/* * 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. * * 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. * * $Id: vm_pageout.c,v 1.133 1999/01/24 01:33:22 dillon Exp $ */ /* * The proverbial page-out daemon. */ #include "opt_vm.h" #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 __P((void)); static int vm_pageout_clean __P((vm_page_t)); static int vm_pageout_scan __P((void)); static int vm_pageout_free_page_calc __P((vm_size_t count)); struct proc *pageproc; static struct kproc_desc page_kp = { "pagedaemon", vm_pageout, &pageproc }; SYSINIT_KT(pagedaemon, SI_SUB_KTHREAD_PAGE, SI_ORDER_FIRST, kproc_start, &page_kp) #if !defined(NO_SWAPPING) /* the kernel process "vm_daemon"*/ static void vm_daemon __P((void)); static struct proc *vmproc; static struct kproc_desc vm_kp = { "vmdaemon", vm_daemon, &vmproc }; SYSINIT_KT(vmdaemon, SI_SUB_KTHREAD_VM, SI_ORDER_FIRST, kproc_start, &vm_kp) #endif int vm_pages_needed=0; /* Event on which pageout daemon sleeps */ int vm_pageout_deficit=0; /* Estimated number of pages deficit */ int vm_pageout_pages_needed=0; /* flag saying that the pageout daemon needs pages */ extern int npendingio; #if !defined(NO_SWAPPING) static int vm_pageout_req_swapout; /* XXX */ static int vm_daemon_needed; #endif extern int nswiodone; extern int vm_swap_size; extern int vfs_update_wakeup; static int vm_pageout_stats_max=0, vm_pageout_stats_interval = 0; static int vm_pageout_full_stats_interval = 0; static int vm_pageout_stats_free_max=0, vm_pageout_algorithm_lru=0; static int defer_swap_pageouts=0; static int disable_swap_pageouts=0; static int max_page_launder=100; #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, VM_PAGEOUT_ALGORITHM, pageout_algorithm, CTLFLAG_RW, &vm_pageout_algorithm_lru, 0, "LRU page mgmt"); SYSCTL_INT(_vm, OID_AUTO, pageout_stats_max, CTLFLAG_RW, &vm_pageout_stats_max, 0, "Max pageout stats scan length"); SYSCTL_INT(_vm, OID_AUTO, pageout_full_stats_interval, CTLFLAG_RW, &vm_pageout_full_stats_interval, 0, "Interval for full stats scan"); SYSCTL_INT(_vm, OID_AUTO, pageout_stats_interval, CTLFLAG_RW, &vm_pageout_stats_interval, 0, "Interval for partial stats scan"); SYSCTL_INT(_vm, OID_AUTO, pageout_stats_free_max, CTLFLAG_RW, &vm_pageout_stats_free_max, 0, "Not implemented"); #if defined(NO_SWAPPING) SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled, CTLFLAG_RD, &vm_swap_enabled, 0, ""); SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled, CTLFLAG_RD, &vm_swap_idle_enabled, 0, ""); #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"); SYSCTL_INT(_vm, OID_AUTO, max_page_launder, CTLFLAG_RW, &max_page_launder, 0, "Maximum number of pages to clean per pass"); #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 */ #if !defined(NO_SWAPPING) typedef void freeer_fcn_t __P((vm_map_t, vm_object_t, vm_pindex_t, int)); static void vm_pageout_map_deactivate_pages __P((vm_map_t, vm_pindex_t)); static freeer_fcn_t vm_pageout_object_deactivate_pages; static void vm_req_vmdaemon __P((void)); #endif static void vm_pageout_page_stats(void); void pmap_collect(void); /* * 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(m) vm_page_t m; { register vm_object_t object; vm_page_t mc[2*vm_pageout_page_count]; int pageout_count; int i, forward_okay, backward_okay, page_base; vm_pindex_t pindex = m->pindex; object = m->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. */ #if 0 /* * If not OBJT_SWAP, additional memory may be needed to do the pageout. * Try to avoid the deadlock. */ if ((object->type == OBJT_DEFAULT) && ((cnt.v_free_count + cnt.v_cache_count) < cnt.v_pageout_free_min)) return 0; #endif /* * Don't mess with the page if it's busy. */ if ((m->hold_count != 0) || ((m->busy != 0) || (m->flags & PG_BUSY))) return 0; #if 0 /* * XXX REMOVED XXX. vm_object_collapse() can block, which can * change the page state. Calling vm_object_collapse() might also * destroy or rename the page because we have not busied it yet!!! * So this code segment is removed. */ /* * Try collapsing before it's too late. XXX huh? Why are we doing * this here? */ if (object->backing_object) { vm_object_collapse(object); } #endif mc[vm_pageout_page_count] = m; pageout_count = 1; page_base = vm_pageout_page_count; forward_okay = TRUE; if (pindex != 0) backward_okay = TRUE; else backward_okay = FALSE; /* * 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. */ for (i = 1; (i < vm_pageout_page_count) && (forward_okay || backward_okay); i++) { vm_page_t p; /* * See if forward page is clusterable. */ if (forward_okay) { /* * Stop forward scan at end of object. */ if ((pindex + i) > object->size) { forward_okay = FALSE; goto do_backward; } p = vm_page_lookup(object, pindex + i); if (p) { if (((p->queue - p->pc) == PQ_CACHE) || (p->flags & PG_BUSY) || p->busy) { forward_okay = FALSE; goto do_backward; } vm_page_test_dirty(p); if ((p->dirty & p->valid) != 0 && (p->queue == PQ_INACTIVE) && (p->wire_count == 0) && (p->hold_count == 0)) { mc[vm_pageout_page_count + i] = p; pageout_count++; if (pageout_count == vm_pageout_page_count) break; } else { forward_okay = FALSE; } } else { forward_okay = FALSE; } } do_backward: /* * See if backward page is clusterable. */ if (backward_okay) { /* * Stop backward scan at beginning of object. */ if ((pindex - i) == 0) { backward_okay = FALSE; } p = vm_page_lookup(object, pindex - i); if (p) { if (((p->queue - p->pc) == PQ_CACHE) || (p->flags & PG_BUSY) || p->busy) { backward_okay = FALSE; continue; } vm_page_test_dirty(p); if ((p->dirty & p->valid) != 0 && (p->queue == PQ_INACTIVE) && (p->wire_count == 0) && (p->hold_count == 0)) { mc[vm_pageout_page_count - i] = p; pageout_count++; page_base--; if (pageout_count == vm_pageout_page_count) break; } else { backward_okay = FALSE; } } else { backward_okay = FALSE; } } } /* * we allow reads during pageouts... */ return vm_pageout_flush(&mc[page_base], pageout_count, 0); } /* * 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. */ int vm_pageout_flush(mc, count, flags) vm_page_t *mc; int count; int flags; { register vm_object_t object; int pageout_status[count]; int numpagedout = 0; int i; /* * 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. */ for (i = 0; i < count; i++) { vm_page_io_start(mc[i]); vm_page_protect(mc[i], VM_PROT_READ); } object = mc[0]->object; vm_object_pip_add(object, count); vm_pager_put_pages(object, mc, count, (flags | ((object == kernel_object) ? OBJPC_SYNC : 0)), pageout_status); for (i = 0; i < count; i++) { vm_page_t mt = mc[i]; switch (pageout_status[i]) { case VM_PAGER_OK: numpagedout++; break; 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. */ pmap_clear_modify(VM_PAGE_TO_PHYS(mt)); mt->dirty = 0; 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_activate(mt); break; case VM_PAGER_AGAIN: 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_io_finish(mt); } } return numpagedout; } #if !defined(NO_SWAPPING) /* * vm_pageout_object_deactivate_pages * * deactivate enough pages to satisfy the inactive target * requirements or if vm_page_proc_limit is set, then * deactivate all of the pages in the object and its * backing_objects. * * The object and map must be