/* $NetBSD: uvm_pdaemon.c,v 1.64 2005/05/11 13:02:26 yamt 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. */ /* * uvm_pdaemon.c: the page daemon */ #include __KERNEL_RCSID(0, "$NetBSD: uvm_pdaemon.c,v 1.64 2005/05/11 13:02:26 yamt Exp $"); #include "opt_uvmhist.h" #include #include #include #include #include #include #include #include /* * UVMPD_NUMDIRTYREACTS is how many dirty pages the pagedaemon 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 */ void uvmpd_scan(void); void uvmpd_scan_inactive(struct pglist *); void uvmpd_tune(void); /* * XXX hack to avoid hangs when large processes fork. */ int uvm_extrapages; /* * 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 && uvmexp.paging == 0) { /* * 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 */ void uvmpd_tune(void) { 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.freetarg += uvm_extrapages; uvm_extrapages = 0; /* 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 bufcnt, npages = 0; int extrapages = 0; UVMHIST_FUNC("uvm_pageout"); UVMHIST_CALLED(pdhist); UVMHIST_LOG(pdhist,"", 0, 0, 0, 0); /* * ensure correct priority and set paging parameters... */ uvm.pagedaemon_proc = curproc; uvm_lock_pageq(); npages = uvmexp.npages; uvmpd_tune(); uvm_unlock_pageq(); /* * main loop */ for (;;) { simple_lock(&uvm.pagedaemon_lock); UVMHIST_LOG(pdhist," <>",0,0,0,0); UVM_UNLOCK_AND_WAIT(&uvm.pagedaemon, &uvm.pagedaemon_lock, FALSE, "pgdaemon", 0); uvmexp.pdwoke++; UVMHIST_LOG(pdhist," <>",0,0,0,0); /* * now lock page queues and recompute inactive count */ uvm_lock_pageq(); if (npages != uvmexp.npages || extrapages != uvm_extrapages) { npages = uvmexp.npages; extrapages = uvm_extrapages; uvmpd_tune(); } uvmexp.inactarg = (uvmexp.active + uvmexp.inactive) / 3; if (uvmexp.inactarg <= uvmexp.freetarg) { uvmexp.inactarg = uvmexp.freetarg + 1; } /* * Estimate a hint. Note that bufmem are returned to * system only when entire pool page is empty. */ bufcnt = uvmexp.freetarg - uvmexp.free; if (bufcnt < 0) bufcnt = 0; 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) { 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(); buf_drain(bufcnt << PAGE_SHIFT); /* * drain pool resources now that we're not holding any locks */ pool_drain(0); /* * free any cached u-areas we don't need */ uvm_uarea_drain(TRUE); } /*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," <>",0,0,0,0); UVM_UNLOCK_AND_WAIT(&uvm.aiodoned, &uvm.aiodoned_lock, FALSE, "aiodoned", 0); UVMHIST_LOG(pdhist," <>",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) { 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 */ void uvmpd_scan_inactive(pglst) struct pglist *pglst; { int error; struct vm_page *p, *nextpg = NULL; /* Quell compiler warning */ struct uvm_object *uobj; struct vm_anon *anon; struct vm_page *swpps[round_page(MAXPHYS) >> PAGE_SHIFT]; struct simplelock *slock; int swnpages, swcpages; int swslot; int dirtyreacts, t, result; boolean_t anonunder, fileunder, execunder; boolean_t anonover, fileover, execover; boolean_t anonreact, filereact, execreact; UVMHIST_FUNC("uvmpd_scan_inactive"); UVMHIST_CALLED(pdhist); /* * 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; dirtyreacts = 0; /* * decide which types of pages we want to reactivate instead of freeing * to keep usage within the minimum and maximum usage limits. */ t = uvmexp.active + uvmexp.inactive + uvmexp.free; anonunder = (uvmexp.anonpages <= (t * uvmexp.anonmin) >> 8); fileunder = (uvmexp.filepages <= (t * uvmexp.filemin) >> 8); execunder = (uvmexp.execpages <= (t * uvmexp.execmin) >> 8); anonover = uvmexp.anonpages > ((t * uvmexp.anonmax) >> 8); fileover = uvmexp.filepages > ((t * uvmexp.filemax) >> 8); execover = uvmexp.execpages > ((t * uvmexp.execmax) >> 8); anonreact = anonunder || (!anonover && (fileover || execover)); filereact = fileunder || (!fileover && (anonover || execover)); execreact = execunder || (!execover && (anonover || fileover)); if (filereact && execreact && (anonreact || uvm_swapisfull())) { anonreact = filereact = execreact = FALSE; } for (p = TAILQ_FIRST(pglst); p != NULL || swslot != 0; p = nextpg) { uobj = NULL; anon = NULL; if (p) { /* * see if we've met the free target. */ if (uvmexp.free + uvmexp.paging >= uvmexp.freetarg << 2 || dirtyreacts == UVMPD_NUMDIRTYREACTS) { UVMHIST_LOG(pdhist," met free target: " "exit loop", 0, 0, 0, 0); if (swslot == 0) { /* exit now if no swap-i/o pending */ break; } /* set p to null to signal final swap i/o */ p = NULL; nextpg = NULL; } } 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); /* * move referenced pages back to active queue and * skip to next page. */ if (pmap_clear_reference(p)) { uvm_pageactivate(p); uvmexp.pdreact++; continue; } anon = p->uanon; uobj = p->uobject; /* * enforce the minimum thresholds on different * types of memory usage. if reusing the current * page would reduce that type of usage below its * minimum, reactivate the page instead and move * on to the next page. */ if (uobj && UVM_OBJ_IS_VTEXT(uobj) && execreact) { uvm_pageactivate(p); uvmexp.pdreexec++; continue; } if (uobj && UVM_OBJ_IS_VNODE(uobj) && !UVM_OBJ_IS_VTEXT(uobj) && filereact) { uvm_pageactivate(p); uvmexp.pdrefile++; continue; } if ((anon || UVM_OBJ_IS_AOBJ(uobj)) && anonreact) { uvm_pageactivate(p); uvmexp.pdreanon++; continue; } /* * 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. */ /* does the page belong to an object? */ if (uobj != NULL) { slock = &uobj->vmobjlock; if (!simple_lock_try(slock)) { continue; } if (p->flags & PG_BUSY) { simple_unlock(slock); uvmexp.pdbusy++; continue; } uvmexp.pdobscan++; } else { KASSERT(anon != NULL); slock = &anon->an_lock; if (!simple_lock_try(slock)) { continue; } /* * set PQ_ANON if it isn't set already. */ 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(slock); uvmexp.pdbusy++; continue; } uvmexp.pdanscan++; } /* * we now have the object and the page queues locked. * if the page is not swap-backed, call the object's * pager to flush and free the page. */ if ((p->pqflags & PQ_SWAPBACKED) == 0) { uvm_unlock_pageq(); (void) (uobj->pgops->pgo_put)(uobj, p->offset, p->offset + PAGE_SIZE, PGO_CLEANIT|PGO_FREE); uvm_lock_pageq(); if (nextpg && (nextpg->pqflags & PQ_INACTIVE) == 0) { nextpg = TAILQ_FIRST(pglst); } continue; } /* * the page is swap-backed. remove all the permissions * from the page so we can sync the modified info * without any race conditions. if the page is clean * we can free it now and continue. */ pmap_page_protect(p, VM_PROT_NONE); if ((p->flags & PG_CLEAN) && pmap_clear_modify(p)) { p->flags &= ~(PG_CLEAN); } if (p->flags & PG_CLEAN) { int slot; int pageidx; pageidx = p->offset >> PAGE_SHIFT; uvm_pagefree(p); uvmexp.pdfreed++; /* * for anons, we need to remove the page * from the anon ourselves. for aobjs, * pagefree did that for us. */ if (anon) { KASSERT(anon->an_swslot != 0); anon->an_page = NULL; slot = anon->an_swslot; } else { slot = uao_find_swslot(uobj, pageidx); } simple_unlock(slock); if (slot > 0) { /* this page is now only in swap. */ simple_lock(&uvm.swap_data_lock); KASSERT(uvmexp.swpgonly < uvmexp.swpginuse); uvmexp.swpgonly++; simple_unlock(&uvm.swap_data_lock); } continue; } /* * this page is dirty, skip it if we'll have met our * free target when all the current pageouts complete. */ if (uvmexp.free + uvmexp.paging > uvmexp.freetarg << 2) { simple_unlock(slock); continue; } /* * free any swap space allocated to the page since * we'll have to write it again with its new data. */ if ((p->pqflags & PQ_ANON) && anon->an_swslot) { uvm_swap_free(anon->an_swslot, 1); anon->an_swslot = 0; } else if (p->pqflags & PQ_AOBJ) { uao_dropswap(uobj, p->offset >> PAGE_SHIFT); } /* * if all pages in swap are only in swap, * the swap space is full and we can't page out * any more swap-backed pages. reactivate this page * so that we eventually cycle all pages through * the inactive queue. */ if (uvm_swapisfull()) { dirtyreacts++; uvm_pageactivate(p); simple_unlock(slock); continue; } /* * start new swap pageout cluster (if necessary). */ if (swslot == 0) { /* Even with strange MAXPHYS, the shift implicitly rounds down to a page. */ swnpages = MAXPHYS >> PAGE_SHIFT; swslot = uvm_swap_alloc(&swnpages, TRUE); if (swslot == 0) { simple_unlock(slock); continue; } swcpages = 0; } /* * at this point, we're definitely going reuse this * page. mark the page busy and delayed-free. * we should remove the page from the page queues * so we don't ever look at it