/*- * SPDX-License-Identifier: (BSD-4-Clause AND MIT-CMU) * * 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. */ #include __FBSDID("$FreeBSD$"); #include "opt_kstack_pages.h" #include "opt_kstack_max_pages.h" #include "opt_vm.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 #include #include #include /* 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); static int vm_swap_enabled = 1; static int vm_swap_idle_enabled = 0; 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"); /* * Swap_idle_threshold1 is the guaranteed swapped in time for a process */ static int swap_idle_threshold1 = 2; SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold1, CTLFLAG_RW, &swap_idle_threshold1, 0, "Guaranteed swapped in time for a process"); /* * Swap_idle_threshold2 is the time that a process can be idle before * it will be swapped out, if idle swapping is enabled. */ static int swap_idle_threshold2 = 10; SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold2, CTLFLAG_RW, &swap_idle_threshold2, 0, "Time before a process will be swapped out"); 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); static void swapclear(struct proc *); static int swapout(struct proc *); static void vm_swapout_map_deactivate_pages(vm_map_t, long); static void vm_swapout_object_deactivate_pages(pmap_t, vm_object_t, long); static void swapout_procs(int action); static void vm_req_vmdaemon(int req); static void vm_thread_swapin(struct thread *td); static void vm_thread_swapout(struct thread *td); /* * vm_swapout_object_deactivate_pages * * Deactivate enough pages to satisfy the inactive target * requirements. * * The object and map must be locked. */ static void vm_swapout_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 (should_yield()) goto unlock_return; if (vm_page_busied(p)) continue; VM_CNT_INC(v_pdpages); vm_page_lock(p); if (p->wire_count != 0 || p->hold_count != 0 || !pmap_page_exists_quick(pmap, p)) { vm_page_unlock(p); continue; } act_delta = pmap_ts_referenced(p); if ((p->aflags & PGA_REFERENCED) != 0) { if (act_delta == 0) act_delta = 1; vm_page_aflag_clear(p, PGA_REFERENCED); } if (!vm_page_active(p) && act_delta != 0) { vm_page_activate(p); p->act_count += act_delta; } else if (vm_page_active(p)) { if (act_delta == 0) { p->act_count -= min(p->act_count, ACT_DECLINE); if (!remove_mode && p->act_count == 0) { pmap_remove_all(p); vm_page_deactivate(p); } else vm_page_requeue(p); } else { vm_page_activate(p); if (p->act_count < ACT_MAX - ACT_ADVANCE) p->act_count += ACT_ADVANCE; vm_page_requeue(p); } } else if (vm_page_inactive(p)) pmap_remove_all(p); vm_page_unlock(p); } if ((backing_object = object->backing_object) == NULL) goto unlock_return; VM_OBJECT_RLOCK(backing_object); if (object != first_object) VM_OBJECT_RUNLOCK(object); } unlock_return: if (object != first_object) VM_OBJECT_RUNLOCK(object); } /* * deactivate some number of pages in a map, try to do it fairly, but * that is really hard to do. */ static void vm_swapout_map_deactivate_pages(vm_map_t map, long desired) { vm_map_entry_t tmpe; vm_object_t obj, bigobj; int nothingwired; if (!vm_map_trylock_read(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_swapout_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_swapout_object_deactivate_pages(map->pmap, obj, desired); VM_OBJECT_RUNLOCK(obj); } } tmpe = tmpe->next; } /* * Remove all mappings if a process is swapped out, this will free page * table pages. */ if (desired == 0 && nothingwired) { pmap_remove(vm_map_pmap(map), vm_map_min(map), vm_map_max(map)); } vm_map_unlock_read(map); } /* * Swap out requests */ #define VM_SWAP_NORMAL 1 #define VM_SWAP_IDLE 2 void