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NetBSD/sys/uvm/uvm_pdaemon.c

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/* $NetBSD: uvm_pdaemon.c,v 1.26 2000/12/13 17:03:32 chs Exp $ */
/*
* Copyright (c) 1997 Charles D. Cranor and Washington University.
* Copyright (c) 1991, 1993, The Regents of the University of California.
*
* 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 Charles D. Cranor,
* Washington University, 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
* 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
* 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.
*
* @(#)vm_pageout.c 8.5 (Berkeley) 2/14/94
* from: Id: uvm_pdaemon.c,v 1.1.2.32 1998/02/06 05:26:30 chs Exp
*
*
* Copyright (c) 1987, 1990 Carnegie-Mellon University.
* All rights reserved.
*
* 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
*
* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
* School of Computer Science
* Carnegie Mellon University
* Pittsburgh PA 15213-3890
*
* any improvements or extensions that they make and grant Carnegie the
* rights to redistribute these changes.
*/
#include "opt_uvmhist.h"
/*
* uvm_pdaemon.c: the page daemon
*/
#include <sys/param.h>
#include <sys/proc.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/pool.h>
#include <sys/buf.h>
#include <uvm/uvm.h>
extern struct uvm_pagerops uvm_vnodeops;
/*
* UVMPD_NUMDIRTYREACTS is how many dirty pages the pagedeamon will reactivate
* in a pass thru the inactive list when swap is full. the value should be
* "small"... if it's too large we'll cycle the active pages thru the inactive
* queue too quickly to for them to be referenced and avoid being freed.
*/
#define UVMPD_NUMDIRTYREACTS 16
/*
* local prototypes
*/
static void uvmpd_scan __P((void));
static boolean_t uvmpd_scan_inactive __P((struct pglist *));
static void uvmpd_tune __P((void));
/*
* uvm_wait: wait (sleep) for the page daemon to free some pages
*
* => should be called with all locks released
* => should _not_ be called by the page daemon (to avoid deadlock)
*/
void
uvm_wait(wmsg)
const char *wmsg;
{
int timo = 0;
int s = splbio();
/*
* check for page daemon going to sleep (waiting for itself)
*/
if (curproc == uvm.pagedaemon_proc) {
/*
* now we have a problem: the pagedaemon wants to go to
* sleep until it frees more memory. but how can it
* free more memory if it is asleep? that is a deadlock.
* we have two options:
* [1] panic now
* [2] put a timeout on the sleep, thus causing the
* pagedaemon to only pause (rather than sleep forever)
*
* note that option [2] will only help us if we get lucky
* and some other process on the system breaks the deadlock
* by exiting or freeing memory (thus allowing the pagedaemon
* to continue). for now we panic if DEBUG is defined,
* otherwise we hope for the best with option [2] (better
* yet, this should never happen in the first place!).
*/
printf("pagedaemon: deadlock detected!\n");
timo = hz >> 3; /* set timeout */
#if defined(DEBUG)
/* DEBUG: panic so we can debug it */
panic("pagedaemon deadlock");
#endif
}
simple_lock(&uvm.pagedaemon_lock);
wakeup(&uvm.pagedaemon); /* wake the daemon! */
UVM_UNLOCK_AND_WAIT(&uvmexp.free, &uvm.pagedaemon_lock, FALSE, wmsg,
timo);
splx(s);
}
/*
* uvmpd_tune: tune paging parameters
*
* => called when ever memory is added (or removed?) to the system
* => caller must call with page queues locked
*/
static void
uvmpd_tune()
{
UVMHIST_FUNC("uvmpd_tune"); UVMHIST_CALLED(pdhist);
uvmexp.freemin = uvmexp.npages / 20;
/* between 16k and 256k */
/* XXX: what are these values good for? */
uvmexp.freemin = max(uvmexp.freemin, (16*1024) >> PAGE_SHIFT);
uvmexp.freemin = min(uvmexp.freemin, (256*1024) >> PAGE_SHIFT);
/* Make sure there's always a user page free. */
if (uvmexp.freemin < uvmexp.reserve_kernel + 1)
uvmexp.freemin = uvmexp.reserve_kernel + 1;
uvmexp.freetarg = (uvmexp.freemin * 4) / 3;
if (uvmexp.freetarg <= uvmexp.freemin)
uvmexp.freetarg = uvmexp.freemin + 1;
/* uvmexp.inactarg: computed in main daemon loop */
uvmexp.wiredmax = uvmexp.npages / 3;
UVMHIST_LOG(pdhist, "<- done, freemin=%d, freetarg=%d, wiredmax=%d",
uvmexp.freemin, uvmexp.freetarg, uvmexp.wiredmax, 0);
}
/*
* uvm_pageout: the main loop for the pagedaemon
*/
void
uvm_pageout(void *arg)
{
int npages = 0;
UVMHIST_FUNC("uvm_pageout"); UVMHIST_CALLED(pdhist);
UVMHIST_LOG(pdhist,"<starting uvm pagedaemon>", 0, 0, 0, 0);
/*
* ensure correct priority and set paging parameters...