again. * adjust counters and such. */ p->flags |= PG_BUSY; UVM_PAGE_OWN(p, "scan_inactive"); p->flags |= PG_PAGEOUT; uvmexp.paging++; uvm_pagedequeue(p); uvmexp.pgswapout++; /* * add the new page to the cluster. */ if (anon) { anon->an_swslot = swslot + swcpages; simple_unlock(slock); } else { result = uao_set_swslot(uobj, p->offset >> PAGE_SHIFT, swslot + swcpages); if (result == -1) { p->flags &= ~(PG_BUSY|PG_PAGEOUT); UVM_PAGE_OWN(p, NULL); uvmexp.paging--; uvm_pageactivate(p); simple_unlock(slock); continue; } simple_unlock(slock); } swpps[swcpages] = p; swcpages++; /* * if the cluster isn't full, look for more pages * before starting the i/o. */ if (swcpages < swnpages) { continue; } } /* * if this is the final pageout we could have a few * unused swap blocks. if so, free them now. */ if (swcpages < swnpages) { uvm_swap_free(swslot + swcpages, (swnpages - swcpages)); } /* * now start the pageout. */ uvm_unlock_pageq(); uvmexp.pdpageouts++; error = uvm_swap_put(swslot, swpps, swcpages, 0); KASSERT(error == 0); uvm_lock_pageq(); /* * zero swslot to indicate that we are * no longer building a swap-backed cluster. */ swslot = 0; /* * the pageout is in progress. bump counters and set up * for the next loop. */ uvmexp.pdpending++; if (nextpg && (nextpg->pqflags & PQ_INACTIVE) == 0) { nextpg = TAILQ_FIRST(pglst); } } } /* * uvmpd_scan: scan the page queues and attempt to meet our targets. * * => called with pageq's locked */ void uvmpd_scan(void) { int inactive_shortage, swap_shortage, pages_freed; struct vm_page *p, *nextpg; struct uvm_object *uobj; struct vm_anon *anon; struct simplelock *slock; UVMHIST_FUNC("uvmpd_scan"); UVMHIST_CALLED(pdhist); uvmexp.pdrevs++; uobj = NULL; anon = NULL; #ifndef __SWAP_BROKEN /* * swap out some processes if we are below our free target. * we need to unlock the page queues for this. */ if (uvmexp.free < uvmexp.freetarg && uvmexp.nswapdev != 0) { uvmexp.pdswout++; UVMHIST_LOG(pdhist," free %d < target %d: swapout", uvmexp.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); pages_freed = uvmexp.pdfreed; uvmpd_scan_inactive(&uvm.page_inactive); 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.swpgavail && !uvm_swapisfull() && 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; } /* * lock the page's owner. */ if (p->uobject != NULL) { uobj = p->uobject; slock = &uobj->vmobjlock; if (!simple_lock_try(slock)) { continue; } } else { anon = p->uanon; KASSERT(anon != NULL); slock = &anon->an_lock; if (!simple_lock_try(slock)) { continue; } /* take over the page? */ if ((p->pqflags & PQ_ANON) == 0) { KASSERT(p->loan_count > 0); p->loan_count--; p->pqflags |= PQ_ANON; } } /* * skip this page if it's busy. */ if ((p->flags & PG_BUSY) != 0) { simple_unlock(slock); 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) && anon->an_swslot) { uvm_swap_free(anon->an_swslot, 1); anon->an_swslot = 0; p->flags &= ~PG_CLEAN; swap_shortage--; } else if (p->pqflags & PQ_AOBJ) { int slot = uao_set_swslot(uobj, p->offset >> PAGE_SHIFT, 0); if (slot) { uvm_swap_free(slot, 1); p->flags &= ~PG_CLEAN; swap_shortage--; } } } /* * if there's a shortage of inactive pages, deactivate. */ if (inactive_shortage > 0) { /* no need to check wire_count as pg is "active" */ uvm_pagedeactivate(p); uvmexp.pddeact++; inactive_shortage--; } /* * we're done with this page. */ simple_unlock(slock); } } /* * uvm_reclaimable: decide whether to wait for pagedaemon. * * => return TRUE if it seems to be worth to do uvm_wait. * * XXX should be tunable. * XXX should consider pools, etc? */ boolean_t uvm_reclaimable(void) { int filepages; /* * if swap is not full, no problem. */ if (!uvm_swapisfull()) { return TRUE; } /* * file-backed pages can be reclaimed even when swap is full. * if we have more than 1/16 of pageable memory or 5MB, try to reclaim. * * XXX assume the worst case, ie. all wired pages are file-backed. * * XXX should consider about other reclaimable memory. * XXX ie. pools, traditional buffer cache. */ filepages = uvmexp.filepages + uvmexp.execpages - uvmexp.wired; if (filepages >= MIN((uvmexp.active + uvmexp.inactive) >> 4, 5 * 1024 * 1024 >> PAGE_SHIFT)) { return TRUE; } /* * kill the process, fail allocation, etc.. */ return FALSE; }