ebcddc7217
pages, specificially, dirty pages that have passed once through the inactive
queue. A new, dedicated thread is responsible for both deciding when to
launder pages and actually laundering them. The new policy uses the
relative sizes of the inactive and laundry queues to determine whether to
launder pages at a given point in time. In general, this leads to more
intelligent swapping behavior, since the laundry thread will avoid pageouts
when the marginal benefit of doing so is low. Previously, without a
dedicated queue for dirty pages, the page daemon didn't have the information
to determine whether pageout provides any benefit to the system. Thus, the
previous policy often resulted in small but steadily increasing amounts of
swap usage when the system is under memory pressure, even when the inactive
queue consisted mostly of clean pages. This change addresses that issue,
and also paves the way for some future virtual memory system improvements by
removing the last source of object-cached clean pages, i.e., PG_CACHE pages.
The new laundry thread sleeps while waiting for a request from the page
daemon thread(s). A request is raised by setting the variable
vm_laundry_request and waking the laundry thread. We request launderings
for two reasons: to try and balance the inactive and laundry queue sizes
("background laundering"), and to quickly make up for a shortage of free
pages and clean inactive pages ("shortfall laundering"). When background
laundering is requested, the laundry thread computes the number of page
daemon wakeups that have taken place since the last laundering. If this
number is large enough relative to the ratio of the laundry and (global)
inactive queue sizes, we will launder vm_background_launder_target pages at
vm_background_launder_rate KB/s. Otherwise, the laundry thread goes back
to sleep without doing any work. When scanning the laundry queue during
background laundering, reactivated pages are counted towards the laundry
thread's target.
In contrast, shortfall laundering is requested when an inactive queue scan
fails to meet its target. In this case, the laundry thread attempts to
launder enough pages to meet v_free_target within 0.5s, which is the
inactive queue scan period.
A laundry request can be latched while another is currently being
serviced. In particular, a shortfall request will immediately preempt a
background laundering.
This change also redefines the meaning of vm_cnt.v_reactivated and removes
the functions vm_page_cache() and vm_page_try_to_cache(). The new meaning
of vm_cnt.v_reactivated now better reflects its name. It represents the
number of inactive or laundry pages that are returned to the active queue
on account of a reference.
In collaboration with: markj
Reviewed by: kib
Tested by: pho
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D8302
2267 lines
64 KiB
C
2267 lines
64 KiB
C
/*-
|
|
* 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.
|
|
* Copyright (c) 2005 Yahoo! Technologies Norway AS
|
|
* All rights reserved.
|
|
*
|
|
* This code is derived from software contributed to Berkeley by
|
|
* The Mach Operating System project at Carnegie-Mellon University.
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
* 1. Redistributions of source code must retain the above copyright
|
|
* notice, this list of conditions and the following disclaimer.
|
|
* 2. Redistributions in binary form must reproduce the above copyright
|
|
* notice, this list of conditions and the following disclaimer in the
|
|
* documentation and/or other materials provided with the distribution.
|
|
* 3. All advertising materials mentioning features or use of this software
|
|
* must display the following acknowledgement:
|
|
* This product includes software developed by the University of
|
|
* California, Berkeley and its contributors.
|
|
* 4. Neither the name of the University nor the names of its contributors
|
|
* may be used to endorse or promote products derived from this software
|
|
* without specific prior written permission.
|
|
*
|
|
* 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
|
|
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
* 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
|
|
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
* SUCH DAMAGE.
|
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*
|
|
* from: @(#)vm_pageout.c 7.4 (Berkeley) 5/7/91
|
|
*
|
|
*
|
|
* Copyright (c) 1987, 1990 Carnegie-Mellon University.
|
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* All rights reserved.
|
|
*
|
|
* Authors: Avadis Tevanian, Jr., Michael Wayne Young
|
|
*
|
|
* 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
|
|
* 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.
|
|
*
|
|
* Carnegie Mellon requests users of this software to return to
|
|
*
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|
* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
|
|
* School of Computer Science
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|
* Carnegie Mellon University
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|
* Pittsburgh PA 15213-3890
|
|
*
|
|
* any improvements or extensions that they make and grant Carnegie the
|
|
* rights to redistribute these changes.
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|
*/
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|
|
|
/*
|
|
* The proverbial page-out daemon.
|
|
*/
|
|
|
|
#include <sys/cdefs.h>
|
|
__FBSDID("$FreeBSD$");
|
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|
|
#include "opt_vm.h"
|
|
|
|
#include <sys/param.h>
|
|
#include <sys/systm.h>
|
|
#include <sys/kernel.h>
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|
#include <sys/eventhandler.h>
|
|
#include <sys/lock.h>
|
|
#include <sys/mutex.h>
|
|
#include <sys/proc.h>
|
|
#include <sys/kthread.h>
|
|
#include <sys/ktr.h>
|
|
#include <sys/mount.h>
|
|
#include <sys/racct.h>
|
|
#include <sys/resourcevar.h>
|
|
#include <sys/sched.h>
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|
#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>
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|
#include <sys/sx.h>
|
|
#include <sys/sysctl.h>
|
|
|
|
#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>
|
|
#include <vm/swap_pager.h>
|
|
#include <vm/vm_extern.h>
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|
#include <vm/uma.h>
|
|
|
|
/*
|
|
* System initialization
|
|
*/
|
|
|
|
/* the kernel process "vm_pageout"*/
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|
static void vm_pageout(void);
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|
static void vm_pageout_init(void);
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|
static int vm_pageout_clean(vm_page_t m, int *numpagedout);
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static int vm_pageout_cluster(vm_page_t m);
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static bool vm_pageout_scan(struct vm_domain *vmd, int pass);
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|
static void vm_pageout_mightbe_oom(struct vm_domain *vmd, int page_shortage,
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int starting_page_shortage);
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|
SYSINIT(pagedaemon_init, SI_SUB_KTHREAD_PAGE, SI_ORDER_FIRST, vm_pageout_init,
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NULL);
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struct proc *pageproc;
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|
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static struct kproc_desc page_kp = {
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"pagedaemon",
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vm_pageout,
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&pageproc
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};
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SYSINIT(pagedaemon, SI_SUB_KTHREAD_PAGE, SI_ORDER_SECOND, kproc_start,
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&page_kp);
|
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|
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SDT_PROVIDER_DEFINE(vm);
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SDT_PROBE_DEFINE(vm, , , vm__lowmem_scan);
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|
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#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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/* Pagedaemon activity rates, in subdivisions of one second. */
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#define VM_LAUNDER_RATE 10
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#define VM_INACT_SCAN_RATE 2
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int vm_pageout_deficit; /* Estimated number of pages deficit */
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u_int vm_pageout_wakeup_thresh;
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static int vm_pageout_oom_seq = 12;
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bool vm_pageout_wanted; /* Event on which pageout daemon sleeps */
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bool vm_pages_needed; /* Are threads waiting for free pages? */
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/* Pending request for dirty page laundering. */
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static enum {
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VM_LAUNDRY_IDLE,
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VM_LAUNDRY_BACKGROUND,
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VM_LAUNDRY_SHORTFALL
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} vm_laundry_request = VM_LAUNDRY_IDLE;
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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_pageout_update_period;
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static int disable_swap_pageouts;
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static int lowmem_period = 10;
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static time_t lowmem_uptime;
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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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|
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static int vm_panic_on_oom = 0;
|
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SYSCTL_INT(_vm, OID_AUTO, panic_on_oom,
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CTLFLAG_RWTUN, &vm_panic_on_oom, 0,
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"panic on out of memory instead of killing the largest process");
|
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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, 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, disable_swapspace_pageouts,
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CTLFLAG_RW, &disable_swap_pageouts, 0, "Disallow swapout of dirty pages");
|
|
|
|
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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|
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SYSCTL_INT(_vm, OID_AUTO, pageout_oom_seq,
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CTLFLAG_RW, &vm_pageout_oom_seq, 0,
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"back-to-back calls to oom detector to start OOM");
|
|
|
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static int act_scan_laundry_weight = 3;
|
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SYSCTL_INT(_vm, OID_AUTO, act_scan_laundry_weight, CTLFLAG_RW,
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&act_scan_laundry_weight, 0,
|
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"weight given to clean vs. dirty pages in active queue scans");
|
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|
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static u_int vm_background_launder_target;
|
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SYSCTL_UINT(_vm, OID_AUTO, background_launder_target, CTLFLAG_RW,
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&vm_background_launder_target, 0,
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"background laundering target, in pages");
|
|
|
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static u_int vm_background_launder_rate = 4096;
|
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SYSCTL_UINT(_vm, OID_AUTO, background_launder_rate, CTLFLAG_RW,
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&vm_background_launder_rate, 0,
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"background laundering rate, in kilobytes per second");
|
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static u_int vm_background_launder_max = 20 * 1024;
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SYSCTL_UINT(_vm, OID_AUTO, background_launder_max, CTLFLAG_RW,
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&vm_background_launder_max, 0, "background laundering cap, in kilobytes");
|
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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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|
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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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|
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static u_int isqrt(u_int num);
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static boolean_t vm_pageout_fallback_object_lock(vm_page_t, vm_page_t *);
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static int vm_pageout_launder(struct vm_domain *vmd, int launder,
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bool in_shortfall);
|
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static void vm_pageout_laundry_worker(void *arg);
|
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#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 write busies and initializes the hold count
|
|
* to one as safety precautions.