vm_swapout_run(void) { if (vm_swap_enabled) vm_req_vmdaemon(VM_SWAP_NORMAL); } /* * Idle process swapout -- run once per second when pagedaemons are * reclaiming pages. */ void vm_swapout_run_idle(void) { static long lsec; if (!vm_swap_idle_enabled || time_second == lsec) return; vm_req_vmdaemon(VM_SWAP_IDLE); lsec = time_second; } static void vm_req_vmdaemon(int req) { static int lastrun = 0; mtx_lock(&vm_daemon_mtx); vm_pageout_req_swapout |= req; if ((ticks > (lastrun + hz)) || (ticks < lastrun)) { wakeup(&vm_daemon_needed); lastrun = ticks; } mtx_unlock(&vm_daemon_mtx); } static void vm_daemon(void) { struct rlimit rsslim; struct proc *p; struct thread *td; struct vmspace *vm; int breakout, swapout_flags, tryagain, attempts; #ifdef RACCT uint64_t rsize, ravailable; #endif while (TRUE) { mtx_lock(&vm_daemon_mtx); msleep(&vm_daemon_needed, &vm_daemon_mtx, PPAUSE, "psleep", #ifdef RACCT racct_enable ? hz : 0 #else 0 #endif ); swapout_flags = vm_pageout_req_swapout; vm_pageout_req_swapout = 0; mtx_unlock(&vm_daemon_mtx); if (swapout_flags) swapout_procs(swapout_flags); /* * scan the processes for exceeding their rlimits or if * process is swapped out -- deactivate pages */ tryagain = 0; attempts = 0; again: attempts++; sx_slock(&allproc_lock); FOREACH_PROC_IN_SYSTEM(p) { vm_pindex_t limit, size; /* * if this is a system process or if we have already * looked at this process, skip it. */ PROC_LOCK(p); if (p->p_state != PRS_NORMAL || p->p_flag & (P_INEXEC | P_SYSTEM | P_WEXIT)) { PROC_UNLOCK(p); continue; } /* * if the process is in a non-running type state, * don't touch it. */ breakout = 0; FOREACH_THREAD_IN_PROC(p, td) { thread_lock(td); if (!TD_ON_RUNQ(td) && !TD_IS_RUNNING(td) && !TD_IS_SLEEPING(td) && !TD_IS_SUSPENDED(td)) { thread_unlock(td); breakout = 1; break; } thread_unlock(td); } if (breakout) { PROC_UNLOCK(p); continue; } /* * get a limit */ lim_rlimit_proc(p, RLIMIT_RSS, &rsslim); limit = OFF_TO_IDX( qmin(rsslim.rlim_cur, rsslim.rlim_max)); /* * let processes that are swapped out really be * swapped out set the limit to nothing (will force a * swap-out.) */ if ((p->p_flag & P_INMEM) == 0) limit = 0; /* XXX */ vm = vmspace_acquire_ref(p); _PHOLD_LITE(p); PROC_UNLOCK(p); if (vm == NULL) { PRELE(p); continue; } sx_sunlock(&allproc_lock); size = vmspace_resident_count(vm); if (size >= limit) { vm_swapout_map_deactivate_pages( &vm->vm_map, limit); size = vmspace_resident_count(vm); } #ifdef RACCT if (racct_enable) { rsize = IDX_TO_OFF(size); PROC_LOCK(p); if (p->p_state == PRS_NORMAL) 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_swapout_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); if (p->p_state == PRS_NORMAL) racct_set(p, RACCT_RSS, rsize); PROC_UNLOCK(p); if (rsize > ravailable) tryagain = 1; } } #endif vmspace_free(vm); sx_slock(&allproc_lock); PRELE(p); } sx_sunlock(&allproc_lock); if (tryagain != 0 && attempts <= 10) { maybe_yield(); goto again; } } } /* * Allow a thread's kernel stack to be paged out. */ static void vm_thread_swapout(struct thread *td) { vm_object_t ksobj; vm_page_t m; int i, pages; cpu_thread_swapout(td); pages = td->td_kstack_pages; ksobj = td->td_kstack_obj; pmap_qremove(td->td_kstack, pages); VM_OBJECT_WLOCK(ksobj); for (i = 0; i < pages; i++) { m = vm_page_lookup(ksobj, i); if (m == NULL) panic("vm_thread_swapout: kstack already missing?"); vm_page_dirty(m); vm_page_lock(m); vm_page_unwire(m, PQ_LAUNDRY); vm_page_unlock(m); } VM_OBJECT_WUNLOCK(ksobj); } /* * Bring the kernel stack for a specified thread back in. */ static void vm_thread_swapin(struct thread *td) { vm_object_t ksobj; vm_page_t ma[KSTACK_MAX_PAGES]; int