9f5632e6c8
With the previous reviews, the page lock is no longer required in order to perform queue operations on a page. It is also no longer needed in the page queue scans. This change effectively eliminates remaining uses of the page lock and also the false sharing caused by multiple pages sharing a page lock. Reviewed by: jeff Tested by: pho Sponsored by: Netflix, Intel Differential Revision: https://reviews.freebsd.org/D22885
948 lines
24 KiB
C
948 lines
24 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
|
|
* documentation and/or other materials provided with the distribution.
|
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* 3. All advertising materials mentioning features or use of this software
|
|
* 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
|
|
* 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
|
|
* 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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*
|
|
* from: @(#)vm_pageout.c 7.4 (Berkeley) 5/7/91
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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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|
* Permission to use, copy, modify and distribute this software and
|
|
* its documentation is hereby granted, provided that both the copyright
|
|
* notice and this permission notice appear in all copies of the
|
|
* software, derivative works or modified versions, and any portions
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|
* thereof, and that both notices appear in supporting documentation.
|
|
*
|
|
* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
|
|
* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
|
|
* 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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|
* 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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|
*
|
|
* any improvements or extensions that they make and grant Carnegie the
|
|
* rights to redistribute these changes.
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|
*/
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|
|
|
#include <sys/cdefs.h>
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|
__FBSDID("$FreeBSD$");
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|
|
|
#include "opt_kstack_pages.h"
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|
#include "opt_kstack_max_pages.h"
|
|
#include "opt_vm.h"
|
|
|
|
#include <sys/param.h>
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|
#include <sys/systm.h>
|
|
#include <sys/limits.h>
|
|
#include <sys/kernel.h>
|
|
#include <sys/eventhandler.h>
|
|
#include <sys/lock.h>
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|
#include <sys/mutex.h>
|
|
#include <sys/proc.h>
|
|
#include <sys/kthread.h>
|
|
#include <sys/ktr.h>
|
|
#include <sys/mount.h>
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|
#include <sys/racct.h>
|
|
#include <sys/resourcevar.h>
|
|
#include <sys/refcount.h>
|
|
#include <sys/sched.h>
|
|
#include <sys/sdt.h>
|
|
#include <sys/signalvar.h>
|
|
#include <sys/smp.h>
|
|
#include <sys/time.h>
|
|
#include <sys/vnode.h>
|
|
#include <sys/vmmeter.h>
|
|
#include <sys/rwlock.h>
|
|
#include <sys/sx.h>
|
|
#include <sys/sysctl.h>
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|
|
|
#include <vm/vm.h>
|
|
#include <vm/vm_param.h>
|
|
#include <vm/vm_object.h>
|
|
#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>
|
|
#include <vm/swap_pager.h>
|
|
#include <vm/vm_extern.h>
|
|
#include <vm/uma.h>
|
|
|
|
/* 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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};
|
|
SYSINIT(vmdaemon, SI_SUB_KTHREAD_VM, SI_ORDER_FIRST, kproc_start, &vm_kp);
|
|
|
|
static int vm_swap_enabled = 1;
|
|
static int vm_swap_idle_enabled = 0;
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|
|
|
SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled, CTLFLAG_RW,
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&vm_swap_enabled, 0,
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"Enable entire process swapout");
|
|
SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled, CTLFLAG_RW,
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&vm_swap_idle_enabled, 0,
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|
"Allow swapout on idle criteria");
|
|
|
|
/*
|
|
* Swap_idle_threshold1 is the guaranteed swapped in time for a process
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|
*/
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|
static int swap_idle_threshold1 = 2;
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SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold1, CTLFLAG_RW,
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&swap_idle_threshold1, 0,
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"Guaranteed swapped in time for a process");
|
|
|
|
/*
|
|
* Swap_idle_threshold2 is the time that a process can be idle before
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* it will be swapped out, if idle swapping is enabled.