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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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|
|
|
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 queue
|
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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
|
|
* locked on return.
|
|
*
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|
* This function depends on both the lock portion of struct vm_object
|
|
* and normal struct vm_page being type stable.
|
|
*/
|
|
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;
|
|
boolean_t unchanged;
|
|
u_short queue;
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vm_object_t object;
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|
|
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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;
|
|
|
|
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);
|
|
|
|
/*
|
|
* The page's object might have changed, and/or the page might
|
|
* have moved from its original position in the queue. If the
|
|
* page's object has changed, then the caller should abandon
|
|
* processing the page because the wrong object lock was
|
|
* acquired. Use the marker's plinks.q, not the page's, to
|
|
* determine if the page has been moved. The state of the
|
|
* page's plinks.q can be indeterminate; whereas, the marker's
|
|
* plinks.q must be valid.
|
|
*/
|
|
*next = TAILQ_NEXT(&marker, plinks.q);
|
|
unchanged = m->object == object &&
|
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m == TAILQ_PREV(&marker, pglist, plinks.q);
|
|
KASSERT(!unchanged || m->queue == queue,
|
|
("page %p queue %d %d", m, queue, m->queue));
|
|
TAILQ_REMOVE(&pq->pq_pl, &marker, plinks.q);
|
|
return (unchanged);
|
|
}
|
|
|
|
/*
|
|
* Lock the page while holding the page queue lock. Use marker page
|
|
* to detect page queue changes and maintain notion of next page on
|
|
* page queue. Return TRUE if no changes were detected, FALSE
|
|
* otherwise. The page is locked on return. The page queue lock might
|
|
* be dropped and reacquired.
|
|
*
|
|
* This function depends on normal struct vm_page being type stable.
|
|
*/
|
|
static boolean_t
|
|
vm_pageout_page_lock(vm_page_t m, vm_page_t *next)
|
|
{
|
|
struct vm_page marker;
|
|
struct vm_pagequeue *pq;
|
|
boolean_t unchanged;
|
|
u_short queue;
|
|
|
|
vm_page_lock_assert(m, MA_NOTOWNED);
|
|
if (vm_page_trylock(m))
|
|
return (TRUE);
|
|
|
|
queue = m->queue;
|
|
vm_pageout_init_marker(&marker, queue);
|
|
pq = vm_page_pagequeue(m);
|
|
|
|
TAILQ_INSERT_AFTER(&pq->pq_pl, m, &marker, plinks.q);
|
|
vm_pagequeue_unlock(pq);
|
|
vm_page_lock(m);
|
|
vm_pagequeue_lock(pq);
|
|
|
|
/* Page queue might have changed. */
|
|
*next = TAILQ_NEXT(&marker, plinks.q);
|
|
unchanged = m == TAILQ_PREV(&marker, pglist, plinks.q);
|
|
KASSERT(!unchanged || m->queue == queue,
|
|
("page %p queue %d %d", m, queue, m->queue));
|
|
TAILQ_REMOVE(&pq->pq_pl, &marker, plinks.q);
|
|
return (unchanged);
|
|
}
|
|
|
|
/*
|
|
* Scan for pages at adjacent offsets within the given page's object that are
|
|
* eligible for laundering, form a cluster of these pages and the given page,
|
|
* and launder that cluster.
|
|
*/
|
|
static int
|
|
vm_pageout_cluster(vm_page_t m)
|
|
{
|
|
vm_object_t object;
|
|
vm_page_t mc[2 * vm_pageout_page_count], p, pb, ps;
|
|
vm_pindex_t pindex;
|
|
int ib, is, page_base, pageout_count;
|
|
|
|
vm_page_assert_locked(m);
|
|
object = m->object;
|
|
VM_OBJECT_ASSERT_WLOCKED(object);
|
|
pindex = m->pindex;
|
|
|
|
/*
|
|
* We can't clean the page if it is busy or held.
|
|
*/
|
|
vm_page_assert_unbusied(m);
|
|
KASSERT(m->hold_count == 0, ("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;
|
|
|
|
/*
|
|
* We can cluster only if the page is not clean, busy, or held, and
|
|
* the page is in the laundry queue.
|
|
*
|
|
* During heavy mmap/modification loads the pageout
|
|
* daemon can really fragment the underlying file
|
|
* due to flushing pages out of order and not trying to
|
|
* align the clusters (which leaves sporadic out-of-order
|
|
* holes). To solve this problem we do the reverse scan
|
|
* first and attempt to align our cluster, then do a
|
|
* forward scan if room remains.
|
|
*/
|
|
more:
|
|
while (ib != 0 && pageout_count < vm_pageout_page_count) {
|
|
if (ib > pindex) {
|
|
ib = 0;
|
|
break;
|
|
}
|
|
if ((p = vm_page_prev(pb)) == NULL || vm_page_busied(p)) {
|
|
ib = 0;
|
|
break;
|
|
}
|
|
vm_page_test_dirty(p);
|
|
if (p->dirty == 0) {
|
|
ib = 0;
|
|
break;
|
|
}
|
|
vm_page_lock(p);
|
|
if (!vm_page_in_laundry(p) ||
|
|
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;
|
|
|
|
/*
|
|
* We are at an alignment boundary. Stop here, and switch
|
|
* directions. Do not clear ib.
|
|
*/
|
|
if ((pindex - (ib - 1)) % vm_pageout_page_count == 0)
|
|
break;
|
|
}
|
|
while (pageout_count < vm_pageout_page_count &&
|
|
pindex + is < object->size) {
|
|
if ((p = vm_page_next(ps)) == NULL || vm_page_busied(p))
|
|
break;
|
|
vm_page_test_dirty(p);
|
|
if (p->dirty == 0)
|
|
break;
|
|
vm_page_lock(p);
|
|
if (!vm_page_in_laundry(p) ||
|
|
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 an alignment boundary. This catches
|
|
* boundary conditions.
|
|
*/
|
|
if (ib != 0 && pageout_count < vm_pageout_page_count)
|
|
goto more;
|
|
|
|
return (vm_pageout_flush(&mc[page_base], pageout_count, 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:
|
|
vm_page_lock(mt);
|
|
if (vm_page_in_laundry(mt))
|
|
vm_page_deactivate_noreuse(mt);
|
|
vm_page_unlock(mt);
|
|
/* FALLTHROUGH */
|
|
case VM_PAGER_PEND:
|
|
numpagedout++;
|
|
break;
|
|
case VM_PAGER_BAD:
|
|
/*
|
|
* The page is outside the object's range. We pretend
|
|
* that the page out worked and clean the page, so the
|
|
* changes will be lost if the page is reclaimed by
|
|
* the page daemon.
