (vm_paging_target() > 0) {
|
|
if (vnodes_skipped && vm_page_count_min())
|
|
(void) speedup_syncer();
|
|
#if !defined(NO_SWAPPING)
|
|
if (vm_swap_enabled && vm_page_count_target())
|
|
vm_req_vmdaemon(VM_SWAP_NORMAL);
|
|
#endif
|
|
}
|
|
|
|
/*
|
|
* If we are critically low on one of RAM or swap and low on
|
|
* the other, kill the largest process. However, we avoid
|
|
* doing this on the first pass in order to give ourselves a
|
|
* chance to flush out dirty vnode-backed pages and to allow
|
|
* active pages to be moved to the inactive queue and reclaimed.
|
|
*/
|
|
vm_pageout_mightbe_oom(vmd, pass);
|
|
}
|
|
|
|
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 pass)
|
|
{
|
|
int old_vote;
|
|
|
|
if (pass <= 1 || !((swap_pager_avail < 64 && vm_page_count_min()) ||
|
|
(swap_pager_full && vm_paging_target() > 0))) {
|
|
if (vmd->vmd_oom) {
|
|
vmd->vmd_oom = FALSE;
|
|
atomic_subtract_int(&vm_pageout_oom_vote, 1);
|
|
}
|
|
return;
|
|
}
|
|
|
|
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);
|
|
}
|
|
|
|
void
|
|
vm_pageout_oom(int shortage)
|
|
{
|
|
struct proc *p, *bigproc;
|
|
vm_offset_t size, bigsize;
|
|
struct thread *td;
|
|
struct vmspace *vm;
|
|
|
|
/*
|
|
* 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 it's 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) {
|
|
int breakout;
|
|
|
|
if (PROC_TRYLOCK(p) == 0)
|
|
continue;
|
|
/*
|
|
* 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->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 = 0;
|
|
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)) {
|
|
thread_unlock(td);
|
|
breakout = 1;
|
|
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;
|
|
}
|
|
if (!vm_map_trylock_read(&vm->vm_map)) {
|
|
vmspace_free(vm);
|
|
PROC_UNLOCK(p);
|
|
continue;
|
|
}
|
|
size = vmspace_swap_count(vm);
|
|
vm_map_unlock_read(&vm->vm_map);
|
|
if (shortage == VM_OOM_MEM)
|
|
size += vmspace_resident_count(vm);
|
|
vmspace_free(vm);
|
|
/*
|
|
* if the this process is bigger than the biggest one
|
|
* remember it.
|
|
*/
|
|
if (size > bigsize) {
|
|
if (bigproc != NULL)
|
|
PROC_UNLOCK(bigproc);
|
|
bigproc = p;
|
|
bigsize = size;
|
|
} else
|
|
PROC_UNLOCK(p);
|
|
}
|
|
sx_sunlock(&allproc_lock);
|
|
if (bigproc != NULL) {
|
|
killproc(bigproc, "out of swap space");
|
|
sched_nice(bigproc, PRIO_MIN);
|
|
PROC_UNLOCK(bigproc);
|
|
wakeup(&vm_cnt.v_free_count);
|
|
}
|
|
}
|
|
|
|
static void
|
|
vm_pageout_worker(void *arg)
|
|
{
|
|
struct vm_domain *domain;
|
|
int domidx;
|
|
|
|
domidx = (uintptr_t)arg;
|
|
domain = &vm_dom[domidx];
|
|
|
|
/*
|
|
* 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(domain->vmd_segs != 0, ("domain without segments"));
|
|
vm_pageout_init_marker(&domain->vmd_marker, PQ_INACTIVE);
|
|
|
|
/*
|
|
* The pageout daemon worker is never done, so loop forever.
|
|
*/
|
|
while (TRUE) {
|
|
/*
|
|
* If we have enough free memory, wakeup waiters. Do
|
|
* not clear vm_pages_needed until we reach our target,
|
|
* otherwise we may be woken up over and over again and
|
|
* waste a lot of cpu.
|
|
*/
|
|
mtx_lock(&vm_page_queue_free_mtx);
|
|
if (vm_pages_needed && !vm_page_count_min()) {
|
|
if (!vm_paging_needed())
|
|
vm_pages_needed = 0;
|
|
wakeup(&vm_cnt.v_free_count);
|
|
}
|
|
if (vm_pages_needed) {
|
|
/*
|
|
* Still not done, take a second pass without waiting
|
|
* (unlimited dirty cleaning), otherwise sleep a bit
|
|
* and try again.
|
|
*/
|
|
if (domain->vmd_pass > 1)
|
|
msleep(&vm_pages_needed,
|
|
&vm_page_queue_free_mtx, PVM, "psleep",
|
|
hz / 2);
|
|
} else {
|
|
/*
|
|
* Good enough, sleep until required to refresh
|
|
* stats.