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|
*/
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|
static int swap_idle_threshold2 = 10;
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SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold2, CTLFLAG_RW,
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&swap_idle_threshold2, 0,
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"Time before a process will be swapped out");
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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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|
|
|
static int swapped_cnt;
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|
static int swap_inprogress; /* Pending swap-ins done outside swapper. */
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static int last_swapin;
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|
|
|
static void swapclear(struct proc *);
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|
static int swapout(struct proc *);
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|
static void vm_swapout_map_deactivate_pages(vm_map_t, long);
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|
static void vm_swapout_object_deactivate(pmap_t, vm_object_t, long);
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static void swapout_procs(int action);
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|
static void vm_req_vmdaemon(int req);
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static void vm_thread_swapout(struct thread *td);
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|
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|
static void
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|
vm_swapout_object_deactivate_page(pmap_t pmap, vm_page_t m, bool unmap)
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|
{
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|
|
|
/*
|
|
* Ignore unreclaimable wired pages. Repeat the check after busying
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* since a busy holder may wire the page.
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|
*/
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|
if (vm_page_wired(m) || !vm_page_tryxbusy(m))
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return;
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|
|
|
if (vm_page_wired(m) || !pmap_page_exists_quick(pmap, m)) {
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|
vm_page_xunbusy(m);
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|
return;
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}
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|
if (!pmap_is_referenced(m)) {
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if (!vm_page_active(m))
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(void)vm_page_try_remove_all(m);
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else if (unmap && vm_page_try_remove_all(m))
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vm_page_deactivate(m);
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}
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vm_page_xunbusy(m);
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}
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|
|
/*
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* vm_swapout_object_deactivate
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*
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* Deactivate enough pages to satisfy the inactive target
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* requirements.
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*
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* The object and map must be locked.
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*/
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static void
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vm_swapout_object_deactivate(pmap_t pmap, vm_object_t first_object,
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long desired)
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{
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vm_object_t backing_object, object;
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vm_page_t m;
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bool unmap;
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VM_OBJECT_ASSERT_LOCKED(first_object);
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if ((first_object->flags & OBJ_FICTITIOUS) != 0)
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return;
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for (object = first_object;; object = backing_object) {
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if (pmap_resident_count(pmap) <= desired)
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goto unlock_return;
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VM_OBJECT_ASSERT_LOCKED(object);
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if ((object->flags & OBJ_UNMANAGED) != 0 ||
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REFCOUNT_COUNT(object->paging_in_progress) > 0)
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goto unlock_return;
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unmap = true;
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if (object->shadow_count > 1)
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unmap = false;
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/*
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* Scan the object's entire memory queue.
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*/
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TAILQ_FOREACH(m, &object->memq, listq) {
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if (pmap_resident_count(pmap) <= desired)
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goto unlock_return;
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if (should_yield())
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goto unlock_return;
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vm_swapout_object_deactivate_page(pmap, m, unmap);
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}
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if ((backing_object = object->backing_object) == NULL)
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goto unlock_return;
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VM_OBJECT_RLOCK(backing_object);
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if (object != first_object)
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VM_OBJECT_RUNLOCK(object);
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}
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unlock_return:
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if (object != first_object)
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VM_OBJECT_RUNLOCK(object);
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}
|
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|
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/*
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* deactivate some number of pages in a map, try to do it fairly, but
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* that is really hard to do.
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*/
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static void
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vm_swapout_map_deactivate_pages(vm_map_t map, long desired)
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{
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vm_map_entry_t tmpe;
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vm_object_t obj, bigobj;
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int nothingwired;
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if (!vm_map_trylock_read(map))
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return;
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bigobj = NULL;
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nothingwired = TRUE;
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|
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/*
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* first, search out the biggest object, and try to free pages from
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* that.
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*/
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VM_MAP_ENTRY_FOREACH(tmpe, map) {
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if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) {
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obj = tmpe->object.vm_object;
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if (obj != NULL && VM_OBJECT_TRYRLOCK(obj)) {
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if (obj->shadow_count <= 1 &&
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(bigobj == NULL ||
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bigobj->resident_page_count <
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obj->resident_page_count)) {
|
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if (bigobj != NULL)
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VM_OBJECT_RUNLOCK(bigobj);
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bigobj = obj;
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} else
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VM_OBJECT_RUNLOCK(obj);
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}
|
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}
|
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if (tmpe->wired_count > 0)
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nothingwired = FALSE;
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}
|
|
|
|
if (bigobj != NULL) {
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vm_swapout_object_deactivate(map->pmap, bigobj, desired);
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VM_OBJECT_RUNLOCK(bigobj);
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}
|
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/*
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* Next, hunt around for other pages to deactivate. We actually
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* do this search sort of wrong -- .text first is not the best idea.