|
|
*/
|
|
vm_page_undirty(mt);
|
|
vm_page_lock(mt);
|
|
if (vm_page_in_laundry(mt))
|
|
vm_page_deactivate_noreuse(mt);
|
|
vm_page_unlock(mt);
|
|
break;
|
|
case VM_PAGER_ERROR:
|
|
case VM_PAGER_FAIL:
|
|
/*
|
|
* If the page couldn't be paged out, then reactivate
|
|
* it so that it doesn't clog the laundry and inactive
|
|
* queues. (We will try paging it out 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 (prunlen != NULL)
|
|
*prunlen = runlen;
|
|
return (numpagedout);
|
|
}
|
|
|
|
#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 (!vm_page_active(p) && act_delta != 0) {
|
|
vm_page_activate(p);
|
|
p->act_count += act_delta;
|
|
} else if (vm_page_active(p)) {
|
|
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 (vm_page_inactive(p))
|
|
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;
|
|
}
|
|
|
|
/*
|
|
* 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));
|
|
}
|
|
|
|
vm_map_unlock(map);
|
|
}
|
|
#endif /* !defined(NO_SWAPPING) */
|
|
|
|
/*
|
|
* Attempt to acquire all of the necessary locks to launder a page and
|
|
* then call through the clustering layer to PUTPAGES. Wait a short
|
|
* time for a vnode lock.
|
|
*
|
|
* Requires the page and object lock on entry, releases both before return.
|
|
* Returns 0 on success and an errno otherwise.
|
|
*/
|
|
static int
|
|
vm_pageout_clean(vm_page_t m, int *numpagedout)
|
|
{
|
|
struct vnode *vp;
|
|
struct mount *mp;
|
|
vm_object_t object;
|
|
vm_pindex_t pindex;
|
|
int error, lockmode;
|
|
|
|
vm_page_assert_locked(m);
|
|
object = m->object;
|
|
VM_OBJECT_ASSERT_WLOCKED(object);
|
|
error = 0;
|
|
vp = NULL;
|
|
mp = NULL;
|
|
|
|
/*
|
|
* The object is already known NOT to be dead. It
|
|
* is possible for the vget() to block the whole
|
|
* pageout daemon, but the new low-memory handling
|
|
* code should prevent it.
|
|
*
|
|
* We can't wait forever for the vnode lock, we might
|
|
* deadlock due to a vn_read() getting stuck in
|
|
* vm_wait while holding this vnode. We skip the
|
|
* vnode if we can't get it in a reasonable amount
|
|
* of time.
|
|
*/
|
|
if (object->type == OBJT_VNODE) {
|
|
vm_page_unlock(m);
|
|
vp = object->handle;
|
|
if (vp->v_type == VREG &&
|
|
vn_start_write(vp, &mp, V_NOWAIT) != 0) {
|
|
mp = NULL;
|
|
error = EDEADLK;
|
|
goto unlock_all;
|
|
}
|
|
KASSERT(mp != NULL,
|
|
("vp %p with NULL v_mount", vp));
|
|
vm_object_reference_locked(object);
|
|
pindex = m->pindex;
|
|
VM_OBJECT_WUNLOCK(object);
|
|
lockmode = MNT_SHARED_WRITES(vp->v_mount) ?
|
|
LK_SHARED : LK_EXCLUSIVE;
|
|
if (vget(vp, lockmode | LK_TIMELOCK, curthread)) {
|
|
vp = NULL;
|
|
error = EDEADLK;
|
|
goto unlock_mp;
|
|
}
|
|
VM_OBJECT_WLOCK(object);
|
|
vm_page_lock(m);
|
|
/*
|
|
* While the object and page were unlocked, the page
|
|
* may have been:
|
|
* (1) moved to a different queue,
|
|
* (2) reallocated to a different object,
|
|
* (3) reallocated to a different offset, or
|
|
* (4) cleaned.
|
|
*/
|
|
if (!vm_page_in_laundry(m) || m->object != object ||
|
|
m->pindex != pindex || m->dirty == 0) {
|
|
vm_page_unlock(m);
|
|
error = ENXIO;
|
|
goto unlock_all;
|
|
}
|
|
|
|
/*
|
|
* The page may have been busied or held while the object
|
|
* and page locks were released.
|
|
*/
|
|
if (vm_page_busied(m) || m->hold_count != 0) {
|
|
vm_page_unlock(m);
|
|
error = EBUSY;
|
|
goto unlock_all;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* If a page is dirty, then it is either being washed
|
|
* (but not yet cleaned) or it is still in the
|
|
* laundry. If it is still in the laundry, then we
|
|
* start the cleaning operation.
|
|
*/
|
|
if ((*numpagedout = vm_pageout_cluster(m)) == 0)
|
|
error = EIO;
|
|
|
|
unlock_all:
|
|
VM_OBJECT_WUNLOCK(object);
|
|
|
|
unlock_mp:
|
|
vm_page_lock_assert(m, MA_NOTOWNED);
|
|
if (mp != NULL) {
|
|
if (vp != NULL)
|
|
vput(vp);
|
|
vm_object_deallocate(object);
|
|
vn_finished_write(mp);
|
|
}
|
|
|
|
return (error);
|
|
}
|
|
|
|
/*
|
|
* Attempt to launder the specified number of pages.
|
|
*
|
|
* Returns the number of pages successfully laundered.
|
|
*/
|
|
static int
|
|
vm_pageout_launder(struct vm_domain *vmd, int launder, bool in_shortfall)
|
|
{
|
|
struct vm_pagequeue *pq;
|
|
vm_object_t object;
|
|
vm_page_t m, next;
|
|
int act_delta, error, maxscan, numpagedout, starting_target;
|
|
int vnodes_skipped;
|
|
bool pageout_ok, queue_locked;
|
|
|
|
starting_target = launder;
|
|
vnodes_skipped = 0;
|
|
|
|
/*
|
|
* Scan the laundry queue for pages eligible to be laundered. We stop
|
|
* once the target number of dirty pages have been laundered, or once
|
|
* we've reached the end of the queue. A single iteration of this loop
|
|
* may cause more than one page to be laundered because of clustering.
|
|
*
|
|
* maxscan ensures that we don't re-examine requeued pages. Any
|
|
* additional pages written as part of a cluster are subtracted from
|
|
* maxscan since they must be taken from the laundry queue.
|
|
*/
|
|
pq = &vmd->vmd_pagequeues[PQ_LAUNDRY];
|
|
maxscan = pq->pq_cnt;
|
|
|
|
vm_pagequeue_lock(pq);
|
|
queue_locked = true;
|
|
for (m = TAILQ_FIRST(&pq->pq_pl);
|
|
m != NULL && maxscan-- > 0 && launder > 0;
|
|
m = next) {
|
|
vm_pagequeue_assert_locked(pq);
|
|
KASSERT(queue_locked, ("unlocked laundry queue"));
|
|
KASSERT(vm_page_in_laundry(m),
|
|
("page %p has an inconsistent queue", m));
|
|
next = TAILQ_NEXT(m, plinks.q);
|
|
if ((m->flags & PG_MARKER) != 0)
|
|
continue;
|
|
KASSERT((m->flags & PG_FICTITIOUS) == 0,
|
|
("PG_FICTITIOUS page %p cannot be in laundry queue", m));
|
|
KASSERT((m->oflags & VPO_UNMANAGED) == 0,
|
|
("VPO_UNMANAGED page %p cannot be in laundry queue", m));
|
|
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_OBJECT_WUNLOCK(object);
|
|
vm_page_unlock(m);
|
|
continue;
|
|
}
|
|
|
|
/*
|
|
* Unlock the laundry queue, invalidating the 'next' pointer.