locked. */ static void vm_pageout_object_deactivate_pages(map, object, desired, map_remove_only) vm_map_t map; vm_object_t object; vm_pindex_t desired; int map_remove_only; { register vm_page_t p, next; int rcount; int remove_mode; int s; if (object->type == OBJT_DEVICE) return; while (object) { if (vm_map_pmap(map)->pm_stats.resident_count <= desired) return; if (object->paging_in_progress) return; remove_mode = map_remove_only; if (object->shadow_count > 1) remove_mode = 1; /* * scan the objects entire memory queue */ rcount = object->resident_page_count; p = TAILQ_FIRST(&object->memq); while (p && (rcount-- > 0)) { int actcount; if (vm_map_pmap(map)->pm_stats.resident_count <= desired) return; next = TAILQ_NEXT(p, listq); cnt.v_pdpages++; if (p->wire_count != 0 || p->hold_count != 0 || p->busy != 0 || (p->flags & PG_BUSY) || !pmap_page_exists(vm_map_pmap(map), VM_PAGE_TO_PHYS(p))) { p = next; continue; } actcount = pmap_ts_referenced(VM_PAGE_TO_PHYS(p)); if (actcount) { vm_page_flag_set(p, PG_REFERENCED); } else if (p->flags & PG_REFERENCED) { actcount = 1; } if ((p->queue != PQ_ACTIVE) && (p->flags & PG_REFERENCED)) { vm_page_activate(p); p->act_count += actcount; vm_page_flag_clear(p, PG_REFERENCED); } else if (p->queue == PQ_ACTIVE) { if ((p->flags & PG_REFERENCED) == 0) { p->act_count -= min(p->act_count, ACT_DECLINE); if (!remove_mode && (vm_pageout_algorithm_lru || (p->act_count == 0))) { vm_page_protect(p, VM_PROT_NONE); vm_page_deactivate(p); } else { s = splvm(); TAILQ_REMOVE(&vm_page_queue_active, p, pageq); TAILQ_INSERT_TAIL(&vm_page_queue_active, p, pageq); splx(s); } } else { vm_page_activate(p); vm_page_flag_clear(p, PG_REFERENCED); if (p->act_count < (ACT_MAX - ACT_ADVANCE)) p->act_count += ACT_ADVANCE; s = splvm(); TAILQ_REMOVE(&vm_page_queue_active, p, pageq); TAILQ_INSERT_TAIL(&vm_page_queue_active, p, pageq); splx(s); } } else if (p->queue == PQ_INACTIVE) { vm_page_protect(p, VM_PROT_NONE); } p = next; } object = object->backing_object; } return; } /* * 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; vm_pindex_t desired; { vm_map_entry_t tmpe; vm_object_t obj, bigobj; if (lockmgr(&map->lock, LK_EXCLUSIVE | LK_NOWAIT, (void *)0, curproc)) { return; } bigobj = NULL; /* * 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_A_MAP|MAP_ENTRY_IS_SUB_MAP)) == 0) { obj = tmpe->object.vm_object; if ((obj != NULL) && (obj->shadow_count <= 1) && ((bigobj == NULL) || (bigobj->resident_page_count < obj->resident_page_count))) { bigobj = obj; } } tmpe = tmpe->next; } if (bigobj) vm_pageout_object_deactivate_pages(map, bigobj, desired, 0); /* * 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 (vm_map_pmap(map)->pm_stats.resident_count <= desired) break; if ((tmpe->eflags & (MAP_ENTRY_IS_A_MAP|MAP_ENTRY_IS_SUB_MAP)) == 0) { obj = tmpe->object.vm_object; if (obj) vm_pageout_object_deactivate_pages(map, obj, desired, 0); } tmpe = tmpe->next; }; /* * Remove all mappings if a process is swapped out, this will free page * table pages. */ if (desired == 0) pmap_remove(vm_map_pmap(map), VM_MIN_ADDRESS, VM_MAXUSER_ADDRESS); vm_map_unlock(map); return; } #endif /* * Don't try to be fancy - being fancy can lead to VOP_LOCK's and therefore * to vnode deadlocks. We only do it for OBJT_DEFAULT and OBJT_SWAP objects * which we know can be trivially freed. */ void vm_pageout_page_free(vm_page_t m) { vm_object_t object = m->object; int type = object->type; if (type == OBJT_SWAP || type == OBJT_DEFAULT) vm_object_reference(object); vm_page_busy(m); vm_page_protect(m, VM_PROT_NONE); vm_page_free(m); if (type == OBJT_SWAP || type == OBJT_DEFAULT) vm_object_deallocate(object); } /* * vm_pageout_scan does the dirty work for the pageout daemon. */ static int vm_pageout_scan() { vm_page_t m, next; int page_shortage, maxscan, pcount; int addl_page_shortage, addl_page_shortage_init; int maxlaunder; int launder_loop = 0; struct proc *p, *bigproc; vm_offset_t size, bigsize; vm_object_t object; int force_wakeup = 0; int actcount; int vnodes_skipped = 0; int s; /* * Do whatever cleanup that the pmap code can. */ pmap_collect(); addl_page_shortage_init = vm_pageout_deficit; vm_pageout_deficit = 0; if (max_page_launder == 0) max_page_launder = 1; /* * Calculate the number of pages we want to either free or move * to the cache. */ page_shortage = (cnt.v_free_target + cnt.v_cache_min) - (cnt.v_free_count + cnt.v_cache_count); page_shortage += addl_page_shortage_init; /* * Figure out what to do with dirty pages when they are encountered. * Assume that 1/3 of the pages on the inactive list are clean. If * we think we can reach our target, disable laundering (do not * clean any dirty pages). If we miss the target we will loop back * up and do a laundering run. */ if (cnt.v_inactive_count / 3 > page_shortage) { maxlaunder = 0; launder_loop = 0; } else { maxlaunder = (cnt.v_inactive_target > max_page_launder) ? max_page_launder : cnt.v_inactive_target; launder_loop = 1; } /* * 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. */ rescan0: addl_page_shortage = addl_page_shortage_init; maxscan = cnt.v_inactive_count; for ( m = TAILQ_FIRST(&vm_page_queue_inactive); m != NULL && maxscan-- > 0 && page_shortage > 0; m = next ) { cnt.v_pdpages++; if (m->queue != PQ_INACTIVE) { goto rescan0; } next = TAILQ_NEXT(m, pageq); if (m->hold_count) { s = splvm(); TAILQ_REMOVE(&vm_page_queue_inactive, m, pageq); TAILQ_INSERT_TAIL(&vm_page_queue_inactive, m, pageq); splx(s); addl_page_shortage++; continue; } /* * Dont mess with busy pages, keep in the front of the * queue, most likely are being paged out. */ if (m->busy || (m->flags & PG_BUSY)) { addl_page_shortage++; continue; } /* * If the object is not being used, we ignore previous * references. */ if (m->object->ref_count == 0) { vm_page_flag_clear(m, PG_REFERENCED); pmap_clear_reference(VM_PAGE_TO_PHYS(m)); /* * Otherwise, if the page has been referenced while in the * inactive queue, we bump the "activation count" upwards, * making 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. */ } else if (((m->flags & PG_REFERENCED) == 0) && (actcount = pmap_ts_referenced(VM_PAGE_TO_PHYS(m)))) { vm_page_activate(m); m->act_count += (actcount + ACT_ADVANCE); continue; } /* * If the upper level VM system knows about any page * references, we activate the page. We also set the * "activation count" higher than normal so that we will less * likely place pages back onto the inactive queue again. */ if ((m->flags & PG_REFERENCED) != 0) { vm_page_flag_clear(m, PG_REFERENCED); actcount = pmap_ts_referenced(VM_PAGE_TO_PHYS(m)); vm_page_activate(m); m->act_count += (actcount + ACT_ADVANCE + 1); continue; } /* * If the upper level VM system doesn't know anything about * the page being dirty, we have to check for it again. As * far as the VM code knows, any partially dirty pages are * fully dirty. */ if (m->dirty == 0) { vm_page_test_dirty(m); } else { vm_page_dirty(m); } /* * Invalid pages can be easily freed */ if (m->valid == 0) { vm_pageout_page_free(m); cnt.v_dfree++; --page_shortage; /* * Clean pages can be placed onto the cache queue. */ } else if (m->dirty == 0) { vm_page_cache(m); --page_shortage; /* * Dirty pages