/*- * Copyright (c) 1991 Regents of the University of California. * All rights reserved. * Copyright (c) 1994 John S. Dyson * All rights reserved. * Copyright (c) 1994 David Greenman * 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 * 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. * * from: @(#)vm_pageout.c 7.4 (Berkeley) 5/7/91 * * * Copyright (c) 1987, 1990 Carnegie-Mellon University. * 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 * * 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. */ /* * The proverbial page-out daemon. */ #include __FBSDID("$FreeBSD$"); #include "opt_vm.h" #include "opt_kdtrace.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* * System initialization */ /* the kernel process "vm_pageout"*/ static void vm_pageout(void); static void vm_pageout_init(void); static int vm_pageout_clean(vm_page_t); static void vm_pageout_scan(struct vm_domain *vmd, int pass); static void vm_pageout_mightbe_oom(struct vm_domain *vmd, int pass); SYSINIT(pagedaemon_init, SI_SUB_KTHREAD_PAGE, SI_ORDER_FIRST, vm_pageout_init, NULL); struct proc *pageproc; static struct kproc_desc page_kp = { "pagedaemon", vm_pageout, &pageproc }; SYSINIT(pagedaemon, SI_SUB_KTHREAD_PAGE, SI_ORDER_SECOND, kproc_start, &page_kp); SDT_PROVIDER_DEFINE(vm); SDT_PROBE_DEFINE(vm, , , vm__lowmem_cache); SDT_PROBE_DEFINE(vm, , , vm__lowmem_scan); #if !defined(NO_SWAPPING) /* the kernel process "vm_daemon"*/ static void vm_daemon(void); static struct proc *vmproc; static struct kproc_desc vm_kp = { "vmdaemon", vm_daemon, &vmproc }; SYSINIT(vmdaemon, SI_SUB_KTHREAD_VM, SI_ORDER_FIRST, kproc_start, &vm_kp); #endif int vm_pages_needed; /* Event on which pageout daemon sleeps */ int vm_pageout_deficit; /* Estimated number of pages deficit */ int vm_pageout_pages_needed; /* flag saying that the pageout daemon needs pages */ int vm_pageout_wakeup_thresh; #if !defined(NO_SWAPPING) static int vm_pageout_req_swapout; /* XXX */ static int vm_daemon_needed; static struct mtx vm_daemon_mtx; /* Allow for use by vm_pageout before vm_daemon is initialized. */ MTX_SYSINIT(vm_daemon, &vm_daemon_mtx, "vm daemon", MTX_DEF); #endif static int vm_max_launder = 32; static int vm_pageout_update_period; static int defer_swap_pageouts; static int disable_swap_pageouts; static int lowmem_period = 10; static int lowmem_ticks; #if defined(NO_SWAPPING) static int vm_swap_enabled = 0; static int vm_swap_idle_enabled = 0; #else static int vm_swap_enabled = 1; static int vm_swap_idle_enabled = 0; #endif SYSCTL_INT(_vm, OID_AUTO, pageout_wakeup_thresh, CTLFLAG_RW, &vm_pageout_wakeup_thresh, 0, "free page threshold for waking up the pageout daemon"); SYSCTL_INT(_vm, OID_AUTO, max_launder, CTLFLAG_RW, &vm_max_launder, 0, "Limit dirty flushes in pageout"); SYSCTL_INT(_vm, OID_AUTO, pageout_update_period, CTLFLAG_RW, &vm_pageout_update_period, 0, "Maximum active LRU update period"); SYSCTL_INT(_vm, OID_AUTO, lowmem_period, CTLFLAG_RW, &lowmem_period, 0, "Low memory callback period"); #if defined(NO_SWAPPING) SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled, CTLFLAG_RD, &vm_swap_enabled, 0, "Enable entire process swapout"); SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled, CTLFLAG_RD, &vm_swap_idle_enabled, 0, "Allow swapout on idle criteria"); #else SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled, CTLFLAG_RW, &vm_swap_enabled, 0, "Enable entire process swapout"); SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled, CTLFLAG_RW, &vm_swap_idle_enabled, 0, "Allow swapout on idle criteria"); #endif SYSCTL_INT(_vm, OID_AUTO, defer_swapspace_pageouts, CTLFLAG_RW, &defer_swap_pageouts, 0, "Give preference to dirty pages in mem"); SYSCTL_INT(_vm, OID_AUTO, disable_swapspace_pageouts, CTLFLAG_RW, &disable_swap_pageouts, 0, "Disallow swapout of dirty pages"); static int pageout_lock_miss; SYSCTL_INT(_vm, OID_AUTO, pageout_lock_miss, CTLFLAG_RD, &pageout_lock_miss, 0, "vget() lock misses during pageout"); #define VM_PAGEOUT_PAGE_COUNT 16 int vm_pageout_page_count = VM_PAGEOUT_PAGE_COUNT; int vm_page_max_wired; /* XXX max # of wired pages system-wide */ SYSCTL_INT(_vm, OID_AUTO, max_wired, CTLFLAG_RW, &vm_page_max_wired, 0, "System-wide limit to wired page count"); static boolean_t vm_pageout_fallback_object_lock(vm_page_t, vm_page_t *); static boolean_t vm_pageout_launder(struct vm_pagequeue *pq, int, vm_paddr_t, vm_paddr_t); #if !defined(NO_SWAPPING) static void vm_pageout_map_deactivate_pages(vm_map_t, long); static void vm_pageout_object_deactivate_pages(pmap_t, vm_object_t, long); static void vm_req_vmdaemon(int req); #endif static boolean_t vm_pageout_page_lock(vm_page_t, vm_page_t *); /* * Initialize a dummy page for marking the caller's place in the specified * paging queue. In principle, this function only needs to set the flag * PG_MARKER. Nonetheless, it wirte busies and initializes the hold count * to one as safety precautions. */ static void vm_pageout_init_marker(vm_page_t marker, u_short queue) { bzero(marker, sizeof(*marker)); marker->flags = PG_MARKER; marker->busy_lock = VPB_SINGLE_EXCLUSIVER; marker->queue = queue; marker->hold_count = 1; } /* * vm_pageout_fallback_object_lock: * * Lock vm object currently associated with `m'. VM_OBJECT_TRYWLOCK is * known to have failed and page queue must be either PQ_ACTIVE or * PQ_INACTIVE. To avoid lock order violation, unlock the page queues * while locking the vm object. 