|
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*/
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VM_MAP_ENTRY_FOREACH(tmpe, map) {
|
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if (pmap_resident_count(vm_map_pmap(map)) <= desired)
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break;
|
|
if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) {
|
|
obj = tmpe->object.vm_object;
|
|
if (obj != NULL) {
|
|
VM_OBJECT_RLOCK(obj);
|
|
vm_swapout_object_deactivate(map->pmap, obj,
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desired);
|
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VM_OBJECT_RUNLOCK(obj);
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}
|
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}
|
|
}
|
|
|
|
/*
|
|
* Remove all mappings if a process is swapped out, this will free page
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* table pages.
|
|
*/
|
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if (desired == 0 && nothingwired) {
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pmap_remove(vm_map_pmap(map), vm_map_min(map),
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vm_map_max(map));
|
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}
|
|
|
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vm_map_unlock_read(map);
|
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}
|
|
|
|
/*
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|
* Swap out requests
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*/
|
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#define VM_SWAP_NORMAL 1
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#define VM_SWAP_IDLE 2
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|
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void
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|
vm_swapout_run(void)
|
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{
|
|
|
|
if (vm_swap_enabled)
|
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vm_req_vmdaemon(VM_SWAP_NORMAL);
|
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}
|
|
|
|
/*
|
|
* Idle process swapout -- run once per second when pagedaemons are
|
|
* reclaiming pages.
|
|
*/
|
|
void
|
|
vm_swapout_run_idle(void)
|
|
{
|
|
static long lsec;
|
|
|
|
if (!vm_swap_idle_enabled || time_second == lsec)
|
|
return;
|
|
vm_req_vmdaemon(VM_SWAP_IDLE);
|
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lsec = time_second;
|
|
}
|
|
|
|
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);
|
|
msleep(&vm_daemon_needed, &vm_daemon_mtx, PPAUSE, "psleep",
|
|
#ifdef RACCT
|
|
racct_enable ? hz : 0
|
|
#else
|
|
0
|
|
#endif
|
|
);
|
|
swapout_flags = vm_pageout_req_swapout;
|
|
vm_pageout_req_swapout = 0;
|
|
mtx_unlock(&vm_daemon_mtx);
|
|
if (swapout_flags != 0) {
|
|
/*
|
|
* Drain the per-CPU page queue batches as a deadlock
|
|
* avoidance measure.
|
|
*/
|
|
if ((swapout_flags & VM_SWAP_NORMAL) != 0)
|
|
vm_page_pqbatch_drain();
|
|
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_proc(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);
|
|
_PHOLD_LITE(p);
|
|
PROC_UNLOCK(p);
|
|
if (vm == NULL) {
|
|
PRELE(p);
|
|
continue;
|
|
}
|
|
sx_sunlock(&allproc_lock);
|
|
|
|
size = vmspace_resident_count(vm);
|
|
if (size >= limit) {
|
|
vm_swapout_map_deactivate_pages(
|
|
&vm->vm_map, limit);
|
|
size = vmspace_resident_count(vm);
|
|
}
|
|
#ifdef RACCT
|
|
if (racct_enable) {
|
|
rsize = IDX_TO_OFF(size);
|
|
PROC_LOCK(p);
|
|
if (p->p_state == PRS_NORMAL)
|
|
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_swapout_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);
|
|
if (p->p_state == PRS_NORMAL)
|
|
racct_set(p, RACCT_RSS, rsize);
|
|
PROC_UNLOCK(p);
|
|
if (rsize > ravailable)
|
|
tryagain = 1;
|
|
}
|
|
}
|
|
#endif
|
|
vmspace_free(vm);
|
|
sx_slock(&allproc_lock);
|
|
PRELE(p);
|
|
}
|
|
sx_sunlock(&allproc_lock);
|
|
if (tryagain != 0 && attempts <= 10) {
|
|
maybe_yield();
|
|
goto again;
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Allow a thread's kernel stack to be paged out.