need to be paged out. Note that we clean * only a limited number of pages per pagedaemon pass. */ } else if (maxlaunder > 0) { int written; int swap_pageouts_ok; struct vnode *vp = NULL; object = m->object; 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 && (cnt.v_free_count + cnt.v_cache_count) < cnt.v_free_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)) { s = splvm(); TAILQ_REMOVE(&vm_page_queue_inactive, m, pageq); TAILQ_INSERT_TAIL(&vm_page_queue_inactive, m, pageq); splx(s); continue; } /* * For now we protect against potential memory * deadlocks by requiring significant memory to be * free if the object is not OBJT_DEFAULT or OBJT_SWAP. * We do not 'trust' any other object type to operate * with low memory, not even OBJT_DEVICE. The VM * allocator will special case allocations done by * the pageout daemon so the check below actually * does have some hysteresis in it. It isn't the best * solution, though. */ if ( object->type != OBJT_DEFAULT && object->type != OBJT_SWAP && cnt.v_free_count < cnt.v_free_reserved ) { s = splvm(); TAILQ_REMOVE(&vm_page_queue_inactive, m, pageq); TAILQ_INSERT_TAIL(&vm_page_queue_inactive, m, pageq); splx(s); continue; } /* * Presumably we have sufficient free memory to do * the more sophisticated checks and locking required * for vnodes. * * The object is already known NOT to be dead. The * vget() may still block, though, because * VOP_ISLOCKED() doesn't check to see if an inode * (v_data) is associated with the vnode. If it isn't, * vget() will load in it from disk. Worse, vget() * may actually get stuck waiting on "inode" if another * process is in the process of bringing the inode in. * This is bad news for us either way. * * So for the moment we check v_data == NULL as a * workaround. This means that vnodes which do not * use v_data in the way we expect probably will not * wind up being paged out by the pager and it will be * up to the syncer to get them. That's better then * us blocking here. * * This whole code section is bogus - we need to fix * the vnode pager to handle vm_page_t's without us * having to do any sophisticated VOP tests. */ if (object->type == OBJT_VNODE) { vp = object->handle; if (VOP_ISLOCKED(vp) || vp->v_data == NULL || vget(vp, LK_EXCLUSIVE|LK_NOOBJ, curproc)) { if ((m->queue == PQ_INACTIVE) && (m->hold_count == 0) && (m->busy == 0) && (m->flags & PG_BUSY) == 0) { s = splvm(); TAILQ_REMOVE(&vm_page_queue_inactive, m, pageq); TAILQ_INSERT_TAIL(&vm_page_queue_inactive, m, pageq); splx(s); } if (object->flags & OBJ_MIGHTBEDIRTY) vnodes_skipped++; continue; } /* * The page might have been moved to another queue * during potential blocking in vget() above. */ if (m->queue != PQ_INACTIVE) { if (object->flags & OBJ_MIGHTBEDIRTY) vnodes_skipped++; vput(vp); continue; } /* * The page may have been busied during the blocking in * vput(); We don't move the page back onto the end of * the queue so that statistics are more correct if we don't. */ if (m->busy || (m->flags & PG_BUSY)) { vput(vp); continue; } /* * If the page has become held, then skip it */ if (m->hold_count) { s = splvm(); TAILQ_REMOVE(&vm_page_queue_inactive, m, pageq); TAILQ_INSERT_TAIL(&vm_page_queue_inactive, m, pageq); splx(s); if (object->flags & OBJ_MIGHTBEDIRTY) vnodes_skipped++; vput(vp); continue; } } /* * 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. */ written = vm_pageout_clean(m); if (vp) vput(vp); maxlaunder -= written; } } /* * If we still have a page shortage and we didn't launder anything, * run the inactive scan again and launder something this time. */ if (launder_loop == 0 && page_shortage > 0) { launder_loop = 1; maxlaunder = (cnt.v_inactive_target > max_page_launder) ? max_page_launder : cnt.v_inactive_target; goto rescan0; } /* * Compute the page shortage from the point of view of having to * move pages from the active queue to the inactive queue. */ page_shortage = (cnt.v_inactive_target + cnt.v_cache_min) - (cnt.v_free_count + cnt.v_inactive_count + cnt.v_cache_count); page_shortage += addl_page_shortage; /* * Scan the active queue for things we can deactivate */ pcount = cnt.v_active_count; m = TAILQ_FIRST(&vm_page_queue_active); while ((m != NULL) && (pcount-- > 0) && (page_shortage > 0)) { /* * This is a consistancy check, and should likely be a panic * or warning. */ if (m->queue != PQ_ACTIVE) { break; } next = TAILQ_NEXT(m, pageq); /* * Don't deactivate pages that are busy. */ if ((m->busy != 0) || (m->flags & PG_BUSY) || (m->hold_count != 0)) { s = splvm(); TAILQ_REMOVE(&vm_page_queue_active, m, pageq); TAILQ_INSERT_TAIL(&vm_page_queue_active, m, pageq); splx(s); m = next; continue; } /* * The count for pagedaemon pages is done after checking the * page for eligbility... */ cnt.v_pdpages++; /* * Check to see "how much" the page has been used. */ actcount = 0; if (m->object->ref_count != 0) { if (m->flags & PG_REFERENCED) { actcount += 1; } actcount += pmap_ts_referenced(VM_PAGE_TO_PHYS(m)); if (actcount) { m->act_count += ACT_ADVANCE + actcount; if (m->act_count > ACT_MAX) m->act_count = ACT_MAX; } } /* * Since we have "tested" this bit, we need to clear it now. */ vm_page_flag_clear(m, PG_REFERENCED); /* * Only if an object is currently being used, do we use the * page activation count stats. */ if (actcount && (m->object->ref_count != 0)) { s = splvm(); TAILQ_REMOVE(&vm_page_queue_active, m, pageq); TAILQ_INSERT_TAIL(&vm_page_queue_active, m, pageq); splx(s); } else { m->act_count -= min(m->act_count, ACT_DECLINE); if (vm_pageout_algorithm_lru || (m->object->ref_count == 0) || (m->act_count == 0)) { page_shortage--; if (m->object->ref_count == 0) { vm_page_protect(m, VM_PROT_NONE); if (m->dirty == 0) vm_page_cache(m); else vm_page_deactivate(m); } else { vm_page_deactivate(m); } } else { s = splvm(); TAILQ_REMOVE(&vm_page_queue_active, m, pageq); TAILQ_INSERT_TAIL(&vm_page_queue_active, m, pageq); splx(s); } } m = next; } s = splvm(); /* * We try to maintain some *really* free pages, this allows interrupt * code to be guaranteed space. Since both cache and free queues * are considered basically 'free', moving pages from cache to free * does not effect other calculations. */ while (cnt.v_free_count < cnt.v_free_reserved) { static int cache_rover = 0; m = vm_page_list_find(PQ_CACHE, cache_rover); if (!m) break; if ((m->flags & PG_BUSY) || m->busy || m->hold_count || m->wire_count) { #ifdef INVARIANTS printf("Warning: busy page %p found in cache\n", m); #endif vm_page_deactivate(m); continue; } cache_rover = (cache_rover + PQ_PRIME2) & PQ_L2_MASK; vm_pageout_page_free(m); cnt.v_dfree++; } splx(s); #if !defined(NO_SWAPPING) /* * Idle process swapout -- run once per second. */ if (vm_swap_idle_enabled) { static long lsec; if (time_second != lsec) { vm_pageout_req_swapout |= VM_SWAP_IDLE; vm_req_vmdaemon(); lsec = time_second; } } #endif /* * If we didn't get enough free pages, and we have skipped a vnode * in a writeable object, wakeup the sync daemon. And kick swapout * if we did not get enough free pages. */ if ((cnt.v_cache_count + cnt.v_free_count) < (cnt.v_free_target + cnt.v_cache_min) ) { if (vnodes_skipped && (cnt.v_cache_count + cnt.v_free_count) < cnt.v_free_min) { if (!vfs_update_wakeup) { vfs_update_wakeup = 1; wakeup(&vfs_update_wakeup); } } #if !defined(NO_SWAPPING) if (vm_swap_enabled && (cnt.v_free_count + cnt.v_cache_count < cnt.v_free_target)) { vm_req_vmdaemon(); vm_pageout_req_swapout |= VM_SWAP_NORMAL; } #endif } /* * make sure that we have swap space -- if we are low on memory and * swap -- then kill the biggest process. */ if ((vm_swap_size == 0 || swap_pager_full) && ((cnt.v_free_count + cnt.v_cache_count) < cnt.v_free_min)) { bigproc = NULL; bigsize = 0; for (p = allproc.lh_first; p != 0; p = p->p_list.le_next) { /* * if this is a system process, skip it */ if ((p->p_flag & P_SYSTEM) || (p->p_pid == 1) || ((p->p_pid < 48) && (vm_swap_size != 0))) { continue; } /* * if the process is in a non-running type state, * don't touch it. */ if (p->p_stat != SRUN && p->p_stat != SSLEEP) { continue; } /* * get the process size */ size = p->p_vmspace->vm_pmap.pm_stats.resident_count; /* * if the this process is bigger than the biggest one * remember it. */ if (size > bigsize) { bigproc = p; bigsize = size; } } if (bigproc != NULL) { killproc(bigproc, "out of swap space"); bigproc->p_estcpu = 0; bigproc->p_nice = PRIO_MIN; resetpriority(bigproc); wakeup(&cnt.v_free_count); } } return force_wakeup; } /* * This routine tries to maintain the pseudo LRU active queue, * so that during long periods of time where there is no paging, * that some statistic accumlation still occurs. This code * helps the situation where paging just starts to occur. */ static void vm_pageout_page_stats() { int s; vm_page_t m,next; int pcount,tpcount; /* Number of pages to check */ static int fullintervalcount = 0; int page_shortage; page_shortage = (cnt.v_inactive_target + cnt.v_cache_max + cnt.v_free_min) - (cnt.v_free_count + cnt.v_inactive_count + cnt.v_cache_count); if (page_shortage <= 0) return; pcount = cnt.v_active_count; fullintervalcount += vm_pageout_stats_interval; if (fullintervalcount < vm_pageout_full_stats_interval) { tpcount = (vm_pageout_stats_max * cnt.v_active_count) / cnt.v_page_count; if (pcount > tpcount) pcount = tpcount; } m = TAILQ_FIRST(&vm_page_queue_active); while ((m != NULL) && (pcount-- > 0)) { int actcount; if (m->queue != PQ_ACTIVE) { break; } next = TAILQ_NEXT(m, pageq); /* * Don't deactivate pages that are busy. */ if ((m->busy != 0) || (m->flags & PG_BUSY) || (m->hold_count != 0)) { s = splvm(); TAILQ_REMOVE(&vm_page_queue_active, m, pageq); TAILQ_INSERT_TAIL(&vm_page_queue_active, m, pageq); splx(s); m = next; continue; } actcount = 0; if (m->flags & PG_REFERENCED) { vm_page_flag_clear(m, PG_REFERENCED); actcount += 1; } actcount += pmap_ts_referenced(VM_PAGE_TO_PHYS(m)); if (actcount) { m->act_count += ACT_ADVANCE + actcount; if (m->act_count > ACT_MAX) m->act_count = ACT_MAX; s = splvm(); TAILQ_REMOVE(&vm_page_queue_active, m, pageq); TAILQ_INSERT_TAIL(&vm_page_queue_active, m, pageq); splx(s); } else { if (m->act_count == 0) { /* * We turn off page access, so that we have more accurate * RSS stats. We don't do this in the normal page deactivation * when the system is loaded VM wise, because the cost of * the large number of page protect operations would be higher * than the value of doing the operation. */ vm_page_protect(m, VM_PROT_NONE); vm_page_deactivate(m); } else { m->act_count -= min(m->act_count, ACT_DECLINE); s = splvm(); TAILQ_REMOVE(&vm_page_queue_active, m, pageq); TAILQ_INSERT_TAIL(&vm_page_queue_active, m, pageq); splx(s); } } m = next; } } static int vm_pageout_free_page_calc(count) vm_size_t count; { if (count < cnt.v_page_count) return 