|
|
* Use a marker to remember our place in the laundry queue.
|
|
*/
|
|
TAILQ_INSERT_AFTER(&pq->pq_pl, m, &vmd->vmd_laundry_marker,
|
|
plinks.q);
|
|
vm_pagequeue_unlock(pq);
|
|
queue_locked = false;
|
|
|
|
/*
|
|
* Invalid pages can be easily freed. They cannot be
|
|
* mapped; vm_page_free() asserts this.
|
|
*/
|
|
if (m->valid == 0)
|
|
goto free_page;
|
|
|
|
/*
|
|
* If the page has been referenced and the object is not dead,
|
|
* reactivate or requeue the page depending on whether the
|
|
* object is mapped.
|
|
*/
|
|
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),
|
|
("page %p is mapped", m));
|
|
}
|
|
if (act_delta != 0) {
|
|
if (object->ref_count != 0) {
|
|
PCPU_INC(cnt.v_reactivated);
|
|
vm_page_activate(m);
|
|
|
|
/*
|
|
* Increase the activation count if the page
|
|
* was referenced while in the laundry queue.
|
|
* This makes it less likely that the page will
|
|
* be returned prematurely to the inactive
|
|
* queue.
|
|
*/
|
|
m->act_count += act_delta + ACT_ADVANCE;
|
|
|
|
/*
|
|
* If this was a background laundering, count
|
|
* activated pages towards our target. The
|
|
* purpose of background laundering is to ensure
|
|
* that pages are eventually cycled through the
|
|
* laundry queue, and an activation is a valid
|
|
* way out.
|
|
*/
|
|
if (!in_shortfall)
|
|
launder--;
|
|
goto drop_page;
|
|
} else if ((object->flags & OBJ_DEAD) == 0)
|
|
goto requeue_page;
|
|
}
|
|
|
|
/*
|
|
* If the page appears to be clean at the machine-independent
|
|
* layer, then remove all of its mappings from the pmap in
|
|
* anticipation of freeing it. If, however, any of the page's
|
|
* mappings allow write access, then the page may still be
|
|
* modified until the last of those mappings are removed.
|
|
*/
|
|
if (object->ref_count != 0) {
|
|
vm_page_test_dirty(m);
|
|
if (m->dirty == 0)
|
|
pmap_remove_all(m);
|
|
}
|
|
|
|
/*
|
|
* Clean pages are freed, and dirty pages are paged out unless
|
|
* they belong to a dead object. Requeueing dirty pages from
|
|
* dead objects is pointless, as they are being paged out and
|
|
* freed by the thread that destroyed the object.
|
|
*/
|
|
if (m->dirty == 0) {
|
|
free_page:
|
|
vm_page_free(m);
|
|
PCPU_INC(cnt.v_dfree);
|
|
} else if ((object->flags & OBJ_DEAD) == 0) {
|
|
if (object->type != OBJT_SWAP &&
|
|
object->type != OBJT_DEFAULT)
|
|
pageout_ok = true;
|
|
else if (disable_swap_pageouts)
|
|
pageout_ok = false;
|
|
else
|
|
pageout_ok = true;
|
|
if (!pageout_ok) {
|
|
requeue_page:
|
|
vm_pagequeue_lock(pq);
|
|
queue_locked = true;
|
|
vm_page_requeue_locked(m);
|
|
goto drop_page;
|
|
}
|
|
|
|
/*
|
|
* Form a cluster with adjacent, dirty pages from the
|
|
* same object, and page out that entire cluster.
|
|
*
|
|
* The adjacent, dirty pages must also be in the
|
|
* laundry. However, their mappings are not checked
|
|
* for new references. Consequently, a recently
|
|
* referenced page may be paged out. However, that
|
|
* page will not be prematurely reclaimed. After page
|
|
* out, the page will be placed in the inactive queue,
|
|
* where any new references will be detected and the
|
|
* page reactivated.
|
|
*/
|
|
error = vm_pageout_clean(m, &numpagedout);
|
|
if (error == 0) {
|
|
launder -= numpagedout;
|
|
maxscan -= numpagedout - 1;
|
|
} else if (error == EDEADLK) {
|
|
pageout_lock_miss++;
|
|
vnodes_skipped++;
|
|
}
|
|
goto relock_queue;
|
|
}
|
|
drop_page:
|
|
vm_page_unlock(m);
|
|
VM_OBJECT_WUNLOCK(object);
|
|
relock_queue:
|
|
if (!queue_locked) {
|
|
vm_pagequeue_lock(pq);
|
|
queue_locked = true;
|
|
}
|
|
next = TAILQ_NEXT(&vmd->vmd_laundry_marker, plinks.q);
|
|
TAILQ_REMOVE(&pq->pq_pl, &vmd->vmd_laundry_marker, plinks.q);
|
|
}
|
|
vm_pagequeue_unlock(pq);
|
|
|
|
/*
|
|
* Wakeup the sync daemon if we skipped a vnode in a writeable object
|
|
* and we didn't launder enough pages.
|
|
*/
|
|
if (vnodes_skipped > 0 && launder > 0)
|
|
(void)speedup_syncer();
|
|
|
|
return (starting_target - launder);
|
|
}
|
|
|
|
/*
|
|
* Compute the integer square root.
|
|
*/
|
|
static u_int
|
|
isqrt(u_int num)
|
|
{
|
|
u_int bit, root, tmp;
|
|
|
|
bit = 1u << ((NBBY * sizeof(u_int)) - 2);
|
|
while (bit > num)
|
|
bit >>= 2;
|
|
root = 0;
|
|
while (bit != 0) {
|
|
tmp = root + bit;
|
|
root >>= 1;
|
|
if (num >= tmp) {
|
|
num -= tmp;
|
|
root += bit;
|
|
}
|
|
bit >>= 2;
|
|
}
|
|
return (root);
|
|
}
|
|
|
|
/*
|
|
* Perform the work of the laundry thread: periodically wake up and determine
|
|
* whether any pages need to be laundered. If so, determine the number of pages
|
|
* that need to be laundered, and launder them.
|
|
*/
|
|
static void
|
|
vm_pageout_laundry_worker(void *arg)
|
|
{
|
|
struct vm_domain *domain;
|
|
struct vm_pagequeue *pq;
|
|
uint64_t nclean, ndirty;
|
|
u_int last_launder, wakeups;
|
|
int domidx, last_target, launder, shortfall, shortfall_cycle, target;
|
|
bool in_shortfall;
|
|
|
|
domidx = (uintptr_t)arg;
|
|
domain = &vm_dom[domidx];
|
|
pq = &domain->vmd_pagequeues[PQ_LAUNDRY];
|
|
KASSERT(domain->vmd_segs != 0, ("domain without segments"));
|
|
vm_pageout_init_marker(&domain->vmd_laundry_marker, PQ_LAUNDRY);
|
|
|
|
shortfall = 0;
|
|
in_shortfall = false;
|
|
shortfall_cycle = 0;
|
|
target = 0;
|
|
last_launder = 0;
|
|
|
|
/*
|
|
* The pageout laundry worker is never done, so loop forever.
|
|
*/
|
|
for (;;) {
|
|
KASSERT(target >= 0, ("negative target %d", target));
|
|
KASSERT(shortfall_cycle >= 0,
|
|
("negative cycle %d", shortfall_cycle));
|
|
launder = 0;
|
|
wakeups = VM_METER_PCPU_CNT(v_pdwakeups);
|
|
|
|
/*
|
|
* First determine whether we need to launder pages to meet a
|
|
* shortage of free pages.
|
|
*/
|
|
if (shortfall > 0) {
|
|
in_shortfall = true;
|
|
shortfall_cycle = VM_LAUNDER_RATE / VM_INACT_SCAN_RATE;
|
|
target = shortfall;
|
|
} else if (!in_shortfall)
|
|
goto trybackground;
|
|
else if (shortfall_cycle == 0 || vm_laundry_target() <= 0) {
|
|
/*
|
|
* We recently entered shortfall and began laundering
|
|
* pages. If we have completed that laundering run
|
|
* (and we are no longer in shortfall) or we have met
|
|
* our laundry target through other activity, then we
|
|
* can stop laundering pages.