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. vm object is * locked on return. * * This function depends on both the lock portion of struct vm_object * and normal struct vm_page being type stable. */ static boolean_t vm_pageout_fallback_object_lock(vm_page_t m, vm_page_t *next) { struct vm_page marker; struct vm_pagequeue *pq; boolean_t unchanged; u_short queue; vm_object_t object; queue = m->queue; vm_pageout_init_marker(&marker, queue); pq = vm_page_pagequeue(m); object = m->object; TAILQ_INSERT_AFTER(&pq->pq_pl, m, &marker, plinks.q); vm_pagequeue_unlock(pq); vm_page_unlock(m); VM_OBJECT_WLOCK(object); vm_page_lock(m); vm_pagequeue_lock(pq); /* Page queue might have changed. */ *next = TAILQ_NEXT(&marker, plinks.q); unchanged = (m->queue == queue && m->object == object && &marker == TAILQ_NEXT(m, plinks.q)); 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->queue == queue && &marker == TAILQ_NEXT(m, plinks.q)); TAILQ_REMOVE(&pq->pq_pl, &marker, plinks.q); return (unchanged); } /* * vm_pageout_clean: * * Clean the page and remove it from the laundry. * * We set the busy bit to cause potential page faults on this page to * block. Note the careful timing, however, the busy bit isn't set till * late and we cannot do anything that will mess with the page. */ static int vm_pageout_clean(vm_page_t m) { vm_object_t object; vm_page_t mc[2*vm_pageout_page_count], pb, ps; int pageout_count; int ib, is, page_base; vm_pindex_t pindex = m->pindex; vm_page_lock_assert(m, MA_OWNED); object = m->object; VM_OBJECT_ASSERT_WLOCKED(object); /* * It doesn't cost us anything to pageout OBJT_DEFAULT or OBJT_SWAP * with the new swapper, but we could have serious problems paging * out other object types if there is insufficient memory. * * Unfortunately, checking free memory here is far too late, so the * check has been moved up a procedural level. */ /* * Can't clean the page if it's busy or held. */ vm_page_assert_unbusied(m); KASSERT(m->hold_count == 0, ("vm_pageout_clean: page %p is held", m)); vm_page_unlock(m); mc[vm_pageout_page_count] = pb = ps = m; pageout_count = 1; page_base = vm_pageout_page_count; ib = 1; is = 1; /* * Scan object for clusterable pages. * * We can cluster ONLY if: ->> the page is NOT * clean, wired, busy, held, or mapped into a * buffer, and one of the following: * 1) The page is inactive, or a seldom used * active page. * -or- * 2) we force the issue. * * During heavy mmap/modification loads the pageout * daemon can really fragment the underlying file * due to flushing pages out of order and not trying * align the clusters (which leave sporatic out-of-order * holes). To solve this problem we do the reverse scan * first and attempt to align our cluster, then do a * forward scan if room remains. */ more: while (ib && pageout_count < vm_pageout_page_count) { vm_page_t p; if (ib > pindex) { ib = 0; break; } if ((p = vm_page_prev(pb)) == NULL || vm_page_busied(p)) { ib = 0; break; } vm_page_lock(p); vm_page_test_dirty(p); if (p->dirty == 0 || p->queue != PQ_INACTIVE || p->hold_count != 0) { /* may be undergoing I/O */ vm_page_unlock(p); ib = 0; break; } vm_page_unlock(p); mc[--page_base] = pb = p; ++pageout_count; ++ib; /* * alignment boundry, stop here and switch directions. Do * not clear ib. */ if ((pindex - (ib - 1)) % vm_pageout_page_count == 0) break; } while (pageout_count < vm_pageout_page_count && pindex + is < object->size) { vm_page_t p; if ((p = vm_page_next(ps)) == NULL || vm_page_busied(p)) break; vm_page_lock(p); vm_page_test_dirty(p); if (p->dirty == 0 || p->queue != PQ_INACTIVE || p->hold_count != 0) { /* may be undergoing I/O */ vm_page_unlock(p); break; } vm_page_unlock(p); mc[page_base + pageout_count] = ps = p; ++pageout_count; ++is; } /* * If we exhausted our forward scan, continue with the reverse scan * when possible, even past a page boundry. This catches boundry * conditions. */ if (ib && pageout_count < vm_pageout_page_count) goto more; /* * we allow reads during pageouts... */ return (vm_pageout_flush(&mc[page_base], pageout_count, 0, 0, NULL, NULL)); } /* * vm_pageout_flush() - launder the given pages * * The given pages are laundered. Note that we setup for the start of * I/O ( i.e. busy the page ), mark it read-only, and bump the object * reference count all in here rather then in the parent. If we want * the parent to do more sophisticated things we may have to change * the ordering. * * Returned runlen is the count of pages between mreq and first * page after mreq with status VM_PAGER_AGAIN. * *eio is set to TRUE if pager returned VM_PAGER_ERROR or VM_PAGER_FAIL * for any page in runlen set. */ int vm_pageout_flush(vm_page_t *mc, int count, int flags, int mreq, int *prunlen, boolean_t *eio) { vm_object_t object = mc[0]->object; int pageout_status[count]; int numpagedout = 0; int i, runlen; VM_OBJECT_ASSERT_WLOCKED(object); /* * Initiate I/O. Bump the vm_page_t->busy counter and * mark the pages read-only. * * We do not have to fixup the clean/dirty bits here... we can * allow the pager to do it after the I/O completes. * * NOTE! mc[i]->dirty may be partial or fragmented due to an * edge case with file fragments. */ for (i = 0; i < count; i++) { KASSERT(mc[i]->valid == VM_PAGE_BITS_ALL, ("vm_pageout_flush: partially invalid page %p index %d/%d", mc[i], i, count)); vm_page_sbusy(mc[i]); pmap_remove_write(mc[i]); } vm_object_pip_add(object, count); vm_pager_put_pages(object, mc, count, flags, pageout_status); runlen = count - mreq; if (eio != NULL) *eio = FALSE; for (i = 0; i < count; i++) { vm_page_t mt = mc[i]; KASSERT(pageout_status[i] == VM_PAGER_PEND || !pmap_page_is_write_mapped(mt), ("vm_pageout_flush: page %p is not write protected", mt)); switch (pageout_status[i]) { case VM_PAGER_OK: case VM_PAGER_PEND: numpagedout++; break; case VM_PAGER_BAD: /* * Page outside of range of object. Right now we * essentially lose the changes by pretending it * worked. */ vm_page_undirty(mt); break; case VM_PAGER_ERROR: case VM_PAGER_FAIL: /* * If page couldn't be paged out, then reactivate the * page so it doesn't clog the inactive list. (We * will try paging out it again later). */ vm_page_lock(mt); vm_page_activate(mt); vm_page_unlock(mt); if (eio != NULL && i >= mreq && i - mreq < runlen) *eio = TRUE; break; case VM_PAGER_AGAIN: if (i >= mreq && i - mreq < runlen) runlen = i - mreq; break; } /* * If the operation is still going, leave the page busy to * block all other accesses. Also, leave the paging in * progress indicator set so that we don't attempt an object * collapse. */ if (pageout_status[i] != VM_PAGER_PEND) { vm_object_pip_wakeup(object); vm_page_sunbusy(mt); if (vm_page_count_severe()) { vm_page_lock(mt); vm_page_try_to_cache(mt); vm_page_unlock(mt); } } } if (prunlen != NULL) *prunlen = runlen; return (numpagedout); } static boolean_t vm_pageout_launder(struct vm_pagequeue *pq, int tries, vm_paddr_t low, vm_paddr_t high) { struct mount *mp; struct vnode *vp; vm_object_t object; vm_paddr_t pa; vm_page_t m, m_tmp, next; int lockmode; vm_pagequeue_lock(pq); TAILQ_FOREACH_SAFE(m, &pq->pq_pl, plinks.q, next) { if ((m->flags & PG_MARKER) != 0) continue; pa = VM_PAGE_TO_PHYS(m); if (pa < low || pa + PAGE_SIZE > high) continue; if (!vm_pageout_page_lock(m, &next) || m->hold_count != 0) { vm_page_unlock(m); continue; } object = m->object; if ((!VM_OBJECT_TRYWLOCK(object) && (!vm_pageout_fallback_object_lock(m, &next) || m->hold_count != 0)) || vm_page_busied(m)) { vm_page_unlock(m); VM_OBJECT_WUNLOCK(object); continue; } vm_page_test_dirty(m); if (m->dirty == 0 && object->ref_count != 0) pmap_remove_all(m); if (m->dirty != 0) { vm_page_unlock(m); if (tries == 0 || (object->flags & OBJ_DEAD) != 0) { VM_OBJECT_WUNLOCK(object); continue; } if (object->type == OBJT_VNODE) { vm_pagequeue_unlock(pq); vp = object->handle; vm_object_reference_locked(object); VM_OBJECT_WUNLOCK(object); (void)vn_start_write(vp, &mp, V_WAIT); lockmode = MNT_SHARED_WRITES(vp->v_mount) ? LK_SHARED : LK_EXCLUSIVE; vn_lock(vp, lockmode | LK_RETRY); VM_OBJECT_WLOCK(object); vm_object_page_clean(object, 0, 0, OBJPC_SYNC); VM_OBJECT_WUNLOCK(object); VOP_UNLOCK(vp, 0); vm_object_deallocate(object); vn_finished_write(mp); return (TRUE); } else if (object->type == OBJT_SWAP || object->type == OBJT_DEFAULT) { vm_pagequeue_unlock(pq); m_tmp = m; vm_pageout_flush(&m_tmp, 1, VM_PAGER_PUT_SYNC, 0, NULL, NULL); VM_OBJECT_WUNLOCK(object); return (TRUE); } } else { /* * Dequeue here to prevent lock recursion in * vm_page_cache(). */ vm_page_dequeue_locked(m); vm_page_cache(m); vm_page_unlock(m); } VM_OBJECT_WUNLOCK(object); } vm_pagequeue_unlock(pq); return (FALSE); } /* * Increase the number of cached pages. The specified value, "tries", * determines which categories of pages are cached: * * 0: All clean, inactive pages within the specified physical address range * are cached. Will not sleep. * 1: The vm_lowmem handlers are called. All inactive pages within * the specified physical address range are cached. May sleep. * 2: The vm_lowmem handlers are called. All inactive and active pages * within the specified physical address range are cached. May sleep. */ void vm_pageout_grow_cache(int tries, vm_paddr_t low, vm_paddr_t high) { int actl, actmax, inactl, inactmax, dom, initial_dom; static int start_dom = 0; if (tries > 0) { /* * Decrease registered cache sizes. The vm_lowmem handlers * may acquire locks and/or sleep, so they can only be invoked * when "tries" is greater than zero. */ SDT_PROBE0(vm, , , vm__lowmem_cache); EVENTHANDLER_INVOKE(vm_lowmem, 0); /* * We do this explicitly after the caches have been drained * above. */ uma_reclaim(); } /* * Make the next scan start on the next domain. */ initial_dom = atomic_fetchadd_int(&start_dom, 1) % vm_ndomains; inactl = 0; inactmax = cnt.v_inactive_count; actl = 0; actmax = tries < 2 ? 0 : cnt.v_active_count; dom = initial_dom; /* * Scan domains in round-robin order, first inactive queues, * then active. Since domain usually owns large physically * contiguous chunk of memory, it makes sense to completely * exhaust one domain before switching to next, while growing * the pool of contiguous physical pages. * * Do not even start launder a domain which cannot contain * the specified address range, as indicated by segments * constituting the domain. */ again: if (inactl < inactmax) { if (vm_phys_domain_intersects(vm_dom[dom].vmd_segs, low, high) && vm_pageout_launder(&vm_dom[dom].vmd_pagequeues[PQ_INACTIVE], tries, low, high)) { inactl++; goto again; } if (++dom == vm_ndomains) dom = 0; if (dom != initial_dom) goto again; } if (actl < actmax) { if (vm_phys_domain_intersects(vm_dom[dom].vmd_segs, low, high) && vm_pageout_launder(&vm_dom[dom].vmd_pagequeues[PQ_ACTIVE], tries, low, high)) { actl++; goto