a, count, i, j, pages, rv; pages = td->td_kstack_pages; ksobj = td->td_kstack_obj; VM_OBJECT_WLOCK(ksobj); (void)vm_page_grab_pages(ksobj, 0, VM_ALLOC_NORMAL | VM_ALLOC_WIRED, ma, pages); for (i = 0; i < pages;) { vm_page_assert_xbusied(ma[i]); if (ma[i]->valid == VM_PAGE_BITS_ALL) { vm_page_xunbusy(ma[i]); i++; continue; } vm_object_pip_add(ksobj, 1); for (j = i + 1; j < pages; j++) if (ma[j]->valid == VM_PAGE_BITS_ALL) break; rv = vm_pager_has_page(ksobj, ma[i]->pindex, NULL, &a); KASSERT(rv == 1, ("%s: missing page %p", __func__, ma[i])); count = min(a + 1, j - i); rv = vm_pager_get_pages(ksobj, ma + i, count, NULL, NULL); KASSERT(rv == VM_PAGER_OK, ("%s: cannot get kstack for proc %d", __func__, td->td_proc->p_pid)); vm_object_pip_wakeup(ksobj); for (j = i; j < i + count; j++) vm_page_xunbusy(ma[j]); i += count; } VM_OBJECT_WUNLOCK(ksobj); pmap_qenter(td->td_kstack, ma, pages); cpu_thread_swapin(td); } void faultin(struct proc *p) { struct thread *td; PROC_LOCK_ASSERT(p, MA_OWNED); /* * If another process is swapping in this process, * just wait until it finishes. */ if (p->p_flag & P_SWAPPINGIN) { while (p->p_flag & P_SWAPPINGIN) msleep(&p->p_flag, &p->p_mtx, PVM, "faultin", 0); return; } if ((p->p_flag & P_INMEM) == 0) { /* * Don't let another thread swap process p out while we are * busy swapping it in. */ ++p->p_lock; p->p_flag |= P_SWAPPINGIN; PROC_UNLOCK(p); /* * We hold no lock here because the list of threads * can not change while all threads in the process are * swapped out. */ FOREACH_THREAD_IN_PROC(p, td) vm_thread_swapin(td); PROC_LOCK(p); swapclear(p); p->p_swtick = ticks; wakeup(&p->p_flag); /* Allow other threads to swap p out now. */ --p->p_lock; } } /* * This swapin algorithm attempts to swap-in processes only if there * is enough space for them. Of course, if a process waits for a long * time, it will be swapped in anyway. */ void swapper(void) { struct proc *p, *pp; struct thread *td; int ppri, pri, slptime, swtime; loop: if (vm_page_count_min()) { VM_WAIT; goto loop; } pp = NULL; ppri = INT_MIN; sx_slock(&allproc_lock); FOREACH_PROC_IN_SYSTEM(p) { PROC_LOCK(p); if (p->p_state == PRS_NEW || p->p_flag & (P_SWAPPINGOUT | P_SWAPPINGIN | P_INMEM)) { PROC_UNLOCK(p); continue; } swtime = (ticks - p->p_swtick) / hz; FOREACH_THREAD_IN_PROC(p, td) { /* * An otherwise runnable thread of a process * swapped out has only the TDI_SWAPPED bit set. */ thread_lock(td); if (td->td_inhibitors == TDI_SWAPPED) { slptime = (ticks - td->td_slptick) / hz; pri = swtime + slptime; if ((td->td_flags & TDF_SWAPINREQ) == 0) pri -= p->p_nice * 8; /* * if this thread is higher priority * and there is enough space, then select * this process instead of the previous * selection. */ if (pri > ppri) { pp = p; ppri = pri; } } thread_unlock(td); } PROC_UNLOCK(p); } sx_sunlock(&allproc_lock); /* * Nothing to do, back to sleep. */ if ((p = pp) == NULL) { tsleep(&proc0, PVM, "swapin", MAXSLP * hz / 2); goto loop; } PROC_LOCK(p); /* * Another process may be bringing or may have already * brought this process in while we traverse all threads. * Or, this process may even be being swapped out again. */ if (p->p_flag & (P_INMEM | P_SWAPPINGOUT | P_SWAPPINGIN)) { PROC_UNLOCK(p); goto loop; } /* * We would like to bring someone in. */ faultin(p); PROC_UNLOCK(p); goto loop; } /* * First, if any processes have been sleeping or stopped for at least * "swap_idle_threshold1" seconds, they are swapped out. If, however, * no such processes exist, then the longest-sleeping or stopped * process is swapped out. Finally, and only as a last resort, if * there are no sleeping or stopped processes, the longest-resident * process is