|
|
*/
|
|
in_shortfall = false;
|
|
target = 0;
|
|
goto trybackground;
|
|
}
|
|
last_launder = wakeups;
|
|
launder = target / shortfall_cycle--;
|
|
goto dolaundry;
|
|
|
|
/*
|
|
* There's no immediate need to launder any pages; see if we
|
|
* meet the conditions to perform background laundering:
|
|
*
|
|
* 1. The ratio of dirty to clean inactive pages exceeds the
|
|
* background laundering threshold and the pagedaemon has
|
|
* been woken up to reclaim pages since our last
|
|
* laundering, or
|
|
* 2. we haven't yet reached the target of the current
|
|
* background laundering run.
|
|
*
|
|
* The background laundering threshold is not a constant.
|
|
* Instead, it is a slowly growing function of the number of
|
|
* page daemon wakeups since the last laundering. Thus, as the
|
|
* ratio of dirty to clean inactive pages grows, the amount of
|
|
* memory pressure required to trigger laundering decreases.
|
|
*/
|
|
trybackground:
|
|
nclean = vm_cnt.v_inactive_count + vm_cnt.v_free_count;
|
|
ndirty = vm_cnt.v_laundry_count;
|
|
if (target == 0 && wakeups != last_launder &&
|
|
ndirty * isqrt(wakeups - last_launder) >= nclean) {
|
|
target = vm_background_launder_target;
|
|
}
|
|
|
|
/*
|
|
* We have a non-zero background laundering target. If we've
|
|
* laundered up to our maximum without observing a page daemon
|
|
* wakeup, just stop. This is a safety belt that ensures we
|
|
* don't launder an excessive amount if memory pressure is low
|
|
* and the ratio of dirty to clean pages is large. Otherwise,
|
|
* proceed at the background laundering rate.
|
|
*/
|
|
if (target > 0) {
|
|
if (wakeups != last_launder) {
|
|
last_launder = wakeups;
|
|
last_target = target;
|
|
} else if (last_target - target >=
|
|
vm_background_launder_max * PAGE_SIZE / 1024) {
|
|
target = 0;
|
|
}
|
|
launder = vm_background_launder_rate * PAGE_SIZE / 1024;
|
|
launder /= VM_LAUNDER_RATE;
|
|
if (launder > target)
|
|
launder = target;
|
|
}
|
|
|
|
dolaundry:
|
|
if (launder > 0) {
|
|
/*
|
|
* Because of I/O clustering, the number of laundered
|
|
* pages could exceed "target" by the maximum size of
|
|
* a cluster minus one.
|
|
*/
|
|
target -= min(vm_pageout_launder(domain, launder,
|
|
in_shortfall), target);
|
|
pause("laundp", hz / VM_LAUNDER_RATE);
|
|
}
|
|
|
|
/*
|
|
* If we're not currently laundering pages and the page daemon
|
|
* hasn't posted a new request, sleep until the page daemon
|
|
* kicks us.
|
|
*/
|
|
vm_pagequeue_lock(pq);
|
|
if (target == 0 && vm_laundry_request == VM_LAUNDRY_IDLE)
|
|
(void)mtx_sleep(&vm_laundry_request,
|
|
vm_pagequeue_lockptr(pq), PVM, "launds", 0);
|
|
|
|
/*
|
|
* If the pagedaemon has indicated that it's in shortfall, start
|
|
* a shortfall laundering unless we're already in the middle of
|
|
* one. This may preempt a background laundering.
|
|
*/
|
|
if (vm_laundry_request == VM_LAUNDRY_SHORTFALL &&
|
|
(!in_shortfall || shortfall_cycle == 0)) {
|
|
shortfall = vm_laundry_target() + vm_pageout_deficit;
|
|
target = 0;
|
|
} else
|
|
shortfall = 0;
|
|
|
|
if (target == 0)
|
|
vm_laundry_request = VM_LAUNDRY_IDLE;
|
|
vm_pagequeue_unlock(pq);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* vm_pageout_scan does the dirty work for the pageout daemon.
|
|
*
|
|
* pass == 0: Update active LRU/deactivate pages
|
|
* pass >= 1: Free inactive pages
|
|
*
|
|
* Returns true if pass was zero or enough pages were freed by the inactive
|
|
* queue scan to meet the target.
|
|
*/
|
|
static bool
|
|
vm_pageout_scan(struct vm_domain *vmd, int pass)
|
|
{
|
|
vm_page_t m, next;
|
|
struct vm_pagequeue *pq;
|
|
vm_object_t object;
|
|
long min_scan;
|
|
int act_delta, addl_page_shortage, deficit, inactq_shortage, maxscan;
|
|
int page_shortage, scan_tick, scanned, starting_page_shortage;
|
|
boolean_t queue_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 &&
|
|
(time_uptime - lowmem_uptime) >= lowmem_period) {
|
|
/*
|
|
* Decrease registered cache sizes.
|
|
*/
|
|
SDT_PROBE0(vm, , , vm__lowmem_scan);
|
|
EVENTHANDLER_INVOKE(vm_lowmem, 0);
|
|
/*
|
|
* We do this explicitly after the caches have been
|
|
* drained above.
|
|
*/
|
|
uma_reclaim();
|
|
lowmem_uptime = time_uptime;
|
|
}
|
|
|
|
/*
|
|
* 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;
|
|
|
|
/*
|
|
* Calculate the number of pages that we want to free. This number
|
|
* can be negative if many pages are freed between the wakeup call to
|
|
* the page daemon and this calculation.
|
|
*/
|
|
if (pass > 0) {
|
|
deficit = atomic_readandclear_int(&vm_pageout_deficit);
|
|
page_shortage = vm_paging_target() + deficit;
|
|
} else
|
|
page_shortage = deficit = 0;
|
|
starting_page_shortage = page_shortage;
|
|
|
|
/*
|
|
* Start scanning the inactive queue for pages that we can free. The
|
|
* scan will stop when we reach the target or we have scanned the
|
|
* entire queue. (Note that m->act_count is not used to make
|
|
* decisions for the inactive queue, only for the active queue.)
|
|
*/
|
|
pq = &vmd->vmd_pagequeues[PQ_INACTIVE];
|
|
maxscan = pq->pq_cnt;
|
|
vm_pagequeue_lock(pq);
|
|
queue_locked = TRUE;
|
|
for (m = TAILQ_FIRST(&pq->pq_pl);
|
|
m != NULL && maxscan-- > 0 && page_shortage > 0;
|
|
m = next) {
|
|
vm_pagequeue_assert_locked(pq);
|
|
KASSERT(queue_locked, ("unlocked inactive queue"));
|
|
KASSERT(vm_page_inactive(m), ("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))
|
|
goto unlock_page;
|
|
else if (m->hold_count != 0) {
|
|
/*
|
|
* Held pages are essentially stuck in the
|
|
* queue. So, they ought to be discounted
|
|
* from the inactive count. See the
|
|
* calculation of inactq_shortage before the
|
|
* loop over the active queue below.
|
|
*/
|
|
addl_page_shortage++;
|
|
goto unlock_page;
|
|
}
|
|
object = m->object;
|
|
if (!VM_OBJECT_TRYWLOCK(object)) {
|
|
if (!vm_pageout_fallback_object_lock(m, &next))
|
|
goto unlock_object;
|
|
else if (m->hold_count != 0) {
|
|
addl_page_shortage++;
|
|
goto unlock_object;
|
|
}
|
|
}
|
|
if (vm_page_busied(m)) {
|
|
/*
|
|
* Don't mess with busy pages. Leave them at
|
|
* the front of the queue. Most likely, they
|
|
* are being paged out and will leave the
|
|
* queue shortly after the scan finishes. So,
|
|
* they ought to be discounted from the
|
|
* inactive count.