again; } if (++dom == vm_ndomains) dom = 0; if (dom != initial_dom) goto again; } } #if !defined(NO_SWAPPING) /* * vm_pageout_object_deactivate_pages * * Deactivate enough pages to satisfy the inactive target * requirements. * * The object and map must be locked. */ static void vm_pageout_object_deactivate_pages(pmap_t pmap, vm_object_t first_object, long desired) { vm_object_t backing_object, object; vm_page_t p; int act_delta, remove_mode; VM_OBJECT_ASSERT_LOCKED(first_object); if ((first_object->flags & OBJ_FICTITIOUS) != 0) return; for (object = first_object;; object = backing_object) { if (pmap_resident_count(pmap) <= desired) goto unlock_return; VM_OBJECT_ASSERT_LOCKED(object); if ((object->flags & OBJ_UNMANAGED) != 0 || object->paging_in_progress != 0) goto unlock_return; remove_mode = 0; if (object->shadow_count > 1) remove_mode = 1; /* * Scan the object's entire memory queue. */ TAILQ_FOREACH(p, &object->memq, listq) { if (pmap_resident_count(pmap) <= desired) goto unlock_return; if (vm_page_busied(p)) continue; PCPU_INC(cnt.v_pdpages); vm_page_lock(p); if (p->wire_count != 0 || p->hold_count != 0 || !pmap_page_exists_quick(pmap, p)) { vm_page_unlock(p); continue; } act_delta = pmap_ts_referenced(p); if ((p->aflags & PGA_REFERENCED) != 0) { if (act_delta == 0) act_delta = 1; vm_page_aflag_clear(p, PGA_REFERENCED); } if (p->queue != PQ_ACTIVE && act_delta != 0) { vm_page_activate(p); p->act_count += act_delta; } else if (p->queue == PQ_ACTIVE) { if (act_delta == 0) { p->act_count -= min(p->act_count, ACT_DECLINE); if (!remove_mode && p->act_count == 0) { pmap_remove_all(p); vm_page_deactivate(p); } else vm_page_requeue(p); } else { vm_page_activate(p); if (p->act_count < ACT_MAX - ACT_ADVANCE) p->act_count += ACT_ADVANCE; vm_page_requeue(p); } } else if (p->queue == PQ_INACTIVE) pmap_remove_all(p); vm_page_unlock(p); } if ((backing_object = object->backing_object) == NULL) goto unlock_return; VM_OBJECT_RLOCK(backing_object); if (object != first_object) VM_OBJECT_RUNLOCK(object); } unlock_return: if (object != first_object) VM_OBJECT_RUNLOCK(object); } /* * deactivate some number of pages in a map, try to do it fairly, but * that is really hard to do. */ static void vm_pageout_map_deactivate_pages(map, desired) vm_map_t map; long desired; { vm_map_entry_t tmpe; vm_object_t obj, bigobj; int nothingwired; if (!vm_map_trylock(map)) return; bigobj = NULL; nothingwired = TRUE; /* * first, search out the biggest object, and try to free pages from * that. */ tmpe = map->header.next; while (tmpe != &map->header) { if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) { obj = tmpe->object.vm_object; if (obj != NULL && VM_OBJECT_TRYRLOCK(obj)) { if (obj->shadow_count <= 1 && (bigobj == NULL || bigobj->resident_page_count < obj->resident_page_count)) { if (bigobj != NULL) VM_OBJECT_RUNLOCK(bigobj); bigobj = obj; } else VM_OBJECT_RUNLOCK(obj); } } if (tmpe->wired_count > 0) nothingwired = FALSE; tmpe = tmpe->next; } if (bigobj != NULL) { vm_pageout_object_deactivate_pages(map->pmap, bigobj, desired); VM_OBJECT_RUNLOCK(bigobj); } /* * Next, hunt around for other pages to deactivate. We actually * do this search sort of wrong -- .text first is not the best idea. */ tmpe = map->header.next; while (tmpe != &map->header) { if (pmap_resident_count(vm_map_pmap(map)) <= desired) break; if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) { obj = tmpe->object.vm_object; if (obj != NULL) { VM_OBJECT_RLOCK(obj); vm_pageout_object_deactivate_pages(map->pmap, obj, desired); VM_OBJECT_RUNLOCK(obj); } } tmpe = tmpe->next; } #ifdef __ia64__ /* * Remove all non-wired, managed mappings if a process is swapped out. * This will free page table pages. */ if (desired == 0) pmap_remove_pages(map->pmap); #else /* * Remove all mappings if a process is swapped out, this will free page * table pages. */ if (desired == 0 && nothingwired) { pmap_remove(vm_map_pmap(map), vm_map_min(map), vm_map_max(map)); } #endif vm_map_unlock(map); } #endif /* !defined(NO_SWAPPING) */ /* * vm_pageout_scan does the dirty work for the pageout daemon. * * pass 0 - Update active LRU/deactivate pages * pass 1 - Move inactive to cache or free * pass 2 - Launder dirty pages */ static void vm_pageout_scan(struct vm_domain *vmd, int pass) { vm_page_t m, next; struct vm_pagequeue *pq; vm_object_t object; int act_delta, addl_page_shortage, deficit, maxscan, page_shortage; int vnodes_skipped = 0; int maxlaunder; int lockmode; boolean_t queues_locked; /* * If we need to reclaim memory ask kernel caches to return * some. We rate limit to avoid thrashing. */ if (vmd == &vm_dom[0] && pass > 0 && (ticks - lowmem_ticks) / hz >= 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_ticks = ticks; } /* * The addl_page_shortage is the number of temporarily * stuck pages in the inactive queue. In other words, the * number of pages from the inactive count that should be * discounted in setting the target for the active queue scan. */ addl_page_shortage = 0; /* * Calculate the number of pages we want to either free or move * to the cache. */ if (pass > 0) { deficit = atomic_readandclear_int(&vm_pageout_deficit); page_shortage = vm_paging_target() + deficit; } else page_shortage = deficit = 0; /* * maxlaunder limits the number of dirty pages we flush per scan. * For most