*/
uvm.pagedaemon_proc = curproc;
(void) spl0();
uvm_lock_pageq();
npages = uvmexp.npages;
uvmpd_tune();
uvm_unlock_pageq();
/*
* main loop
*/
for (;;) {
simple_lock(&uvm.pagedaemon_lock);
UVMHIST_LOG(pdhist," <<SLEEPING>>",0,0,0,0);
UVM_UNLOCK_AND_WAIT(&uvm.pagedaemon,
&uvm.pagedaemon_lock, FALSE, "pgdaemon", 0);
uvmexp.pdwoke++;
UVMHIST_LOG(pdhist," <<WOKE UP>>",0,0,0,0);
/* drain pool resources */
pool_drain(0);
/*
* now lock page queues and recompute inactive count
*/
uvm_lock_pageq();
if (npages != uvmexp.npages) { /* check for new pages? */
npages = uvmexp.npages;
uvmpd_tune();
}
uvmexp.inactarg = (uvmexp.active + uvmexp.inactive) / 3;
if (uvmexp.inactarg <= uvmexp.freetarg) {
uvmexp.inactarg = uvmexp.freetarg + 1;
}
UVMHIST_LOG(pdhist," free/ftarg=%d/%d, inact/itarg=%d/%d",
uvmexp.free, uvmexp.freetarg, uvmexp.inactive,
uvmexp.inactarg);
/*
* scan if needed
*/
if (uvmexp.free + uvmexp.paging < uvmexp.freetarg ||
uvmexp.inactive < uvmexp.inactarg ||
uvmexp.vnodepages >
(uvmexp.active + uvmexp.inactive + uvmexp.wired +
uvmexp.free) * 13 / 16) {
uvmpd_scan();
}
/*
* if there's any free memory to be had,
* wake up any waiters.
*/
if (uvmexp.free > uvmexp.reserve_kernel ||
uvmexp.paging == 0) {
wakeup(&uvmexp.free);
}
/*
* scan done. unlock page queues (the only lock we are holding)
*/
uvm_unlock_pageq();
}
/*NOTREACHED*/
}
/*
* uvm_aiodone_daemon: main loop for the aiodone daemon.
*/
void
uvm_aiodone_daemon(void *arg)
{
int s, free;
struct buf *bp, *nbp;
UVMHIST_FUNC("uvm_aiodoned"); UVMHIST_CALLED(pdhist);
for (;;) {
/*
* carefully attempt to go to sleep (without losing "wakeups"!).
* we need splbio because we want to make sure the aio_done list
* is totally empty before we go to sleep.
*/
s = splbio();
simple_lock(&uvm.aiodoned_lock);
if (TAILQ_FIRST(&uvm.aio_done) == NULL) {
UVMHIST_LOG(pdhist," <<SLEEPING>>",0,0,0,0);
UVM_UNLOCK_AND_WAIT(&uvm.aiodoned,
&uvm.aiodoned_lock, FALSE, "aiodoned", 0);
UVMHIST_LOG(pdhist," <<WOKE UP>>",0,0,0,0);
/* relock aiodoned_lock, still at splbio */
simple_lock(&uvm.aiodoned_lock);
}
/*
* check for done aio structures
*/
bp = TAILQ_FIRST(&uvm.aio_done);
if (bp) {
TAILQ_INIT(&uvm.aio_done);
}
simple_unlock(&uvm.aiodoned_lock);
splx(s);
/*
* process each i/o that's done.