|
|
*/
|
|
static void
|
|
vm_thread_swapout(struct thread *td)
|
|
{
|
|
vm_object_t ksobj;
|
|
vm_page_t m;
|
|
int i, pages;
|
|
|
|
cpu_thread_swapout(td);
|
|
pages = td->td_kstack_pages;
|
|
ksobj = td->td_kstack_obj;
|
|
pmap_qremove(td->td_kstack, pages);
|
|
VM_OBJECT_WLOCK(ksobj);
|
|
for (i = 0; i < pages; i++) {
|
|
m = vm_page_lookup(ksobj, i);
|
|
if (m == NULL)
|
|
panic("vm_thread_swapout: kstack already missing?");
|
|
vm_page_dirty(m);
|
|
vm_page_unwire(m, PQ_LAUNDRY);
|
|
}
|
|
VM_OBJECT_WUNLOCK(ksobj);
|
|
}
|
|
|
|
/*
|
|
* Bring the kernel stack for a specified thread back in.
|
|
*/
|
|
static void
|
|
vm_thread_swapin(struct thread *td, int oom_alloc)
|
|
{
|
|
vm_object_t ksobj;
|
|
vm_page_t ma[KSTACK_MAX_PAGES];
|
|
int a, count, i, j, pages, rv;
|
|
|
|
pages = td->td_kstack_pages;
|
|
ksobj = td->td_kstack_obj;
|
|
VM_OBJECT_WLOCK(ksobj);
|
|
(void)vm_page_grab_pages(ksobj, 0, oom_alloc | VM_ALLOC_WIRED, ma,
|
|
pages);
|
|
for (i = 0; i < pages;) {
|
|
vm_page_assert_xbusied(ma[i]);
|
|
if (vm_page_all_valid(ma[i])) {
|
|
vm_page_xunbusy(ma[i]);
|
|
i++;
|
|
continue;
|
|
}
|
|
vm_object_pip_add(ksobj, 1);
|
|
for (j = i + 1; j < pages; j++)
|
|
if (vm_page_all_valid(ma[j]))
|
|
break;
|
|
rv = vm_pager_has_page(ksobj, ma[i]->pindex, NULL, &a);
|
|
KASSERT(rv == 1, ("%s: missing page %p", __func__, ma[i]));
|
|
count = min(a + 1, j - i);
|
|
rv = vm_pager_get_pages(ksobj, ma + i, count, NULL, NULL);
|
|
KASSERT(rv == VM_PAGER_OK, ("%s: cannot get kstack for proc %d",
|
|
__func__, td->td_proc->p_pid));
|
|
vm_object_pip_wakeup(ksobj);
|
|
for (j = i; j < i + count; j++)
|
|
vm_page_xunbusy(ma[j]);
|
|
i += count;
|
|
}
|
|
VM_OBJECT_WUNLOCK(ksobj);
|
|
pmap_qenter(td->td_kstack, ma, pages);
|
|
cpu_thread_swapin(td);
|
|
}
|
|
|
|
void
|
|
faultin(struct proc *p)
|
|
{
|
|
struct thread *td;
|
|
int oom_alloc;
|
|
|
|
PROC_LOCK_ASSERT(p, MA_OWNED);
|
|
|
|
/*
|
|
* If another process is swapping in this process,
|
|
* just wait until it finishes.
|
|
*/
|
|
if (p->p_flag & P_SWAPPINGIN) {
|
|
while (p->p_flag & P_SWAPPINGIN)
|
|
msleep(&p->p_flag, &p->p_mtx, PVM, "faultin", 0);
|
|
return;
|
|
}
|
|
|
|
if ((p->p_flag & P_INMEM) == 0) {
|
|
oom_alloc = (p->p_flag & P_WKILLED) != 0 ? VM_ALLOC_SYSTEM :
|
|
VM_ALLOC_NORMAL;
|
|
|
|
/*
|
|
* Don't let another thread swap process p out while we are
|
|
* busy swapping it in.
