/*- * SPDX-License-Identifier: (BSD-3-Clause AND MIT-CMU) * * Copyright (c) 1991, 1993 * The Regents of the University of California. All rights reserved. * * This code is derived from software contributed to Berkeley by * The Mach Operating System project at Carnegie-Mellon University. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. 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. * * * 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. */ #ifndef _VM_PAGEQUEUE_ #define _VM_PAGEQUEUE_ #ifdef _KERNEL struct vm_pagequeue { struct mtx pq_mutex; struct pglist pq_pl; int pq_cnt; const char * const pq_name; uint64_t pq_pdpages; } __aligned(CACHE_LINE_SIZE); #if __SIZEOF_LONG__ == 8 #define VM_BATCHQUEUE_SIZE 63 #else #define VM_BATCHQUEUE_SIZE 15 #endif struct vm_batchqueue { vm_page_t bq_pa[VM_BATCHQUEUE_SIZE]; int bq_cnt; } __aligned(CACHE_LINE_SIZE); #include <vm/uma.h> #include <sys/_blockcount.h> #include <sys/pidctrl.h> struct sysctl_oid; /* * One vm_domain per NUMA domain. Contains pagequeues, free page structures, * and accounting. * * Lock Key: * f vmd_free_mtx * p vmd_pageout_mtx * d vm_domainset_lock * a atomic * c const after boot * q page queue lock * * A unique page daemon thread manages each vm_domain structure and is * responsible for ensuring that some free memory is available by freeing * inactive pages and aging active pages. To decide how many pages to process, * it uses thresholds derived from the number of pages in the domain: * * vmd_page_count * --- * | * |-> vmd_inactive_target (~3%) * | - The active queue scan target is given by * | (vmd_inactive_target + vmd_free_target - vmd_free_count). * | * | * |-> vmd_free_target (~2%) * | - Target for page reclamation. * | * |-> vmd_pageout_wakeup_thresh (~1.8%) * | - Threshold for waking up the page daemon. * | * | * |-> vmd_free_min (~0.5%) * | - First low memory threshold. * | - Causes per-CPU caching to be lazily disabled in UMA. * | - vm_wait() sleeps below this threshold. * | * |-> vmd_free_severe (~0.25%) * | - Second low memory threshold. * | - Triggers aggressive UMA reclamation, disables delayed buffer * | writes. * | * |-> vmd_free_reserved (~0.13%) * | - Minimum for VM_ALLOC_NORMAL page allocations. * |-> vmd_pageout_free_min (32 + 2 pages) * | - Minimum for waking a page daemon thread sleeping in vm_wait(). * |-> vmd_interrupt_free_min (2 pages) * | - Minimum for VM_ALLOC_SYSTEM page allocations. * --- * *-- * Free page count regulation: * * The page daemon attempts to ensure that the free page count is above the free * target. It wakes up periodically (every 100ms) to input the current free * page shortage (free_target - free_count) to a PID controller, which in * response outputs the number of pages to attempt to reclaim. The shortage's * current magnitude, rate of change, and cumulative value are together used to * determine the controller's output. The page daemon target thus adapts * dynamically to the system's demand for free pages, resulting in less * burstiness than a simple hysteresis loop. * * When the free page count drops below the wakeup threshold, * vm_domain_allocate() proactively wakes up the page daemon. This helps ensure * that the system responds promptly to a large instantaneous free page * shortage. * * The page daemon also attempts to ensure that some fraction of the system's * memory is present in the inactive (I) and laundry (L) page queues, so that it * can respond promptly to a sudden free page shortage. In particular, the page * daemon thread aggressively scans active pages so long as the following * condition holds: * * len(I) + len(L) + free_target - free_count < inactive_target * * Otherwise, when the inactive target is met, the page daemon periodically * scans a small portion of the active queue in order to maintain up-to-date * per-page access history. Unreferenced pages in the active queue thus * eventually migrate to the inactive queue. * * The per-domain laundry thread periodically launders dirty pages based on the * number of clean pages freed by the page daemon since the last laundering. If * the page daemon fails to meet its scan target (i.e., the PID controller * output) because of a shortage of