*/
free = uvmexp.free;
while (bp != NULL) {
if (bp->b_flags & B_PDAEMON) {
uvmexp.paging -= bp->b_bufsize >> PAGE_SHIFT;
}
nbp = TAILQ_NEXT(bp, b_freelist);
(*bp->b_iodone)(bp);
bp = nbp;
}
if (free <= uvmexp.reserve_kernel) {
s = uvm_lock_fpageq();
wakeup(&uvm.pagedaemon);
uvm_unlock_fpageq(s);
} else {
simple_lock(&uvm.pagedaemon_lock);
wakeup(&uvmexp.free);
simple_unlock(&uvm.pagedaemon_lock);
}
}
}
/*
* uvmpd_scan_inactive: scan an inactive list for pages to clean or free.
*
* => called with page queues locked
* => we work on meeting our free target by converting inactive pages
* into free pages.
* => we handle the building of swap-backed clusters
* => we return TRUE if we are exiting because we met our target
*/
static boolean_t
uvmpd_scan_inactive(pglst)
struct pglist *pglst;
{
boolean_t retval = FALSE; /* assume we haven't hit target */
int s, free, result;
struct vm_page *p, *nextpg;
struct uvm_object *uobj;
struct vm_page *pps[MAXBSIZE >> PAGE_SHIFT], **ppsp;
int npages;
struct vm_page *swpps[MAXBSIZE >> PAGE_SHIFT]; /* XXX: see below */
int swnpages, swcpages; /* XXX: see below */
int swslot;
struct vm_anon *anon;
boolean_t swap_backed, vnode_only;
vaddr_t start;
int dirtyreacts, vpgs;
UVMHIST_FUNC("uvmpd_scan_inactive"); UVMHIST_CALLED(pdhist);
/*
* note: we currently keep swap-backed pages on a seperate inactive
* list from object-backed pages. however, merging the two lists
* back together again hasn't been ruled out. thus, we keep our
* swap cluster in "swpps" rather than in pps (allows us to mix
* clustering types in the event of a mixed inactive queue).
*/
/*
* swslot is non-zero if we are building a swap cluster. we want
* to stay in the loop while we have a page to scan or we have
* a swap-cluster to build.
*/
swslot = 0;
swnpages = swcpages = 0;
free = 0;
dirtyreacts = 0;
vnode_only = FALSE;
for (p = TAILQ_FIRST(pglst); p != NULL || swslot != 0; p = nextpg) {
/*
* note that p can be NULL iff we have traversed the whole
* list and need to do one final swap-backed clustered pageout.
*/
uobj = NULL;
anon = NULL;
if (p) {
/*
* update our copy of "free" and see if we've met
* our target
*/
s = uvm_lock_fpageq();
free = uvmexp.free;
uvm_unlock_fpageq(s);
/* XXXUBC */
vpgs = uvmexp.vnodepages -
(uvmexp.active + uvmexp.inactive +
uvmexp.wired + uvmexp.free) * 13 / 16;
if (free + uvmexp.paging >= uvmexp.freetarg << 2 ||
vpgs > 0 || dirtyreacts == UVMPD_NUMDIRTYREACTS) {
if (vpgs <= 0) {
UVMHIST_LOG(pdhist," met free target: "
"exit loop", 0, 0, 0, 0);
retval = TRUE;
if (swslot == 0)
/* exit now if no
swap-i/o pending */
break;
/* set p to null to signal final
swap i/o */
p = NULL;
} else {
vnode_only = TRUE;
}
}
}
if (p) { /* if (we have a new page to consider) */
/*
* we are below target and have a new page to consider.
*/
uvmexp.pdscans++;
nextpg = TAILQ_NEXT(p, pageq);
/*
* first we attempt to lock the object that this page
* belongs to. if our attempt fails we skip on to
* the next page (no harm done). it is important to
* "try" locking the object as we are locking in the
* wrong order (pageq -> object) and we don't want to
* deadlock.
*
* the only time we expect to see an ownerless page
* (i.e. a page with no uobject and !PQ_ANON) is if an
* anon has loaned a page from a uvm_object and the
* uvm_object has dropped the ownership. in that
* case, the anon can "take over" the loaned page
* and make it its own.