swapped out. */ static void swapout_procs(int action) { struct proc *p; struct thread *td; int slptime; bool didswap, doswap; MPASS((action & (VM_SWAP_NORMAL | VM_SWAP_IDLE)) != 0); didswap = false; sx_slock(&allproc_lock); FOREACH_PROC_IN_SYSTEM(p) { /* * Filter out not yet fully constructed processes. Do * not swap out held processes. Avoid processes which * are system, exiting, execing, traced, already swapped * out or are in the process of being swapped in or out. */ PROC_LOCK(p); if (p->p_state != PRS_NORMAL || p->p_lock != 0 || (p->p_flag & (P_SYSTEM | P_WEXIT | P_INEXEC | P_STOPPED_SINGLE | P_TRACED | P_SWAPPINGOUT | P_SWAPPINGIN | P_INMEM)) != P_INMEM) { PROC_UNLOCK(p); continue; } /* * Further consideration of this process for swap out * requires iterating over its threads. We release * allproc_lock here so that process creation and * destruction are not blocked while we iterate. * * To later reacquire allproc_lock and resume * iteration over the allproc list, we will first have * to release the lock on the process. We place a * hold on the process so that it remains in the * allproc list while it is unlocked. */ _PHOLD_LITE(p); sx_sunlock(&allproc_lock); /* * Do not swapout a realtime process. * Guarantee swap_idle_threshold1 time in memory. * If the system is under memory stress, or if we are * swapping idle processes >= swap_idle_threshold2, * then swap the process out. */ doswap = true; FOREACH_THREAD_IN_PROC(p, td) { thread_lock(td); slptime = (ticks - td->td_slptick) / hz; if (PRI_IS_REALTIME(td->td_pri_class) || slptime < swap_idle_threshold1 || !thread_safetoswapout(td) || ((action & VM_SWAP_NORMAL) == 0 && slptime < swap_idle_threshold2)) doswap = false; thread_unlock(td); if (!doswap) break; } if (doswap && swapout(p) == 0) didswap = true; PROC_UNLOCK(p); sx_slock(&allproc_lock); PRELE(p); } sx_sunlock(&allproc_lock); /* * If we swapped something out, and another process needed memory, * then wakeup the sched process. */ if (didswap) wakeup(&proc0); } static void swapclear(struct proc *p) { struct thread *td; PROC_LOCK_ASSERT(p, MA_OWNED); FOREACH_THREAD_IN_PROC(p, td) { thread_lock(td); td->td_flags |= TDF_INMEM; td->td_flags &= ~TDF_SWAPINREQ; TD_CLR_SWAPPED(td); if (TD_CAN_RUN(td)) if (setrunnable(td)) { #ifdef INVARIANTS /* * XXX: We just cleared TDI_SWAPPED * above and set TDF_INMEM, so this * should never happen. */ panic("not waking up swapper"); #endif } thread_unlock(td); } p->p_flag &= ~(P_SWAPPINGIN | P_SWAPPINGOUT); p->p_flag |= P_INMEM; } static int swapout(struct proc *p) { struct thread *td; PROC_LOCK_ASSERT(p, MA_OWNED); /* * The states of this process and its threads may have changed * by now. Assuming that there is only one pageout daemon thread, * this process should still be in memory. */ KASSERT((p->p_flag & (P_INMEM | P_SWAPPINGOUT | P_SWAPPINGIN)) == P_INMEM, ("swapout: lost a swapout race?")); /* * Remember the resident count. */ p->p_vmspace->vm_swrss = vmspace_resident_count(p->p_vmspace); /* * Check and mark all threads before we proceed. */ p->p_flag &= ~P_INMEM; p->p_flag |= P_SWAPPINGOUT; FOREACH_THREAD_IN_PROC(p, td) { thread_lock(td); if (!thread_safetoswapout(td)) { thread_unlock(td); swapclear(p); return (EBUSY); } td->td_flags &= ~TDF_INMEM; TD_SET_SWAPPED(td); thread_unlock(td); } td = FIRST_THREAD_IN_PROC(p); ++td->td_ru.ru_nswap; PROC_UNLOCK(p); /* * This list is stable because all threads are now prevented from * running. The list is only modified in the context of a running * thread in this process. */ FOREACH_THREAD_IN_PROC(p, td) vm_thread_swapout(td); PROC_LOCK(p); p->p_flag &= ~P_SWAPPINGOUT; p->p_swtick = ticks; return (0); }