systems a smaller value (16 or 32) is more robust under * extreme memory and disk pressure because any unnecessary writes * to disk can result in extreme performance degredation. However, * systems with excessive dirty pages (especially when MAP_NOSYNC is * used) will die horribly with limited laundering. If the pageout * daemon cannot clean enough pages in the first pass, we let it go * all out in succeeding passes. */ if ((maxlaunder = vm_max_launder) <= 1) maxlaunder = 1; if (pass > 1) maxlaunder = 10000; /* * Start scanning the inactive queue for pages we can move to the * cache or free. The scan will stop when the target is reached or * we have scanned the entire inactive queue. Note that m->act_count * is not used to form decisions for the inactive queue, only for the * active queue. */ pq = &vmd->vmd_pagequeues[PQ_INACTIVE]; maxscan = pq->pq_cnt; vm_pagequeue_lock(pq); queues_locked = TRUE; for (m = TAILQ_FIRST(&pq->pq_pl); m != NULL && maxscan-- > 0 && page_shortage > 0; m = next) { vm_pagequeue_assert_locked(pq); KASSERT(queues_locked, ("unlocked queues")); KASSERT(m->queue == PQ_INACTIVE, ("Inactive queue %p", m)); PCPU_INC(cnt.v_pdpages); next = TAILQ_NEXT(m, plinks.q); /* * skip marker pages */ if (m->flags & PG_MARKER) continue; KASSERT((m->flags & PG_FICTITIOUS) == 0, ("Fictitious page %p cannot be in inactive queue", m)); KASSERT((m->oflags & VPO_UNMANAGED) == 0, ("Unmanaged page %p cannot be in inactive queue", m)); /* * The page or object lock acquisitions fail if the * page was removed from the queue or moved to a * different position within the queue. In either * case, addl_page_shortage should not be incremented. */ if (!vm_pageout_page_lock(m, &next)) { vm_page_unlock(m); continue; } object = m->object; if (!VM_OBJECT_TRYWLOCK(object) && !vm_pageout_fallback_object_lock(m, &next)) { vm_page_unlock(m); VM_OBJECT_WUNLOCK(object); continue; } /* * Don't mess with busy pages, keep them at at the * front of the queue, most likely they are being * paged out. Increment addl_page_shortage for busy * pages, because they may leave the inactive queue * shortly after page scan is finished. */ if (vm_page_busied(m)) { vm_page_unlock(m); VM_OBJECT_WUNLOCK(object); addl_page_shortage++; continue; } /* * We unlock the inactive page queue, invalidating the * 'next' pointer. Use our marker to remember our * place. */ TAILQ_INSERT_AFTER(&pq->pq_pl, m, &vmd->vmd_marker, plinks.q); vm_pagequeue_unlock(pq); queues_locked = FALSE; /* * We bump the activation count if the page has been * referenced while in the inactive queue. This makes * it less likely that the page will be added back to the * inactive queue prematurely again. Here we check the * page tables (or emulated bits, if any), given the upper * level VM system not knowing anything about existing * references. */ act_delta = 0; if ((m->aflags & PGA_REFERENCED) != 0) { vm_page_aflag_clear(m, PGA_REFERENCED); act_delta = 1; } if (object->ref_count != 0) { act_delta += pmap_ts_referenced(m); } else { KASSERT(!pmap_page_is_mapped(m), ("vm_pageout_scan: page %p is mapped", m)); } /* * If the upper level VM system knows about any page * references, we reactivate the page or requeue it. */ if (act_delta != 0) { if (object->ref_count) { vm_page_activate(m); m->act_count += act_delta + ACT_ADVANCE; } else { vm_pagequeue_lock(pq); queues_locked = TRUE; vm_page_requeue_locked(m); } VM_OBJECT_WUNLOCK(object); vm_page_unlock(m); goto relock_queues; } if (m->hold_count != 0) { vm_page_unlock(m); VM_OBJECT_WUNLOCK(object); /* * Held pages are essentially stuck in the * queue. So, they ought to be discounted * from the inactive count. See the * calculation of the page_shortage for the * loop over the active queue below. */ addl_page_shortage++; goto relock_queues; } /* * If the page appears to be clean at the machine-independent * layer, then remove all of its mappings from the pmap in * anticipation of placing it onto the cache queue. If, * however, any of the page's mappings allow write access, * then the page may still be modified until the last of those * mappings are removed. */ vm_page_test_dirty(m); if (m->dirty == 0 && object->ref_count != 0) pmap_remove_all(m); if (m->valid == 0) { /* * Invalid pages can be easily freed */ vm_page_free(m); PCPU_INC(cnt.v_dfree); --page_shortage; } else if (m->dirty == 0) { /* * Clean pages can be placed onto the cache queue. * This effectively frees them. */ vm_page_cache(m); --page_shortage; } else if ((m->flags & PG_WINATCFLS) == 0 && pass < 2) { /* * Dirty pages need to be paged out, but flushing * a page is extremely expensive verses freeing * a clean page. Rather then artificially limiting * the number of pages we can flush, we instead give * dirty pages extra priority on the inactive queue * by forcing them to be cycled through the queue * twice before being flushed, after which the * (now clean) page will cycle through once more * before being freed. This significantly extends * the thrash point for a heavily loaded machine. */ m->flags |= PG_WINATCFLS; vm_pagequeue_lock(pq); queues_locked = TRUE; vm_page_requeue_locked(m); } else if (maxlaunder > 0) { /* * We always want to try to flush some dirty pages if * we encounter them, to keep the system stable. * Normally this number is small, but under extreme * pressure where there are insufficient clean pages * on the inactive queue, we may have to go all out. */ int swap_pageouts_ok; struct vnode *vp = NULL; struct mount *mp = NULL; if ((object->type != OBJT_SWAP) && (object->type != OBJT_DEFAULT)) { swap_pageouts_ok = 1; } else { swap_pageouts_ok = !