*/
/* is page part of an anon or ownerless ? */
if ((p->pqflags & PQ_ANON) || p->uobject == NULL) {
if (vnode_only) {
uvm_pageactivate(p);
continue;
}
anon = p->uanon;
KASSERT(anon != NULL);
if (!simple_lock_try(&anon->an_lock))
/* lock failed, skip this page */
continue;
/*
* if the page is ownerless, claim it in the
* name of "anon"!
*/
if ((p->pqflags & PQ_ANON) == 0) {
KASSERT(p->loan_count > 0);
p->loan_count--;
p->pqflags |= PQ_ANON;
/* anon now owns it */
}
if (p->flags & PG_BUSY) {
simple_unlock(&anon->an_lock);
uvmexp.pdbusy++;
/* someone else owns page, skip it */
continue;
}
uvmexp.pdanscan++;
} else {
uobj = p->uobject;
KASSERT(uobj != NULL);
if (vnode_only &&
uobj->pgops != &uvm_vnodeops) {
uvm_pageactivate(p);
continue;
}
if (!simple_lock_try(&uobj->vmobjlock))
/* lock failed, skip this page */
continue;
if (p->flags & PG_BUSY) {
simple_unlock(&uobj->vmobjlock);
uvmexp.pdbusy++;
/* someone else owns page, skip it */
continue;
}
uvmexp.pdobscan++;
}
/*
* we now have the object and the page queues locked.
* the page is not busy. if the page is clean we
* can free it now and continue.
*/
if (p->flags & PG_CLEAN) {
if (p->pqflags & PQ_SWAPBACKED) {
/* this page now lives only in swap */
simple_lock(&uvm.swap_data_lock);
uvmexp.swpgonly++;
simple_unlock(&uvm.swap_data_lock);
}
uvm_pagefree(p);
uvmexp.pdfreed++;
if (anon) {
/*
* an anonymous page can only be clean
* if it has backing store assigned.
*/
KASSERT(anon->an_swslot != 0);
/* remove from object */
anon->u.an_page = NULL;
simple_unlock(&anon->an_lock);
} else {
/* pagefree has already removed the
* page from the object */
simple_unlock(&uobj->vmobjlock);
}
continue;
}
/*
* this page is dirty, skip it if we'll have met our
* free target when all the current pageouts complete.
*/
if (free + uvmexp.paging > uvmexp.freetarg << 2 &&
!vnode_only) {
if (anon) {
simple_unlock(&anon->an_lock);
} else {
simple_unlock(&uobj->vmobjlock);
}
continue;
}
/*
* this page is dirty, but we can't page it out
* since all pages in swap are only in swap.
* reactivate it so that we eventually cycle
* all pages thru the inactive queue.
*/
KASSERT(uvmexp.swpgonly <= uvmexp.swpages);
if ((p->pqflags & PQ_SWAPBACKED) &&
uvmexp.swpgonly == uvmexp.swpages) {
dirtyreacts++;
uvm_pageactivate(p);
if (anon) {
simple_unlock(&anon->an_lock);
} else {
simple_unlock(&uobj->vmobjlock);
}
continue;
}
/*
* if the page is swap-backed and dirty and swap space
* is full, free any swap allocated to the page
* so that other pages can be paged out.
*/
KASSERT(uvmexp.swpginuse <= uvmexp.swpages);
if ((p->pqflags & PQ_SWAPBACKED) &&
uvmexp.swpginuse == uvmexp.swpages) {
if ((p->pqflags & PQ_ANON) &&
p->uanon->an_swslot) {
uvm_swap_free(p->uanon->an_swslot, 1);
p->uanon->an_swslot = 0;
}
if (p->pqflags & PQ_AOBJ) {
uao_dropswap(p->uobject,
p->offset >> PAGE_SHIFT);
}
}
/*
* the page we are looking at is dirty. we must
* clean it before it can be freed. to do this we
* first mark the page busy so that no one else will
* touch the page.
*/
swap_backed = ((p->pqflags & PQ_SWAPBACKED) != 0);
p->flags |= PG_BUSY; /* now we own it */
UVM_PAGE_OWN(p, "scan_inactive");
uvmexp.pgswapout++;
/*
* for swap-backed pages we need to (re)allocate
* swap space.