|
|
*/
|
|
domain->vmd_pass = 0;
|
|
msleep(&vm_pages_needed, &vm_page_queue_free_mtx,
|
|
PVM, "psleep", hz);
|
|
|
|
}
|
|
if (vm_pages_needed) {
|
|
vm_cnt.v_pdwakeups++;
|
|
domain->vmd_pass++;
|
|
}
|
|
mtx_unlock(&vm_page_queue_free_mtx);
|
|
vm_pageout_scan(domain, domain->vmd_pass);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* vm_pageout is the high level pageout daemon.
|
|
*/
|
|
static void
|
|
vm_pageout(void)
|
|
{
|
|
#if MAXMEMDOM > 1
|
|
int error, i;
|
|
#endif
|
|
|
|
/*
|
|
* Initialize some paging parameters.
|
|
*/
|
|
vm_cnt.v_interrupt_free_min = 2;
|
|
if (vm_cnt.v_page_count < 2000)
|
|
vm_pageout_page_count = 8;
|
|
|
|
/*
|
|
* v_free_reserved needs to include enough for the largest
|
|
* swap pager structures plus enough for any pv_entry structs
|
|
* when paging.
|
|
*/
|
|
if (vm_cnt.v_page_count > 1024)
|
|
vm_cnt.v_free_min = 4 + (vm_cnt.v_page_count - 1024) / 200;
|
|
else
|
|
vm_cnt.v_free_min = 4;
|
|
vm_cnt.v_pageout_free_min = (2*MAXBSIZE)/PAGE_SIZE +
|
|
vm_cnt.v_interrupt_free_min;
|
|
vm_cnt.v_free_reserved = vm_pageout_page_count +
|
|
vm_cnt.v_pageout_free_min + (vm_cnt.v_page_count / 768);
|
|
vm_cnt.v_free_severe = vm_cnt.v_free_min / 2;
|
|
vm_cnt.v_free_target = 4 * vm_cnt.v_free_min + vm_cnt.v_free_reserved;
|
|
vm_cnt.v_free_min += vm_cnt.v_free_reserved;
|
|
vm_cnt.v_free_severe += vm_cnt.v_free_reserved;
|
|
vm_cnt.v_inactive_target = (3 * vm_cnt.v_free_target) / 2;
|
|
if (vm_cnt.v_inactive_target > vm_cnt.v_free_count / 3)
|
|
vm_cnt.v_inactive_target = vm_cnt.v_free_count / 3;
|
|
|
|
/*
|
|
* Set the default wakeup threshold to be 10% above the minimum
|
|
* page limit. This keeps the steady state out of shortfall.
|
|
*/
|
|
vm_pageout_wakeup_thresh = (vm_cnt.v_free_min / 10) * 11;
|
|
|
|
/*
|
|
* 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;
|
|
|
|
/* XXX does not really belong here */
|
|
if (vm_page_max_wired == 0)
|
|
vm_page_max_wired = vm_cnt.v_free_count / 3;
|
|
|
|
swap_pager_swap_init();
|
|
#if MAXMEMDOM > 1
|
|
for (i = 1; i < vm_ndomains; i++) {
|
|
error = kthread_add(vm_pageout_worker, (void *)(uintptr_t)i,
|
|
curproc, NULL, 0, 0, "dom%d", i);
|
|
if (error != 0) {
|
|
panic("starting pageout for domain %d, error %d\n",
|
|
i, error);
|
|
}
|
|
}
|
|
#endif
|
|
vm_pageout_worker((void *)(uintptr_t)0);
|
|
}
|
|
|
|
/*
|
|
* Unless the free page queue lock is held by the caller, this function
|
|
* should be regarded as advisory. Specifically, the caller should
|
|
* not msleep() on &vm_cnt.v_free_count following this function unless
|
|
* the free page queue lock is held until the msleep() is performed.