(defer_swap_pageouts || disable_swap_pageouts); swap_pageouts_ok |= (!disable_swap_pageouts && defer_swap_pageouts && vm_page_count_min()); } /* * We don't bother paging objects that are "dead". * Those objects are in a "rundown" state. */ if (!swap_pageouts_ok || (object->flags & OBJ_DEAD)) { vm_pagequeue_lock(pq); vm_page_unlock(m); VM_OBJECT_WUNLOCK(object); queues_locked = TRUE; vm_page_requeue_locked(m); goto relock_queues; } /* * The object is already known NOT to be dead. It * is possible for the vget() to block the whole * pageout daemon, but the new low-memory handling * code should prevent it. * * The previous code skipped locked vnodes and, worse, * reordered pages in the queue. This results in * completely non-deterministic operation and, on a * busy system, can lead to extremely non-optimal * pageouts. For example, it can cause clean pages * to be freed and dirty pages to be moved to the end * of the queue. Since dirty pages are also moved to * the end of the queue once-cleaned, this gives * way too large a weighting to defering the freeing * of dirty pages. * * We can't wait forever for the vnode lock, we might * deadlock due to a vn_read() getting stuck in * vm_wait while holding this vnode. We skip the * vnode if we can't get it in a reasonable amount * of time. */ if (object->type == OBJT_VNODE) { vm_page_unlock(m); vp = object->handle; if (vp->v_type == VREG && vn_start_write(vp, &mp, V_NOWAIT) != 0) { mp = NULL; ++pageout_lock_miss; if (object->flags & OBJ_MIGHTBEDIRTY) vnodes_skipped++; goto unlock_and_continue; } KASSERT(mp != NULL, ("vp %p with NULL v_mount", vp)); vm_object_reference_locked(object); VM_OBJECT_WUNLOCK(object); lockmode = MNT_SHARED_WRITES(vp->v_mount) ? LK_SHARED : LK_EXCLUSIVE; if (vget(vp, lockmode | LK_TIMELOCK, curthread)) { VM_OBJECT_WLOCK(object); ++pageout_lock_miss; if (object->flags & OBJ_MIGHTBEDIRTY) vnodes_skipped++; vp = NULL; goto unlock_and_continue; } VM_OBJECT_WLOCK(object); vm_page_lock(m); vm_pagequeue_lock(pq); queues_locked = TRUE; /* * The page might have been moved to another * queue during potential blocking in vget() * above. The page might have been freed and * reused for another vnode. */ if (m->queue != PQ_INACTIVE || m->object != object || TAILQ_NEXT(m, plinks.q) != &vmd->vmd_marker) { vm_page_unlock(m); if (object->flags & OBJ_MIGHTBEDIRTY) vnodes_skipped++; goto unlock_and_continue; } /* * The page may have been busied during the * blocking in vget(). We don't move the * page back onto the end of the queue so that * statistics are more correct if we don't. */ if (vm_page_busied(m)) { vm_page_unlock(m); addl_page_shortage++; goto unlock_and_continue; } /* * If the page has become held it might * be undergoing I/O, so skip it */ if (m->hold_count != 0) { vm_page_unlock(m); addl_page_shortage++; if (object->flags & OBJ_MIGHTBEDIRTY) vnodes_skipped++; goto unlock_and_continue; } vm_pagequeue_unlock(pq); queues_locked = FALSE; } /* * If a page is dirty, then it is either being washed * (but not yet cleaned) or it is still in the * laundry. If it is still in the laundry, then we * start the cleaning operation. * * decrement page_shortage on success to account for * the (future) cleaned page. Otherwise we could wind * up laundering or cleaning too many pages. */ if (vm_pageout_clean(m) != 0) { --page_shortage; --maxlaunder; } unlock_and_continue: vm_page_lock_assert(m, MA_NOTOWNED); VM_OBJECT_WUNLOCK(object); if (mp != NULL) { if (queues_locked) { vm_pagequeue_unlock(pq); queues_locked = FALSE; } if (vp != NULL) vput(vp); vm_object_deallocate(object); vn_finished_write(mp); } vm_page_lock_assert(m, MA_NOTOWNED); goto relock_queues; } vm_page_unlock(m); VM_OBJECT_WUNLOCK(object); relock_queues: if (!queues_locked) { vm_pagequeue_lock(pq); queues_locked = TRUE; } next = TAILQ_NEXT(&vmd->vmd_marker, plinks.q); TAILQ_REMOVE(&pq->pq_pl, &vmd->vmd_marker, plinks.q); } vm_pagequeue_unlock(pq); #if !defined(NO_SWAPPING) /* * Wakeup the swapout daemon if we didn't cache or free the targeted * number of pages. */ if (vm_swap_enabled && page_shortage > 0) vm_req_vmdaemon(VM_SWAP_NORMAL); #endif /* * Wakeup the sync daemon if we skipped a vnode in a writeable object * and we didn't cache or free enough pages. */ if (vnodes_skipped > 0 && page_shortage > cnt.v_free_target - cnt.v_free_min) (void)speedup_syncer(); /* * Compute the number of pages we want to try to move from the * active queue to the inactive queue. */ page_shortage = cnt.v_inactive_target - cnt.v_inactive_count + vm_paging_target() + deficit + addl_page_shortage; pq = &vmd->vmd_pagequeues[PQ_ACTIVE]; vm_pagequeue_lock(pq); maxscan = pq->pq_cnt; /* * If we're just idle polling attempt to visit every * active page within 'update_period' seconds. */ if (pass == 0 && vm_pageout_update_period != 0) { maxscan /= vm_pageout_update_period; page_shortage = maxscan; } /* * Scan the active queue for things we can deactivate. We nominally * track the per-page activity counter and use it to locate * deactivation candidates. */ m = TAILQ_FIRST(&pq->pq_pl); while (m != NULL && maxscan-- > 0 && page_shortage > 0) { KASSERT(m->queue == PQ_ACTIVE, ("vm_pageout_scan: page %p isn't active", m)); next = TAILQ_NEXT(m, plinks.q); if ((m->flags & PG_MARKER) != 0) { m = next; continue; } KASSERT((m->flags & PG_FICTITIOUS) == 0, ("Fictitious page %p cannot be in active queue", m)); KASSERT((m->oflags & VPO_UNMANAGED) == 0, ("Unmanaged page %p cannot be in active queue", m)); if (!vm_pageout_page_lock(m, &next)) { vm_page_unlock(m); m = next; continue; } /* * The count for pagedaemon pages is done after checking the * page for eligibility... */ PCPU_INC(cnt.v_pdpages); /* * Check to see "how much" the page has been used. */ act_delta = 0; if (m->aflags & PGA_REFERENCED) { vm_page_aflag_clear(m, PGA_REFERENCED); act_delta += 1; } /* * Unlocked object ref count check. Two races are possible. * 1) The ref was transitioning to zero and we saw non-zero, * the pmap bits will be checked unnecessarily. * 2) The ref was transitioning to one and we saw zero. * The page lock prevents a new reference to this page so * we need not check the reference bits. */ if (m->object->ref_count != 0) act_delta += pmap_ts_referenced(m); /* * Advance or decay the act_count based on recent usage. */ if (act_delta) { 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); act_delta = m->act_count; } /* * Move this page to the tail of the active or inactive * queue depending on usage. */ if (act_delta == 0) { /* Dequeue to avoid later lock recursion. */ vm_page_dequeue_locked(m); vm_page_deactivate(m); page_shortage--; } else vm_page_requeue_locked(m); vm_page_unlock(m); m = next; } vm_pagequeue_unlock(pq); #if !defined(NO_SWAPPING) /* * Idle process swapout -- run once per second. */ if (vm_swap_idle_enabled) { static long lsec; if (time_second != lsec) { vm_req_vmdaemon(VM_SWAP_IDLE); lsec = time_second; } } #endif /* * If we are critically low on one of RAM or swap and low on * the other, kill the largest process. However, we avoid * doing this on the first pass in order to give ourselves a * chance to flush out dirty vnode-backed pages and to allow * active pages to be moved to the inactive queue and reclaimed. */ vm_pageout_mightbe_oom(vmd, pass); } static int vm_pageout_oom_vote; /* * The pagedaemon threads randlomly select one to perform the * OOM. Trying to kill processes before all pagedaemons * failed to reach free target is premature. */ static void vm_pageout_mightbe_oom(struct vm_domain *vmd, int pass) { int old_vote; if (pass <= 1 || !((swap_pager_avail < 64 && vm_page_count_min()) || (swap_pager_full && vm_paging_target() > 0))) { if (vmd->vmd_oom) { vmd->vmd_oom = FALSE; atomic_subtract_int(&vm_pageout_oom_vote, 1); } return; } if (vmd->vmd_oom) return; vmd->vmd_oom = TRUE; old_vote = atomic_fetchadd_int(&vm_pageout_oom_vote, 1); if (old_vote != vm_ndomains - 1) return; /* * The current pagedaemon thread is the last in the quorum to * start OOM. Initiate the selection and signaling of the * victim. */ vm_pageout_oom(VM_OOM_MEM); /* * After one round of OOM terror, recall our vote. On the * next pass, current pagedaemon would vote again if the low * memory condition is still there, due to vmd_oom being * false. */ vmd->vmd_oom = FALSE; atomic_subtract_int(&vm_pageout_oom_vote, 1); } void vm_pageout_oom(int shortage) { struct proc *p, *bigproc; vm_offset_t size, bigsize; struct thread *td; struct vmspace *vm; /* * We keep the process bigproc locked once we find it to keep anyone * from messing with it; however, there is a possibility of * deadlock if process B is bigproc and one of it's child processes * attempts to propagate a signal to B while we are waiting for A's * lock while walking this list. To avoid this, we don't block on * the process lock but just skip a process if it is already locked. */ bigproc = NULL; bigsize = 0; sx_slock(&allproc_lock); FOREACH_PROC_IN_SYSTEM(p) { int breakout; 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)) { 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(p); if (!vm_map_trylock_read(&vm->vm_map)) { _PRELE(p); PROC_UNLOCK(p); vmspace_free(vm); continue; } PROC_UNLOCK(p); size = vmspace_swap_count(vm); vm_map_unlock_read(&vm->vm_map); if (shortage == VM_OOM_MEM) size += vmspace_resident_count(vm); vmspace_free(vm); /* * if the this process is bigger than the biggest one * remember it. */ if (size > bigsize) { if (bigproc != NULL) PRELE(bigproc); bigproc = p; bigsize = size; } else { PRELE(p); } } sx_sunlock(&allproc_lock); if (bigproc != NULL) { PROC_LOCK(bigproc); killproc(bigproc, "out of swap space"); sched_nice(bigproc, PRIO_MIN); _PRELE(bigproc); PROC_UNLOCK(bigproc); wakeup(&cnt.v_free_count); } } static void vm_pageout_worker(void *arg) { struct vm_domain *domain; int domidx; domidx = (uintptr_t)arg; domain = &vm_dom[domidx]; /* * XXXKIB It could be useful to bind pageout daemon threads to * the cores belonging to the domain, from which vm_page_array * is allocated. */ KASSERT(domain->vmd_segs != 0, ("domain without segments")); vm_pageout_init_marker(&domain->vmd_marker, PQ_INACTIVE); /* * The pageout daemon worker is never done, so loop forever. */ while (TRUE) { /* * If we have enough free memory, wakeup waiters. Do * not clear vm_pages_needed until we reach our target, * otherwise we may be woken up over and over again and * waste a lot of cpu. */ mtx_lock(&vm_page_queue_free_mtx); if (vm_pages_needed && !vm_page_count_min()) { if (!vm_paging_needed()) vm_pages_needed = 