*/
if (swap_backed) {
/*
* free old swap slot (if any)
*/
if (anon) {
if (anon->an_swslot) {
uvm_swap_free(anon->an_swslot,
1);
anon->an_swslot = 0;
}
} else {
uao_dropswap(uobj,
p->offset >> PAGE_SHIFT);
}
/*
* start new cluster (if necessary)
*/
if (swslot == 0) {
swnpages = MAXBSIZE >> PAGE_SHIFT;
swslot = uvm_swap_alloc(&swnpages,
TRUE);
if (swslot == 0) {
/* no swap? give up! */
p->flags &= ~PG_BUSY;
UVM_PAGE_OWN(p, NULL);
if (anon)
simple_unlock(
&anon->an_lock);
else
simple_unlock(
&uobj->vmobjlock);
continue;
}
swcpages = 0; /* cluster is empty */
}
/*
* add block to cluster
*/
swpps[swcpages] = p;
if (anon)
anon->an_swslot = swslot + swcpages;
else
uao_set_swslot(uobj,
p->offset >> PAGE_SHIFT,
swslot + swcpages);
swcpages++;
}
} else {
/* if p == NULL we must be doing a last swap i/o */
swap_backed = TRUE;
}
/*
* now consider doing the pageout.
*
* for swap-backed pages, we do the pageout if we have either
* filled the cluster (in which case (swnpages == swcpages) or
* run out of pages (p == NULL).
*
* for object pages, we always do the pageout.
*/
if (swap_backed) {
if (p) { /* if we just added a page to cluster */
if (anon)
simple_unlock(&anon->an_lock);
else
simple_unlock(&uobj->vmobjlock);
/* cluster not full yet? */
if (swcpages < swnpages)
continue;
}
/* starting I/O now... set up for it */
npages = swcpages;
ppsp = swpps;
/* for swap-backed pages only */
start = (vaddr_t) swslot;
/* if this is final pageout we could have a few
* extra swap blocks */
if (swcpages < swnpages) {
uvm_swap_free(swslot + swcpages,
(swnpages - swcpages));
}
} else {
/* normal object pageout */
ppsp = pps;
npages = sizeof(pps) / sizeof(struct vm_page *);
/* not looked at because PGO_ALLPAGES is set */
start = 0;
}
/*
* now do the pageout.
*
* for swap_backed pages we have already built the cluster.
* for !swap_backed pages, uvm_pager_put will call the object's
* "make put cluster" function to build a cluster on our behalf.
*
* we pass the PGO_PDFREECLUST flag to uvm_pager_put to instruct
* it to free the cluster pages for us on a successful I/O (it
* always does this for un-successful I/O requests). this
* allows us to do clustered pageout without having to deal
* with cluster pages at this level.
*
* note locking semantics of uvm_pager_put with PGO_PDFREECLUST:
* IN: locked: uobj (if !swap_backed), page queues
* OUT: locked: uobj (if !swap_backed && result !=VM_PAGER_PEND)
* !locked: pageqs, uobj (if swap_backed || VM_PAGER_PEND)
*
* [the bit about VM_PAGER_PEND saves us one lock-unlock pair]
*/
/* locked: uobj (if !swap_backed), page queues */
uvmexp.pdpageouts++;
result = uvm_pager_put(swap_backed ? NULL : uobj, p,
&ppsp, &npages, PGO_ALLPAGES|PGO_PDFREECLUST, start, 0);
/* locked: uobj (if !swap_backed && result != PEND) */
/* unlocked: pageqs, object (if swap_backed ||result == PEND) */
/*
* if we did i/o to swap, zero swslot to indicate that we are
* no longer building a swap-backed cluster.
*/
if (swap_backed)
swslot = 0; /* done with this cluster */
/*
* first, we check for VM_PAGER_PEND which means that the
* async I/O is in progress and the async I/O done routine
* will clean up after us. in this case we move on to the
* next page.
*
* there is a very remote chance that the pending async i/o can
* finish _before_ we get here. if that happens, our page "p"
* may no longer be on the inactive queue. so we verify this
* when determining the next page (starting over at the head if
* we've lost our inactive page).
*/
if (result == VM_PAGER_PEND) {
uvmexp.paging += npages;
uvm_lock_pageq();
uvmexp.pdpending++;
if (p) {
if (p->pqflags & PQ_INACTIVE)
nextpg = TAILQ_NEXT(p, pageq);
else
nextpg = TAILQ_FIRST(pglst);
} else {
nextpg = NULL;
}
continue;
}
if (result == VM_PAGER_ERROR &&
curproc == uvm.pagedaemon_proc) {
uvm_lock_pageq();
nextpg = TAILQ_NEXT(p, pageq);
uvm_pageactivate(p);
continue;
}
/*
* clean up "p" if we have one
*/
if (p) {
/*
* the I/O request to "p" is done and uvm_pager_put
* has freed any cluster pages it may have allocated
* during I/O. all that is left for us to do is
* clean up page "p" (which is still PG_BUSY).