|
|
*/
|
|
void
|
|
pagedaemon_wakeup(void)
|
|
{
|
|
|
|
if (!vm_pages_needed && curthread->td_proc != pageproc) {
|
|
vm_pages_needed = 1;
|
|
wakeup(&vm_pages_needed);
|
|
}
|
|
}
|
|
|
|
#if !defined(NO_SWAPPING)
|
|
static void
|
|
vm_req_vmdaemon(int req)
|
|
{
|
|
static int lastrun = 0;
|
|
|
|
mtx_lock(&vm_daemon_mtx);
|
|
vm_pageout_req_swapout |= req;
|
|
if ((ticks > (lastrun + hz)) || (ticks < lastrun)) {
|
|
wakeup(&vm_daemon_needed);
|
|
lastrun = ticks;
|
|
}
|
|
mtx_unlock(&vm_daemon_mtx);
|
|
}
|
|
|
|
static void
|
|
vm_daemon(void)
|
|
{
|
|
struct rlimit rsslim;
|
|
struct proc *p;
|
|
struct thread *td;
|
|
struct vmspace *vm;
|
|
int breakout, swapout_flags, tryagain, attempts;
|
|
#ifdef RACCT
|
|
uint64_t rsize, ravailable;
|
|
#endif
|
|
|
|
while (TRUE) {
|
|
mtx_lock(&vm_daemon_mtx);
|
|
#ifdef RACCT
|
|
msleep(&vm_daemon_needed, &vm_daemon_mtx, PPAUSE, "psleep", hz);
|
|
#else
|
|
msleep(&vm_daemon_needed, &vm_daemon_mtx, PPAUSE, "psleep", 0);
|
|
#endif
|
|
swapout_flags = vm_pageout_req_swapout;
|
|
vm_pageout_req_swapout = 0;
|
|
mtx_unlock(&vm_daemon_mtx);
|
|
if (swapout_flags)
|
|
swapout_procs(swapout_flags);
|
|
|
|
/*
|
|
* scan the processes for exceeding their rlimits or if
|
|
* process is swapped out -- deactivate pages
|
|
*/
|
|
tryagain = 0;
|
|
attempts = 0;
|
|
again:
|
|
attempts++;
|
|
sx_slock(&allproc_lock);
|
|
FOREACH_PROC_IN_SYSTEM(p) {
|
|
vm_pindex_t limit, size;
|
|
|
|
/*
|
|
* if this is a system process or if we have already
|
|
* looked at this process, skip it.
|
|
*/
|
|
PROC_LOCK(p);
|
|
if (p->p_state != PRS_NORMAL ||
|
|
p->p_flag & (P_INEXEC | P_SYSTEM | P_WEXIT)) {
|
|
PROC_UNLOCK(p);
|
|
continue;
|
|
}
|
|
/*
|
|
* if the process is in a non-running type state,
|
|
* don't touch it.
|
|
*/
|
|
breakout = 0;
|
|
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)) {
|
|
thread_unlock(td);
|
|
breakout = 1;
|
|
break;
|
|
}
|
|
thread_unlock(td);
|
|
}
|
|
if (breakout) {
|
|
PROC_UNLOCK(p);
|
|
continue;
|
|
}
|
|
/*
|
|
* get a limit
|
|
*/
|
|
lim_rlimit(p, RLIMIT_RSS, &rsslim);
|
|
limit = OFF_TO_IDX(
|
|
qmin(rsslim.rlim_cur, rsslim.rlim_max));
|
|
|
|
/*
|
|
* let processes that are swapped out really be
|
|
* swapped out set the limit to nothing (will force a
|
|
* swap-out.)
|
|
*/
|
|
if ((p->p_flag & P_INMEM) == 0)
|
|
limit = 0; /* XXX */
|
|
vm = vmspace_acquire_ref(p);
|
|
PROC_UNLOCK(p);
|
|
if (vm == NULL)
|
|
continue;
|
|
|
|
size = vmspace_resident_count(vm);
|
|
if (size >= limit) {
|
|
vm_pageout_map_deactivate_pages(
|
|
&vm->vm_map, limit);
|
|
}
|
|
#ifdef RACCT
|
|
rsize = IDX_TO_OFF(size);
|
|
PROC_LOCK(p);
|
|
racct_set(p, RACCT_RSS, rsize);
|
|
ravailable = racct_get_available(p, RACCT_RSS);
|
|
PROC_UNLOCK(p);
|
|
if (rsize > ravailable) {
|
|
/*
|
|
* Don't be overly aggressive; this might be
|
|
* an innocent process, and the limit could've
|
|
* been exceeded by some memory hog. Don't
|
|
* try to deactivate more than 1/4th of process'
|
|
* resident set size.
|
|
*/
|
|
if (attempts <= 8) {
|
|
if (ravailable < rsize - (rsize / 4))
|
|
ravailable = rsize - (rsize / 4);
|
|
}
|
|
vm_pageout_map_deactivate_pages(
|
|
&vm->vm_map, OFF_TO_IDX(ravailable));
|
|
/* Update RSS usage after paging out. */
|
|
size = vmspace_resident_count(vm);
|
|
rsize = IDX_TO_OFF(size);
|
|
PROC_LOCK(p);
|
|
racct_set(p, RACCT_RSS, rsize);
|
|
PROC_UNLOCK(p);
|
|
if (rsize > ravailable)
|
|
tryagain = 1;
|
|
}
|
|
#endif
|
|
vmspace_free(vm);
|
|
}
|
|
sx_sunlock(&allproc_lock);
|
|
if (tryagain != 0 && attempts <= 10)
|
|
goto again;
|
|
}
|
|
}
|
|
#endif /* !defined(NO_SWAPPING) */
|