|
|
*/
|
|
addl_page_shortage++;
|
|
unlock_object:
|
|
VM_OBJECT_WUNLOCK(object);
|
|
unlock_page:
|
|
vm_page_unlock(m);
|
|
continue;
|
|
}
|
|
KASSERT(m->hold_count == 0, ("Held page %p", m));
|
|
|
|
/*
|
|
* Dequeue the inactive page and unlock the inactive page
|
|
* queue, invalidating the 'next' pointer. Dequeueing the
|
|
* page here avoids a later reacquisition (and release) of
|
|
* the inactive page queue lock when vm_page_activate(),
|
|
* vm_page_free(), or vm_page_launder() is called. Use a
|
|
* marker to remember our place in the inactive queue.
|
|
*/
|
|
TAILQ_INSERT_AFTER(&pq->pq_pl, m, &vmd->vmd_marker, plinks.q);
|
|
vm_page_dequeue_locked(m);
|
|
vm_pagequeue_unlock(pq);
|
|
queue_locked = FALSE;
|
|
|
|
/*
|
|
* Invalid pages can be easily freed. They cannot be
|
|
* mapped, vm_page_free() asserts this.
|
|
*/
|
|
if (m->valid == 0)
|
|
goto free_page;
|
|
|
|
/*
|
|
* If the page has been referenced and the object is not dead,
|
|
* reactivate or requeue the page depending on whether the
|
|
* object is mapped.
|
|
*/
|
|
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 (act_delta != 0) {
|
|
if (object->ref_count != 0) {
|
|
PCPU_INC(cnt.v_reactivated);
|
|
vm_page_activate(m);
|
|
|
|
/*
|
|
* Increase the activation count if the page
|
|
* was referenced while in the inactive queue.
|
|
* This makes it less likely that the page will
|
|
* be returned prematurely to the inactive
|
|
* queue.
|
|
*/
|
|
m->act_count += act_delta + ACT_ADVANCE;
|
|
goto drop_page;
|
|
} else if ((object->flags & OBJ_DEAD) == 0) {
|
|
vm_pagequeue_lock(pq);
|
|
queue_locked = TRUE;
|
|
m->queue = PQ_INACTIVE;
|
|
TAILQ_INSERT_TAIL(&pq->pq_pl, m, plinks.q);
|
|
vm_pagequeue_cnt_inc(pq);
|
|
goto drop_page;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* If the page appears to be clean at the machine-independent
|
|
* layer, then remove all of its mappings from the pmap in
|
|
* anticipation of freeing it. If, however, any of the page's
|
|
* mappings allow write access, then the page may still be
|
|
* modified until the last of those mappings are removed.
|
|
*/
|
|
if (object->ref_count != 0) {
|
|
vm_page_test_dirty(m);
|
|
if (m->dirty == 0)
|
|
pmap_remove_all(m);
|
|
}
|
|
|
|
/*
|
|
* Clean pages can be freed, but dirty pages must be sent back
|
|
* to the laundry, unless they belong to a dead object.
|
|
* Requeueing dirty pages from dead objects is pointless, as
|
|
* they are being paged out and freed by the thread that
|
|
* destroyed the object.
|
|
*/
|
|
if (m->dirty == 0) {
|
|
free_page:
|
|
vm_page_free(m);
|
|
PCPU_INC(cnt.v_dfree);
|
|
--page_shortage;
|
|
} else if ((object->flags & OBJ_DEAD) == 0)
|
|
vm_page_launder(m);
|
|
drop_page:
|
|
vm_page_unlock(m);
|
|
VM_OBJECT_WUNLOCK(object);
|
|
if (!queue_locked) {
|
|
vm_pagequeue_lock(pq);
|
|
queue_locked = TRUE;
|
|
}
|
|
next = TAILQ_NEXT(&vmd->vmd_marker, plinks.q);
|
|
TAILQ_REMOVE(&pq->pq_pl, &vmd->vmd_marker, plinks.q);
|
|
}
|
|
vm_pagequeue_unlock(pq);
|
|
|
|
/*
|
|
* Wake up the laundry thread so that it can perform any needed
|
|
* laundering. If we didn't meet our target, we're in shortfall and
|
|
* need to launder more aggressively.
|
|
*/
|
|
if (vm_laundry_request == VM_LAUNDRY_IDLE &&
|
|
starting_page_shortage > 0) {
|
|
pq = &vm_dom[0].vmd_pagequeues[PQ_LAUNDRY];
|
|
vm_pagequeue_lock(pq);
|
|
if (page_shortage > 0) {
|
|
vm_laundry_request = VM_LAUNDRY_SHORTFALL;
|
|
PCPU_INC(cnt.v_pdshortfalls);
|
|
} else if (vm_laundry_request != VM_LAUNDRY_SHORTFALL)
|
|
vm_laundry_request = VM_LAUNDRY_BACKGROUND;
|
|
wakeup(&vm_laundry_request);
|
|
vm_pagequeue_unlock(pq);
|
|
}
|
|
|
|
#if !defined(NO_SWAPPING)
|
|
/*
|
|
* Wakeup the swapout daemon if we didn't free the targeted number of
|
|
* pages.
|
|
*/
|
|
if (vm_swap_enabled && page_shortage > 0)
|
|
vm_req_vmdaemon(VM_SWAP_NORMAL);
|
|
#endif
|
|
|
|
/*
|
|
* If the inactive queue scan fails repeatedly to meet its
|
|
* target, kill the largest process.
|
|
*/
|
|
vm_pageout_mightbe_oom(vmd, page_shortage, starting_page_shortage);
|
|
|
|
/*
|
|
* Compute the number of pages we want to try to move from the
|
|
* active queue to either the inactive or laundry queue.
|
|
*
|
|
* When scanning active pages, we make clean pages count more heavily
|
|
* towards the page shortage than dirty pages. This is because dirty
|
|
* pages must be laundered before they can be reused and thus have less
|
|
* utility when attempting to quickly alleviate a shortage. However,
|
|
* this weighting also causes the scan to deactivate dirty pages more
|
|
* more aggressively, improving the effectiveness of clustering and
|
|
* ensuring that they can eventually be reused.
|
|
*/
|
|
inactq_shortage = vm_cnt.v_inactive_target - (vm_cnt.v_inactive_count +
|
|
vm_cnt.v_laundry_count / act_scan_laundry_weight) +
|
|
vm_paging_target() + deficit + addl_page_shortage;
|
|
page_shortage *= act_scan_laundry_weight;
|
|
|
|
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.
|
|
*/
|
|
scan_tick = ticks;
|
|
if (vm_pageout_update_period != 0) {
|
|
min_scan = pq->pq_cnt;
|
|
min_scan *= scan_tick - vmd->vmd_last_active_scan;
|
|
min_scan /= hz * vm_pageout_update_period;
|
|
} else
|
|
min_scan = 0;
|
|
if (min_scan > 0 || (inactq_shortage > 0 && maxscan > 0))
|
|
vmd->vmd_last_active_scan = scan_tick;
|
|
|
|
/*
|
|
* Scan the active queue for pages that can be deactivated. Update
|
|
* the per-page activity counter and use it to identify deactivation
|
|
* candidates. Held pages may be deactivated.
|
|
*/
|
|
for (m = TAILQ_FIRST(&pq->pq_pl), scanned = 0; m != NULL && (scanned <
|
|
min_scan || (inactq_shortage > 0 && scanned < maxscan)); m = next,
|
|
scanned++) {
|
|
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)
|
|
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);
|
|
continue;
|
|
}
|
|
|
|
/*
|
|
* The count for page daemon pages is updated 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;
|
|
|
|
/*
|
|
* Perform an unsynchronized object ref count check. While
|
|
* the page lock ensures that the page is not reallocated to
|
|
* another object, in particular, one with unmanaged mappings
|
|
* that cannot support pmap_ts_referenced(), two races are,
|
|
* nonetheless, possible:
|
|
* 1) The count was transitioning to zero, but we saw a non-
|
|
* zero value. pmap_ts_referenced() will return zero
|
|
* because the page is not mapped.