*
* our result could be one of the following:
* VM_PAGER_OK: successful pageout
*
* VM_PAGER_AGAIN: tmp resource shortage, we skip
* to next page
* VM_PAGER_{FAIL,ERROR,BAD}: an error. we
* "reactivate" page to get it out of the way (it
* will eventually drift back into the inactive
* queue for a retry).
* VM_PAGER_UNLOCK: should never see this as it is
* only valid for "get" operations
*/
/* relock p's object: page queues not lock yet, so
* no need for "try" */
/* !swap_backed case: already locked... */
if (swap_backed) {
if (anon)
simple_lock(&anon->an_lock);
else
simple_lock(&uobj->vmobjlock);
}
/* handle PG_WANTED now */
if (p->flags & PG_WANTED)
/* still holding object lock */
wakeup(p);
p->flags &= ~(PG_BUSY|PG_WANTED);
UVM_PAGE_OWN(p, NULL);
/* released during I/O? */
if (p->flags & PG_RELEASED) {
if (anon) {
/* remove page so we can get nextpg */
anon->u.an_page = NULL;
simple_unlock(&anon->an_lock);
uvm_anfree(anon); /* kills anon */
pmap_page_protect(p, VM_PROT_NONE);
anon = NULL;
uvm_lock_pageq();
nextpg = TAILQ_NEXT(p, pageq);
/* free released page */
uvm_pagefree(p);
} else {
/*
* pgo_releasepg nukes the page and
* gets "nextpg" for us. it returns
* with the page queues locked (when
* given nextpg ptr).
*/
if (!uobj->pgops->pgo_releasepg(p,
&nextpg))
/* uobj died after release */
uobj = NULL;
/*
* lock page queues here so that they're
* always locked at the end of the loop.
*/
uvm_lock_pageq();
}
} else { /* page was not released during I/O */
uvm_lock_pageq();
nextpg = TAILQ_NEXT(p, pageq);
if (result != VM_PAGER_OK) {
/* pageout was a failure... */
if (result != VM_PAGER_AGAIN)
uvm_pageactivate(p);
pmap_clear_reference(p);
/* XXXCDC: if (swap_backed) FREE p's
* swap block? */
} else {
/* pageout was a success... */
pmap_clear_reference(p);
pmap_clear_modify(p);
p->flags |= PG_CLEAN;
}
}
/*
* drop object lock (if there is an object left). do
* a safety check of nextpg to make sure it is on the
* inactive queue (it should be since PG_BUSY pages on
* the inactive queue can't be re-queued [note: not
* true for active queue]).
*/
if (anon)
simple_unlock(&anon->an_lock);
else if (uobj)
simple_unlock(&uobj->vmobjlock);
} else {
/*
* if p is null in this loop, make sure it stays null
* in the next loop.
*/
nextpg = NULL;
/*
* lock page queues here just so they're always locked
* at the end of the loop.
*/
uvm_lock_pageq();
}
if (nextpg && (nextpg->pqflags & PQ_INACTIVE) == 0) {
nextpg = TAILQ_FIRST(pglst); /* reload! */
}
}
return (retval);
}
/*
* uvmpd_scan: scan the page queues and attempt to meet our targets.
*
* => called with pageq's locked
*/
void
uvmpd_scan()
{
int s, free, inactive_shortage, swap_shortage, pages_freed;
struct vm_page *p, *nextpg;
struct uvm_object *uobj;
boolean_t got_it;
UVMHIST_FUNC("uvmpd_scan"); UVMHIST_CALLED(pdhist);
uvmexp.pdrevs++; /* counter */
uobj = NULL;
/*
* get current "free" page count
*/
s = uvm_lock_fpageq();
free = uvmexp.free;
uvm_unlock_fpageq(s);
#ifndef __SWAP_BROKEN
/*
* swap out some processes if we are below our free target.
* we need to unlock the page queues for this.