|
|
*/
|
|
++p->p_lock;
|
|
p->p_flag |= P_SWAPPINGIN;
|
|
PROC_UNLOCK(p);
|
|
sx_xlock(&allproc_lock);
|
|
MPASS(swapped_cnt > 0);
|
|
swapped_cnt--;
|
|
if (curthread != &thread0)
|
|
swap_inprogress++;
|
|
sx_xunlock(&allproc_lock);
|
|
|
|
/*
|
|
* We hold no lock here because the list of threads
|
|
* can not change while all threads in the process are
|
|
* swapped out.
|
|
*/
|
|
FOREACH_THREAD_IN_PROC(p, td)
|
|
vm_thread_swapin(td, oom_alloc);
|
|
|
|
if (curthread != &thread0) {
|
|
sx_xlock(&allproc_lock);
|
|
MPASS(swap_inprogress > 0);
|
|
swap_inprogress--;
|
|
last_swapin = ticks;
|
|
sx_xunlock(&allproc_lock);
|
|
}
|
|
PROC_LOCK(p);
|
|
swapclear(p);
|
|
p->p_swtick = ticks;
|
|
|
|
/* Allow other threads to swap p out now. */
|
|
wakeup(&p->p_flag);
|
|
--p->p_lock;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* This swapin algorithm attempts to swap-in processes only if there
|
|
* is enough space for them. Of course, if a process waits for a long
|
|
* time, it will be swapped in anyway.
|
|
*/
|
|
|
|
static struct proc *
|
|
swapper_selector(bool wkilled_only)
|
|
{
|
|
struct proc *p, *res;
|
|
struct thread *td;
|
|
int ppri, pri, slptime, swtime;
|
|
|
|
sx_assert(&allproc_lock, SA_SLOCKED);
|
|
if (swapped_cnt == 0)
|
|
return (NULL);
|
|
res = NULL;
|
|
ppri = INT_MIN;
|
|
FOREACH_PROC_IN_SYSTEM(p) {
|
|
PROC_LOCK(p);
|
|
if (p->p_state == PRS_NEW || (p->p_flag & (P_SWAPPINGOUT |
|
|
P_SWAPPINGIN | P_INMEM)) != 0) {
|
|
PROC_UNLOCK(p);
|
|
continue;
|
|
}
|
|
if (p->p_state == PRS_NORMAL && (p->p_flag & P_WKILLED) != 0) {
|
|
/*
|
|
* A swapped-out process might have mapped a
|
|
* large portion of the system's pages as
|
|
* anonymous memory. There is no other way to
|
|
* release the memory other than to kill the
|
|
* process, for which we need to swap it in.
|
|
*/
|
|
return (p);
|
|
}
|
|
if (wkilled_only) {
|
|
PROC_UNLOCK(p);
|
|
continue;
|
|
}
|
|
swtime = (ticks - p->p_swtick) / hz;
|
|
FOREACH_THREAD_IN_PROC(p, td) {
|
|
/*
|
|
* An otherwise runnable thread of a process
|
|
* swapped out has only the TDI_SWAPPED bit set.
|
|
*/
|
|
thread_lock(td);
|
|
if (td->td_inhibitors == TDI_SWAPPED) {
|
|
slptime = (ticks - td->td_slptick) / hz;
|
|
pri = swtime + slptime;
|
|
if ((td->td_flags & TDF_SWAPINREQ) == 0)
|
|
pri -= p->p_nice * 8;
|
|
/*
|
|
* if this thread is higher priority
|
|
* and there is enough space, then select
|
|
* this process instead of the previous
|
|
* selection.
|
|
*/
|
|
if (pri > ppri) {
|
|
res = p;
|
|
ppri = pri;
|
|
}
|
|
}
|
|
thread_unlock(td);
|
|
}
|
|
PROC_UNLOCK(p);
|
|
}
|
|
|
|
if (res != NULL)
|
|
PROC_LOCK(res);
|
|
return (res);
|
|
}
|
|
|
|
#define SWAPIN_INTERVAL (MAXSLP * hz / 2)
|
|
|
|
/*
|
|
* Limit swapper to swap in one non-WKILLED process in MAXSLP/2
|
|
* interval, assuming that there is:
|
|
* - at least one domain that is not suffering from a shortage of free memory;
|
|
* - no parallel swap-ins;
|
|
* - no other swap-ins in the current SWAPIN_INTERVAL.