|
|
* 2) The count was transitioning to one, but we saw zero.
|
|
* This race delays the detection of a new reference. At
|
|
* worst, we will deactivate and reactivate the page.
|
|
*/
|
|
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, inactive or laundry
|
|
* queue depending on usage.
|
|
*/
|
|
if (m->act_count == 0) {
|
|
/* Dequeue to avoid later lock recursion. */
|
|
vm_page_dequeue_locked(m);
|
|
|
|
/*
|
|
* When not short for inactive pages, let dirty pages go
|
|
* through the inactive queue before moving to the
|
|
* laundry queues. This gives them some extra time to
|
|
* be reactivated, potentially avoiding an expensive
|
|
* pageout. During a page shortage, the inactive queue
|
|
* is necessarily small, so we may move dirty pages
|
|
* directly to the laundry queue.
|
|
*/
|
|
if (inactq_shortage <= 0)
|
|
vm_page_deactivate(m);
|
|
else {
|
|
/*
|
|
* Calling vm_page_test_dirty() here would
|
|
* require acquisition of the object's write
|
|
* lock. However, during a page shortage,
|
|
* directing dirty pages into the laundry
|
|
* queue is only an optimization and not a
|
|
* requirement. Therefore, we simply rely on
|
|
* the opportunistic updates to the page's
|
|
* dirty field by the pmap.
|
|
*/
|
|
if (m->dirty == 0) {
|
|
vm_page_deactivate(m);
|
|
inactq_shortage -=
|
|
act_scan_laundry_weight;
|
|
} else {
|
|
vm_page_launder(m);
|
|
inactq_shortage--;
|
|
}
|
|
}
|
|
} else
|
|
vm_page_requeue_locked(m);
|
|
vm_page_unlock(m);
|
|
}
|
|
vm_pagequeue_unlock(pq);
|
|
#if !defined(NO_SWAPPING)
|
|
/*
|
|
* Idle process swapout -- run once per second when we are reclaiming
|
|
* pages.
|
|
*/
|
|
if (vm_swap_idle_enabled && pass > 0) {
|
|
static long lsec;
|
|
if (time_second != lsec) {
|
|
vm_req_vmdaemon(VM_SWAP_IDLE);
|
|
lsec = time_second;
|
|
}
|
|
}
|
|
#endif
|
|
return (page_shortage <= 0);
|
|
}
|
|
|
|
static int vm_pageout_oom_vote;
|
|
|
|
/*
|
|
* The pagedaemon threads randlomly select one to perform the
|
|
* OOM. Trying to kill processes before all pagedaemons
|
|
* failed to reach free target is premature.
|
|
*/
|
|
static void
|
|
vm_pageout_mightbe_oom(struct vm_domain *vmd, int page_shortage,
|
|
int starting_page_shortage)
|
|
{
|
|
int old_vote;
|
|
|
|
if (starting_page_shortage <= 0 || starting_page_shortage !=
|
|
page_shortage)
|
|
vmd->vmd_oom_seq = 0;
|
|
else
|
|
vmd->vmd_oom_seq++;
|
|
if (vmd->vmd_oom_seq < vm_pageout_oom_seq) {
|
|
if (vmd->vmd_oom) {
|
|
vmd->vmd_oom = FALSE;
|
|
atomic_subtract_int(&vm_pageout_oom_vote, 1);
|
|
}
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* Do not follow the call sequence until OOM condition is
|
|
* cleared.
|
|
*/
|
|
vmd->vmd_oom_seq = 0;
|
|
|
|
if (vmd->vmd_oom)
|
|
return;
|
|
|
|
vmd->vmd_oom = TRUE;
|
|
old_vote = atomic_fetchadd_int(&vm_pageout_oom_vote, 1);
|
|
if (old_vote != vm_ndomains - 1)
|
|
return;
|
|
|
|
/*
|
|
* The current pagedaemon thread is the last in the quorum to
|
|
* start OOM. Initiate the selection and signaling of the
|
|
* victim.
|
|
*/
|
|
vm_pageout_oom(VM_OOM_MEM);
|
|
|
|
/*
|
|
* After one round of OOM terror, recall our vote. On the
|
|
* next pass, current pagedaemon would vote again if the low
|
|
* memory condition is still there, due to vmd_oom being
|
|
* false.
|
|
*/
|
|
vmd->vmd_oom = FALSE;
|
|
atomic_subtract_int(&vm_pageout_oom_vote, 1);
|
|
}
|
|
|
|
/*
|
|
* The OOM killer is the page daemon's action of last resort when
|
|
* memory allocation requests have been stalled for a prolonged period
|
|
* of time because it cannot reclaim memory. This function computes
|
|
* the approximate number of physical pages that could be reclaimed if
|
|
* the specified address space is destroyed.
|
|
*
|
|
* Private, anonymous memory owned by the address space is the
|
|
* principal resource that we expect to recover after an OOM kill.
|
|
* Since the physical pages mapped by the address space's COW entries
|
|
* are typically shared pages, they are unlikely to be released and so
|
|
* they are not counted.
|
|
*
|
|
* To get to the point where the page daemon runs the OOM killer, its
|
|
* efforts to write-back vnode-backed pages may have stalled. This
|
|
* could be caused by a memory allocation deadlock in the write path
|
|
* that might be resolved by an OOM kill. Therefore, physical pages
|
|
* belonging to vnode-backed objects are counted, because they might
|
|
* be freed without being written out first if the address space holds
|
|
* the last reference to an unlinked vnode.
|
|
*
|
|
* Similarly, physical pages belonging to OBJT_PHYS objects are
|
|
* counted because the address space might hold the last reference to
|
|
* the object.
|
|
*/
|
|
static long
|
|
vm_pageout_oom_pagecount(struct vmspace *vmspace)
|
|
{
|
|
vm_map_t map;
|
|
vm_map_entry_t entry;
|
|
vm_object_t obj;
|
|
long res;
|
|
|
|
map = &vmspace->vm_map;
|
|
KASSERT(!map->system_map, ("system map"));
|
|
sx_assert(&map->lock, SA_LOCKED);
|
|
res = 0;
|
|
for (entry = map->header.next; entry != &map->header;
|
|
entry = entry->next) {
|
|
if ((entry->eflags & MAP_ENTRY_IS_SUB_MAP) != 0)
|
|
continue;
|
|
obj = entry->object.vm_object;
|
|
if (obj == NULL)
|
|
continue;
|
|
if ((entry->eflags & MAP_ENTRY_NEEDS_COPY) != 0 &&
|
|
obj->ref_count != 1)
|
|
continue;
|
|
switch (obj->type) {
|
|
case OBJT_DEFAULT:
|
|
case OBJT_SWAP:
|
|
case OBJT_PHYS:
|
|
case OBJT_VNODE:
|
|
res += obj->resident_page_count;
|
|
break;
|
|
}
|
|
}
|
|
return (res);
|
|
}
|
|
|
|
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 its child processes
|
|
* attempts to propagate a signal to B while we are waiting for A's
|
|
* lock while walking this list. To avoid this, we don't block on
|
|
* the process lock but just skip a process if it is already locked.
|
|
*/
|
|
bigproc = NULL;
|
|
bigsize = 0;
|
|
sx_slock(&allproc_lock);
|
|
FOREACH_PROC_IN_SYSTEM(p) {
|
|
int breakout;
|
|
|
|
PROC_LOCK(p);
|
|
|
|
/*
|
|
* If this is a system, protected or killed process, skip it.