*/
if (free < uvmexp.freetarg) {
uvmexp.pdswout++;
UVMHIST_LOG(pdhist," free %d < target %d: swapout", free,
uvmexp.freetarg, 0, 0);
uvm_unlock_pageq();
uvm_swapout_threads();
uvm_lock_pageq();
}
#endif
/*
* now we want to work on meeting our targets. first we work on our
* free target by converting inactive pages into free pages. then
* we work on meeting our inactive target by converting active pages
* to inactive ones.
*/
UVMHIST_LOG(pdhist, " starting 'free' loop",0,0,0,0);
/*
* alternate starting queue between swap and object based on the
* low bit of uvmexp.pdrevs (which we bump by one each call).
*/
got_it = FALSE;
pages_freed = uvmexp.pdfreed;
if ((uvmexp.pdrevs & 1) != 0 && uvmexp.nswapdev != 0)
got_it = uvmpd_scan_inactive(&uvm.page_inactive_swp);
if (!got_it)
got_it = uvmpd_scan_inactive(&uvm.page_inactive_obj);
if (!got_it && (uvmexp.pdrevs & 1) == 0 && uvmexp.nswapdev != 0)
(void) uvmpd_scan_inactive(&uvm.page_inactive_swp);
pages_freed = uvmexp.pdfreed - pages_freed;
/*
* we have done the scan to get free pages. now we work on meeting
* our inactive target.
*/
inactive_shortage = uvmexp.inactarg - uvmexp.inactive;
/*
* detect if we're not going to be able to page anything out
* until we free some swap resources from active pages.
*/
swap_shortage = 0;
if (uvmexp.free < uvmexp.freetarg &&
uvmexp.swpginuse == uvmexp.swpages &&
uvmexp.swpgonly < uvmexp.swpages &&
pages_freed == 0) {
swap_shortage = uvmexp.freetarg - uvmexp.free;
}
UVMHIST_LOG(pdhist, " loop 2: inactive_shortage=%d swap_shortage=%d",
inactive_shortage, swap_shortage,0,0);
for (p = TAILQ_FIRST(&uvm.page_active);
p != NULL && (inactive_shortage > 0 || swap_shortage > 0);
p = nextpg) {
nextpg = TAILQ_NEXT(p, pageq);
if (p->flags & PG_BUSY)
continue; /* quick check before trying to lock */
/*
* lock the page's owner.
*/
/* is page anon owned or ownerless? */
if ((p->pqflags & PQ_ANON) || p->uobject == NULL) {
KASSERT(p->uanon != NULL);
if (!simple_lock_try(&p->uanon->an_lock))
continue;
/* take over the page? */
if ((p->pqflags & PQ_ANON) == 0) {
KASSERT(p->loan_count > 0);
p->loan_count--;
p->pqflags |= PQ_ANON;
}
} else {
if (!simple_lock_try(&p->uobject->vmobjlock))
continue;
}
/*
* skip this page if it's busy.
*/
if ((p->flags & PG_BUSY) != 0) {
if (p->pqflags & PQ_ANON)
simple_unlock(&p->uanon->an_lock);
else
simple_unlock(&p->uobject->vmobjlock);
continue;
}
/*
* if there's a shortage of swap, free any swap allocated
* to this page so that other pages can be paged out.
*/
if (swap_shortage > 0) {
if ((p->pqflags & PQ_ANON) && p->uanon->an_swslot) {
uvm_swap_free(p->uanon->an_swslot, 1);
p->uanon->an_swslot = 0;
p->flags &= ~PG_CLEAN;
swap_shortage--;
}
if (p->pqflags & PQ_AOBJ) {
int slot = uao_set_swslot(p->uobject,
p->offset >> PAGE_SHIFT, 0);
if (slot) {
uvm_swap_free(slot, 1);
p->flags &= ~PG_CLEAN;
swap_shortage--;
}
}
}
/*
* deactivate this page if there's a shortage of
* inactive pages.
*/
if (inactive_shortage > 0) {
pmap_page_protect(p, VM_PROT_NONE);
/* no need to check wire_count as pg is "active" */
uvm_pagedeactivate(p);
uvmexp.pddeact++;
inactive_shortage--;
}
if (p->pqflags & PQ_ANON)
simple_unlock(&p->uanon->an_lock);
else
simple_unlock(&p->uobject->vmobjlock);
}
}
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