|
|
*/
|
|
static bool
|
|
swapper_wkilled_only(void)
|
|
{
|
|
|
|
return (vm_page_count_min_set(&all_domains) || swap_inprogress > 0 ||
|
|
(u_int)(ticks - last_swapin) < SWAPIN_INTERVAL);
|
|
}
|
|
|
|
void
|
|
swapper(void)
|
|
{
|
|
struct proc *p;
|
|
|
|
for (;;) {
|
|
sx_slock(&allproc_lock);
|
|
p = swapper_selector(swapper_wkilled_only());
|
|
sx_sunlock(&allproc_lock);
|
|
|
|
if (p == NULL) {
|
|
tsleep(&proc0, PVM, "swapin", SWAPIN_INTERVAL);
|
|
} else {
|
|
PROC_LOCK_ASSERT(p, MA_OWNED);
|
|
|
|
/*
|
|
* Another process may be bringing or may have
|
|
* already brought this process in while we
|
|
* traverse all threads. Or, this process may
|
|
* have exited or even being swapped out
|
|
* again.
|
|
*/
|
|
if (p->p_state == PRS_NORMAL && (p->p_flag & (P_INMEM |
|
|
P_SWAPPINGOUT | P_SWAPPINGIN)) == 0) {
|
|
faultin(p);
|
|
}
|
|
PROC_UNLOCK(p);
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* First, if any processes have been sleeping or stopped for at least
|
|
* "swap_idle_threshold1" seconds, they are swapped out. If, however,
|
|
* no such processes exist, then the longest-sleeping or stopped
|
|
* process is swapped out. Finally, and only as a last resort, if
|
|
* there are no sleeping or stopped processes, the longest-resident
|
|
* process is swapped out.
|
|
*/
|
|
static void
|
|
swapout_procs(int action)
|
|
{
|
|
struct proc *p;
|
|
struct thread *td;
|
|
int slptime;
|
|
bool didswap, doswap;
|
|
|
|
MPASS((action & (VM_SWAP_NORMAL | VM_SWAP_IDLE)) != 0);
|
|
|
|
didswap = false;
|
|
sx_slock(&allproc_lock);
|
|
FOREACH_PROC_IN_SYSTEM(p) {
|
|
/*
|
|
* Filter out not yet fully constructed processes. Do
|
|
* not swap out held processes. Avoid processes which
|
|
* are system, exiting, execing, traced, already swapped
|
|
* out or are in the process of being swapped in or out.
|
|
*/
|
|
PROC_LOCK(p);
|
|
if (p->p_state != PRS_NORMAL || p->p_lock != 0 || (p->p_flag &
|
|
(P_SYSTEM | P_WEXIT | P_INEXEC | P_STOPPED_SINGLE |
|
|
P_TRACED | P_SWAPPINGOUT | P_SWAPPINGIN | P_INMEM)) !=
|
|
P_INMEM) {
|
|
PROC_UNLOCK(p);
|
|
continue;
|
|
}
|
|
|
|
/*
|
|
* Further consideration of this process for swap out
|
|
* requires iterating over its threads. We release
|
|
* allproc_lock here so that process creation and
|
|
* destruction are not blocked while we iterate.
|
|
*
|
|
* To later reacquire allproc_lock and resume
|
|
* iteration over the allproc list, we will first have
|
|
* to release the lock on the process. We place a
|
|
* hold on the process so that it remains in the
|
|
* allproc list while it is unlocked.
|
|
*/
|
|
_PHOLD_LITE(p);
|
|
sx_sunlock(&allproc_lock);
|
|
|
|
/*
|
|
* Do not swapout a realtime process.
|
|
* Guarantee swap_idle_threshold1 time in memory.
|
|
* If the system is under memory stress, or if we are
|
|
* swapping idle processes >= swap_idle_threshold2,
|
|
* then swap the process out.