0; /* * 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 + (count / 768) + PQ_L2_SIZE; cnt.v_free_min += cnt.v_free_reserved; return 1; } /* * vm_pageout is the high level pageout daemon. */ static void vm_pageout() { /* * Initialize some paging parameters. */ cnt.v_interrupt_free_min = 2; if (cnt.v_page_count < 2000) vm_pageout_page_count = 8; vm_pageout_free_page_calc(cnt.v_page_count); /* * free_reserved needs to include enough for the largest swap pager * structures plus enough for any pv_entry structs when paging. */ if (cnt.v_free_count > 6144) cnt.v_free_target = 3 * cnt.v_free_min + cnt.v_free_reserved; else cnt.v_free_target = 2 * cnt.v_free_min + cnt.v_free_reserved; if (cnt.v_free_count > 2048) { cnt.v_cache_min = cnt.v_free_target; cnt.v_cache_max = 2 * cnt.v_cache_min; cnt.v_inactive_target = (3 * cnt.v_free_target) / 2; } else { cnt.v_cache_min = 0; cnt.v_cache_max = 0; cnt.v_inactive_target = cnt.v_free_count / 4; } if (cnt.v_inactive_target > cnt.v_free_count / 3) cnt.v_inactive_target = cnt.v_free_count / 3; /* XXX does not really belong here */ if (vm_page_max_wired == 0) vm_page_max_wired = cnt.v_free_count / 3; if (vm_pageout_stats_max == 0) vm_pageout_stats_max = cnt.v_free_target; /* * Set interval in seconds for stats scan. */ if (vm_pageout_stats_interval == 0) vm_pageout_stats_interval = 5; if (vm_pageout_full_stats_interval == 0) vm_pageout_full_stats_interval = vm_pageout_stats_interval * 4; /* * Set maximum free per pass */ if (vm_pageout_stats_free_max == 0) vm_pageout_stats_free_max = 5; max_page_launder = (cnt.v_page_count > 1800 ? 32 : 16); swap_pager_swap_init(); /* * The pageout daemon is never done, so loop forever. */ while (TRUE) { int error; int s = splvm(); if (!vm_pages_needed || ((cnt.v_free_count + cnt.v_cache_count) > cnt.v_free_min)) { vm_pages_needed = 0; error = tsleep(&vm_pages_needed, PVM, "psleep", vm_pageout_stats_interval * hz); if (error && !vm_pages_needed) { splx(s); vm_pageout_page_stats(); continue; } } else if (vm_pages_needed) { vm_pages_needed = 0; tsleep(&vm_pages_needed, PVM, "psleep", hz/2); } if (vm_pages_needed) cnt.v_pdwakeups++; vm_pages_needed = 0; splx(s); vm_pageout_scan(); vm_pageout_deficit = 0; wakeup(&cnt.v_free_count); } } void pagedaemon_wakeup() { if (!vm_pages_needed && curproc != pageproc) { vm_pages_needed++; wakeup(&vm_pages_needed); } } #if !defined(NO_SWAPPING) static void vm_req_vmdaemon() { static int lastrun = 0; if ((ticks > (lastrun + hz)) || (ticks < lastrun)) { wakeup(&vm_daemon_needed); lastrun = ticks; } } static void vm_daemon() { struct proc *p; while (TRUE) { tsleep(&vm_daemon_needed, PPAUSE, "psleep", 0); if (vm_pageout_req_swapout) { swapout_procs(vm_pageout_req_swapout); vm_pageout_req_swapout = 0; } /* * scan the processes for exceeding their rlimits or if * process is swapped out -- deactivate pages */ for (p = allproc.lh_first; p != 0; p = p->p_list.le_next) { quad_t limit; vm_offset_t size; /* * if this is a system process or if we have already * looked at this process, skip it. */ if (p->p_flag & (P_SYSTEM | P_WEXIT)) { continue; } /* * if the process is in a non-running type state, * don't touch it. */ if (p->p_stat != SRUN && p->p_stat != SSLEEP) { continue; } /* * get a limit */ limit = qmin(p->p_rlimit[RLIMIT_RSS].rlim_cur, p->p_rlimit[RLIMIT_RSS].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 */ size = p->p_vmspace->vm_pmap.pm_stats.resident_count * PAGE_SIZE; if (limit >= 0 && size >= limit) { vm_pageout_map_deactivate_pages(&p->p_vmspace->vm_map, (vm_pindex_t)(limit >> PAGE_SHIFT) ); } } } } #endif