0; wakeup(&cnt.v_free_count); } if (vm_pages_needed) { /* * Still not done, take a second pass without waiting * (unlimited dirty cleaning), otherwise sleep a bit * and try again. */ if (domain->vmd_pass > 1) msleep(&vm_pages_needed, &vm_page_queue_free_mtx, PVM, "psleep", hz / 2); } else { /* * Good enough, sleep until required to refresh * stats. */ domain->vmd_pass = 0; msleep(&vm_pages_needed, &vm_page_queue_free_mtx, PVM, "psleep", hz); } if (vm_pages_needed) { cnt.v_pdwakeups++; domain->vmd_pass++; } mtx_unlock(&vm_page_queue_free_mtx); vm_pageout_scan(domain, domain->vmd_pass); } } /* * vm_pageout_init initialises basic pageout daemon settings. */ static void vm_pageout_init(void) { /* * Initialize some paging parameters. */ cnt.v_interrupt_free_min = 2; if (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 (cnt.v_page_count > 1024) cnt.v_free_min = 4 + (cnt.v_page_count - 1024) / 200; else cnt.v_free_min = 4; cnt.v_pageout_free_min = (2*MAXBSIZE)/PAGE_SIZE + cnt.v_interrupt_free_min; cnt.v_free_reserved = vm_pageout_page_count + cnt.v_pageout_free_min + (cnt.v_page_count / 768); cnt.v_free_severe = cnt.v_free_min / 2; cnt.v_free_target = 4 * cnt.v_free_min + cnt.v_free_reserved; cnt.v_free_min += cnt.v_free_reserved; cnt.v_free_severe += cnt.v_free_reserved; cnt.v_inactive_target = (3 * cnt.v_free_target) / 2; if (cnt.v_inactive_target > cnt.v_free_count / 3) cnt.v_inactive_target = 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 = (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 = cnt.v_free_count / 3; } /* * vm_pageout is the high level pageout daemon. */ static void vm_pageout(void) { #if MAXMEMDOM > 1 int error, i; #endif swap_pager_swap_init(); #if MAXMEMDOM > 1 for (i = 1; i < vm_ndomains; i++) { error = kthread_add(vm_pageout_worker, (void *)(uintptr_t)i, curproc, NULL, 0, 0, "dom%d", i); if (error != 0) { panic("starting pageout for domain %d, error %d\n", i, error); } } #endif vm_pageout_worker((void *)(uintptr_t)0); } /* * Unless the free page queue lock is held by the caller, this function * should be regarded as advisory. Specifically, the caller should * not msleep() on &cnt.v_free_count following this function unless * the free page queue lock is held until the msleep() is performed. */ void pagedaemon_wakeup(void) { if (!vm_pages_needed && curthread->td_proc != pageproc) { vm_pages_needed = 1; wakeup(&vm_pages_needed); } } #if !defined(NO_SWAPPING) static void vm_req_vmdaemon(int req) { static int lastrun = 0; mtx_lock(&vm_daemon_mtx); vm_pageout_req_swapout |= req; if ((ticks > (lastrun + hz)) || (ticks < lastrun)) { wakeup(&vm_daemon_needed); lastrun = ticks; } mtx_unlock(&vm_daemon_mtx); } static void vm_daemon(void) { struct rlimit rsslim; struct proc *p; struct thread *td; struct vmspace *vm; int breakout, swapout_flags, tryagain, attempts; #ifdef RACCT uint64_t rsize, ravailable; #endif while (TRUE) { mtx_lock(&vm_daemon_mtx); #ifdef RACCT msleep(&vm_daemon_needed, &vm_daemon_mtx, PPAUSE, "psleep", hz); #else msleep(&vm_daemon_needed, &vm_daemon_mtx, PPAUSE, "psleep", 0); #endif swapout_flags = vm_pageout_req_swapout; vm_pageout_req_swapout = 0; mtx_unlock(&vm_daemon_mtx); if (swapout_flags) swapout_procs(swapout_flags); /* * scan the processes for exceeding their rlimits or if * process is swapped out -- deactivate pages */ tryagain = 0; attempts = 0; again: attempts++; sx_slock(&allproc_lock); FOREACH_PROC_IN_SYSTEM(p) { vm_pindex_t limit, size; /* * if this is a system process or if we have already * looked at this process, skip it. */ PROC_LOCK(p); if (p->p_state != PRS_NORMAL || p->p_flag & (P_INEXEC | P_SYSTEM | P_WEXIT)) { PROC_UNLOCK(p); continue; } /* * if the process is in a non-running type state, * don't touch it. */ breakout = 0; FOREACH_THREAD_IN_PROC(p, td) { thread_lock(td); if (!TD_ON_RUNQ(td) && !TD_IS_RUNNING(td) && !TD_IS_SLEEPING(td) && !TD_IS_SUSPENDED(td)) { thread_unlock(td); breakout = 1; break; } thread_unlock(td); } if (breakout) { PROC_UNLOCK(p); continue; } /* * get a limit */ lim_rlimit(p, RLIMIT_RSS, &rsslim); limit = OFF_TO_IDX( qmin(rsslim.rlim_cur, rsslim.rlim_max)); /* * let processes that are swapped out really be * swapped out set the limit to nothing (will force a * swap-out.) */ if ((p->p_flag & P_INMEM) == 0) limit = 0; /* XXX */ vm = vmspace_acquire_ref(p); PROC_UNLOCK(p); if (vm == NULL) continue; size = vmspace_resident_count(vm); if (size >= limit) { vm_pageout_map_deactivate_pages( &vm->vm_map, limit); } #ifdef RACCT rsize = IDX_TO_OFF(size); PROC_LOCK(p); racct_set(p, RACCT_RSS, rsize); ravailable = racct_get_available(p, RACCT_RSS); PROC_UNLOCK(p); if (rsize > ravailable) { /* * Don't be overly aggressive; this might be * an innocent process, and the limit could've * been exceeded by some memory hog. Don't * try to deactivate more than 1/4th of process' * resident set size. */ if (attempts <= 8) { if (ravailable < rsize - (rsize / 4)) ravailable = rsize - (rsize / 4); } vm_pageout_map_deactivate_pages( &vm->vm_map, OFF_TO_IDX(ravailable)); /* Update RSS usage after paging out. */ size = vmspace_resident_count(vm); rsize = IDX_TO_OFF(size); PROC_LOCK(p); racct_set(p, RACCT_RSS, rsize); PROC_UNLOCK(p); if (rsize > ravailable) tryagain = 1; } #endif vmspace_free(vm); } sx_sunlock(&allproc_lock); if (tryagain != 0 && attempts <= 10) goto again; } } #endif /* !defined(NO_SWAPPING) */