|
|
*/
|
|
doswap = true;
|
|
FOREACH_THREAD_IN_PROC(p, td) {
|
|
thread_lock(td);
|
|
slptime = (ticks - td->td_slptick) / hz;
|
|
if (PRI_IS_REALTIME(td->td_pri_class) ||
|
|
slptime < swap_idle_threshold1 ||
|
|
!thread_safetoswapout(td) ||
|
|
((action & VM_SWAP_NORMAL) == 0 &&
|
|
slptime < swap_idle_threshold2))
|
|
doswap = false;
|
|
thread_unlock(td);
|
|
if (!doswap)
|
|
break;
|
|
}
|
|
if (doswap && swapout(p) == 0)
|
|
didswap = true;
|
|
|
|
PROC_UNLOCK(p);
|
|
if (didswap) {
|
|
sx_xlock(&allproc_lock);
|
|
swapped_cnt++;
|
|
sx_downgrade(&allproc_lock);
|
|
} else
|
|
sx_slock(&allproc_lock);
|
|
PRELE(p);
|
|
}
|
|
sx_sunlock(&allproc_lock);
|
|
|
|
/*
|
|
* If we swapped something out, and another process needed memory,
|
|
* then wakeup the sched process.
|
|
*/
|
|
if (didswap)
|
|
wakeup(&proc0);
|
|
}
|
|
|
|
static void
|
|
swapclear(struct proc *p)
|
|
{
|
|
struct thread *td;
|
|
|
|
PROC_LOCK_ASSERT(p, MA_OWNED);
|
|
|
|
FOREACH_THREAD_IN_PROC(p, td) {
|
|
thread_lock(td);
|
|
td->td_flags |= TDF_INMEM;
|
|
td->td_flags &= ~TDF_SWAPINREQ;
|
|
TD_CLR_SWAPPED(td);
|
|
if (TD_CAN_RUN(td)) {
|
|
if (setrunnable(td, 0)) {
|
|
#ifdef INVARIANTS
|
|
/*
|
|
* XXX: We just cleared TDI_SWAPPED
|
|
* above and set TDF_INMEM, so this
|
|
* should never happen.
|
|
*/
|
|
panic("not waking up swapper");
|
|
#endif
|
|
}
|
|
} else
|
|
thread_unlock(td);
|
|
}
|
|
p->p_flag &= ~(P_SWAPPINGIN | P_SWAPPINGOUT);
|
|
p->p_flag |= P_INMEM;
|
|
}
|
|
|
|
static int
|
|
swapout(struct proc *p)
|
|
{
|
|
struct thread *td;
|
|
|
|
PROC_LOCK_ASSERT(p, MA_OWNED);
|
|
|
|
/*
|
|
* The states of this process and its threads may have changed
|
|
* by now. Assuming that there is only one pageout daemon thread,
|
|
* this process should still be in memory.
|
|
*/
|
|
KASSERT((p->p_flag & (P_INMEM | P_SWAPPINGOUT | P_SWAPPINGIN)) ==
|
|
P_INMEM, ("swapout: lost a swapout race?"));
|
|
|
|
/*
|
|
* Remember the resident count.
|
|
*/
|
|
p->p_vmspace->vm_swrss = vmspace_resident_count(p->p_vmspace);
|
|
|
|
/*
|
|
* Check and mark all threads before we proceed.
|
|
*/
|
|
p->p_flag &= ~P_INMEM;
|
|
p->p_flag |= P_SWAPPINGOUT;
|
|
FOREACH_THREAD_IN_PROC(p, td) {
|
|
thread_lock(td);
|
|
if (!thread_safetoswapout(td)) {
|
|
thread_unlock(td);
|
|
swapclear(p);
|
|
return (EBUSY);
|
|
}
|
|
td->td_flags &= ~TDF_INMEM;
|
|
TD_SET_SWAPPED(td);
|
|
thread_unlock(td);
|
|
}
|
|
td = FIRST_THREAD_IN_PROC(p);
|
|
++td->td_ru.ru_nswap;
|
|
PROC_UNLOCK(p);
|
|
|
|
/*
|
|
* This list is stable because all threads are now prevented from
|
|
* running. The list is only modified in the context of a running
|
|
* thread in this process.
|
|
*/
|
|
FOREACH_THREAD_IN_PROC(p, td)
|
|
vm_thread_swapout(td);
|
|
|
|
PROC_LOCK(p);
|
|
p->p_flag &= ~P_SWAPPINGOUT;
|
|
p->p_swtick = ticks;
|
|
return (0);
|
|
}
|