|
|
*/
|
|
if (p->p_state != PRS_NORMAL || (p->p_flag & (P_INEXEC |
|
|
P_PROTECTED | P_SYSTEM | P_WEXIT)) != 0 ||
|
|
p->p_pid == 1 || P_KILLED(p) ||
|
|
(p->p_pid < 48 && swap_pager_avail != 0)) {
|
|
PROC_UNLOCK(p);
|
|
continue;
|
|
}
|
|
/*
|
|
* If the process is in a non-running type state,
|
|
* don't touch it. Check all the threads individually.
|
|
*/
|
|
breakout = 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) &&
|
|
!TD_IS_SWAPPED(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;
|
|
}
|
|
_PHOLD_LITE(p);
|
|
PROC_UNLOCK(p);
|
|
sx_sunlock(&allproc_lock);
|
|
if (!vm_map_trylock_read(&vm->vm_map)) {
|
|
vmspace_free(vm);
|
|
sx_slock(&allproc_lock);
|
|
PRELE(p);
|
|
continue;
|
|
}
|
|
size = vmspace_swap_count(vm);
|
|
if (shortage == VM_OOM_MEM)
|
|
size += vm_pageout_oom_pagecount(vm);
|
|
vm_map_unlock_read(&vm->vm_map);
|
|
vmspace_free(vm);
|
|
sx_slock(&allproc_lock);
|
|
|
|
/*
|
|
* If this process is bigger than the biggest one,
|
|
* remember it.
|
|
*/
|
|
if (size > bigsize) {
|
|
if (bigproc != NULL)
|
|
PRELE(bigproc);
|
|
bigproc = p;
|
|
bigsize = size;
|
|
} else {
|
|
PRELE(p);
|
|
}
|
|
}
|
|
sx_sunlock(&allproc_lock);
|
|
if (bigproc != NULL) {
|
|
if (vm_panic_on_oom != 0)
|
|
panic("out of swap space");
|
|
PROC_LOCK(bigproc);
|
|
killproc(bigproc, "out of swap space");
|
|
sched_nice(bigproc, PRIO_MIN);
|
|
_PRELE(bigproc);
|
|
PROC_UNLOCK(bigproc);
|
|
wakeup(&vm_cnt.v_free_count);
|
|
}
|
|
}
|
|
|
|
static void
|
|
vm_pageout_worker(void *arg)
|
|
{
|
|
struct vm_domain *domain;
|
|
int domidx, pass;
|
|
bool target_met;
|
|
|
|
domidx = (uintptr_t)arg;
|
|
domain = &vm_dom[domidx];
|
|
pass = 0;
|
|
target_met = true;
|
|
|
|
/*
|
|
* XXXKIB It could be useful to bind pageout daemon threads to
|
|
* the cores belonging to the domain, from which vm_page_array
|
|
* is allocated.
|
|
*/
|
|
|
|
KASSERT(domain->vmd_segs != 0, ("domain without segments"));
|
|
domain->vmd_last_active_scan = ticks;
|
|
vm_pageout_init_marker(&domain->vmd_marker, PQ_INACTIVE);
|
|
vm_pageout_init_marker(&domain->vmd_inacthead, PQ_INACTIVE);
|
|
TAILQ_INSERT_HEAD(&domain->vmd_pagequeues[PQ_INACTIVE].pq_pl,
|
|
&domain->vmd_inacthead, plinks.q);
|
|
|
|
/*
|
|
* The pageout daemon worker is never done, so loop forever.
|
|
*/
|
|
while (TRUE) {
|
|
mtx_lock(&vm_page_queue_free_mtx);
|
|
|
|
/*
|
|
* Generally, after a level >= 1 scan, if there are enough
|
|
* free pages to wakeup the waiters, then they are already
|
|
* awake. A call to vm_page_free() during the scan awakened
|
|
* them. However, in the following case, this wakeup serves
|
|
* to bound the amount of time that a thread might wait.
|
|
* Suppose a thread's call to vm_page_alloc() fails, but
|
|
* before that thread calls VM_WAIT, enough pages are freed by
|
|
* other threads to alleviate the free page shortage. The
|
|
* thread will, nonetheless, wait until another page is freed
|
|
* or this wakeup is performed.
|
|
*/
|
|
if (vm_pages_needed && !vm_page_count_min()) {
|
|
vm_pages_needed = false;
|
|
wakeup(&vm_cnt.v_free_count);
|
|
}
|
|
|
|
/*
|
|
* Do not clear vm_pageout_wanted until we reach our free page
|
|
* target. Otherwise, we may be awakened over and over again,
|
|
* wasting CPU time.
|
|
*/
|
|
if (vm_pageout_wanted && target_met)
|
|
vm_pageout_wanted = false;
|
|
|
|
/*
|
|
* Might the page daemon receive a wakeup call?
|
|
*/
|
|
if (vm_pageout_wanted) {
|
|
/*
|
|
* No. Either vm_pageout_wanted was set by another
|
|
* thread during the previous scan, which must have
|
|
* been a level 0 scan, or vm_pageout_wanted was
|
|
* already set and the scan failed to free enough
|
|
* pages. If we haven't yet performed a level >= 1
|
|
* (page reclamation) scan, then increase the level
|
|
* and scan again now. Otherwise, sleep a bit and
|
|
* try again later.
|
|
*/
|
|
mtx_unlock(&vm_page_queue_free_mtx);
|
|
if (pass >= 1)
|
|
pause("psleep", hz / VM_INACT_SCAN_RATE);
|
|
pass++;
|
|
} else {
|
|
/*
|
|
* Yes. Sleep until pages need to be reclaimed or
|
|
* have their reference stats updated.
|
|
*/
|
|
if (mtx_sleep(&vm_pageout_wanted,
|
|
&vm_page_queue_free_mtx, PDROP | PVM, "psleep",
|
|
hz) == 0) {
|
|
PCPU_INC(cnt.v_pdwakeups);
|
|
pass = 1;
|
|
} else
|
|
pass = 0;
|
|
}
|
|
|
|
target_met = vm_pageout_scan(domain, pass);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* vm_pageout_init initialises basic pageout daemon settings.
|
|
*/
|
|
static void
|
|
vm_pageout_init(void)
|
|
{
|
|
/*
|
|
* 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;
|
|
|
|
/*
|
|
* Target amount of memory to move out of the laundry queue during a
|
|
* background laundering. This is proportional to the amount of system
|
|
* memory.
|
|
*/
|
|
vm_background_launder_target = (vm_cnt.v_free_target -
|
|
vm_cnt.v_free_min) / 10;
|
|
}
|
|
|
|
/*
|
|
* vm_pageout is the high level pageout daemon.
|
|
*/
|
|
static void
|
|
vm_pageout(void)
|
|
{
|
|
int error;
|
|
#ifdef VM_NUMA_ALLOC
|
|
int i;
|
|
#endif
|
|
|
|
swap_pager_swap_init();
|
|
error = kthread_add(vm_pageout_laundry_worker, NULL, curproc, NULL,
|
|
0, 0, "laundry: dom0");
|
|
if (error != 0)
|
|
panic("starting laundry for domain 0, error %d", error);
|
|
#ifdef VM_NUMA_ALLOC
|
|
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
|
|
error = kthread_add(uma_reclaim_worker, NULL, curproc, NULL,
|
|
0, 0, "uma");
|
|
if (error != 0)
|
|
panic("starting uma_reclaim helper, error %d\n", error);
|
|
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_pageout_wanted && curthread->td_proc != pageproc) {
|
|
vm_pageout_wanted = true;
|
|
wakeup(&vm_pageout_wanted);
|
|
}
|
|
}
|
|
|
|
#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);
|
|
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)
|
|
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_pageout_map_deactivate_pages(
|
|
&vm->vm_map, limit);
|
|
}
|
|
#ifdef RACCT
|
|
if (racct_enable) {
|
|
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_slock(&allproc_lock);
|
|
PRELE(p);
|
|
}
|
|
sx_sunlock(&allproc_lock);
|
|
if (tryagain != 0 && attempts <= 10)
|
|
goto again;
|
|
}
|
|
}
|
|
#endif /* !defined(NO_SWAPPING) */
|