clean inactive pages, the laundry thread * attempts to launder enough pages to meet the free page target. * *-- * Page allocation priorities: * * The system defines three page allocation priorities: VM_ALLOC_NORMAL, * VM_ALLOC_SYSTEM and VM_ALLOC_INTERRUPT. An interrupt-priority allocation can * claim any free page. This priority is used in the pmap layer when attempting * to allocate a page for the kernel page tables; in such cases an allocation * failure will usually result in a kernel panic. The system priority is used * for most other kernel memory allocations, for instance by UMA's slab * allocator or the buffer cache. Such allocations will fail if the free count * is below interrupt_free_min. All other allocations occur at the normal * priority, which is typically used for allocation of user pages, for instance * in the page fault handler or when allocating page table pages or pv_entry * structures for user pmaps. Such allocations fail if the free count is below * the free_reserved threshold. * *-- * Free memory shortages: * * The system uses the free_min and free_severe thresholds to apply * back-pressure and give the page daemon a chance to recover. When a page * allocation fails due to a shortage and the allocating thread cannot handle * failure, it may call vm_wait() to sleep until free pages are available. * vm_domain_freecnt_inc() wakes sleeping threads once the free page count rises * above the free_min threshold; the page daemon and laundry threads are given * priority and will wake up once free_count reaches the (much smaller) * pageout_free_min threshold. * * On NUMA systems, the domainset iterators always prefer NUMA domains where the * free page count is above the free_min threshold. This means that given the * choice between two NUMA domains, one above the free_min threshold and one * below, the former will be used to satisfy the allocation request regardless * of the domain selection policy. * * In addition to reclaiming memory from the page queues, the vm_lowmem event * fires every ten seconds so long as the system is under memory pressure (i.e., * vmd_free_count < vmd_free_target). This allows kernel subsystems to register * for notifications of free page shortages, upon which they may shrink their * caches. Following a vm_lowmem event, UMA's caches are pruned to ensure that * they do not contain an excess of unused memory. When a domain is below the * free_min threshold, UMA limits the population of per-CPU caches. When a * domain falls below the free_severe threshold, UMA's caches are completely * drained. * * If the system encounters a global memory shortage, it may resort to the * out-of-memory (OOM) killer, which selects a process and delivers SIGKILL in a * last-ditch attempt to free up some pages. Either of the two following * conditions will activate the OOM killer: * * 1. The page daemons collectively fail to reclaim any pages during their * inactive queue scans. After vm_pageout_oom_seq consecutive scans fail, * the page daemon thread votes for an OOM kill, and an OOM kill is * triggered when all page daemons have voted. This heuristic is strict and * may fail to trigger even when the system is effectively deadlocked. * * 2. Threads in the user fault handler are repeatedly unable to make progress * while allocating a page to satisfy the fault. After * vm_pfault_oom_attempts page allocation failures with intervening * vm_wait() calls, the faulting thread will trigger an OOM kill. */ struct vm_domain { struct vm_pagequeue vmd_pagequeues[PQ_COUNT]; struct mtx_padalign vmd_free_mtx; struct mtx_padalign vmd_pageout_mtx; struct vm_pgcache { int domain; int pool; uma_zone_t zone; } vmd_pgcache[VM_NFREEPOOL]; struct vmem *vmd_kernel_arena; /* (c) per-domain kva R/W arena. */ struct vmem *vmd_kernel_rwx_arena; /* (c) per-domain kva R/W/X arena. */ struct vmem *vmd_kernel_nofree_arena; /* (c) per-domain kva NOFREE arena. */ u_int vmd_domain; /* (c) Domain number. */ u_int vmd_page_count; /* (c) Total page count. */ long vmd_segs; /* (c) bitmask of the segments */ struct pglist vmd_nofreeq; /* (f) NOFREE page bump allocator. */ u_int __aligned(CACHE_LINE_SIZE) vmd_free_count; /* (a,f) free page count */ u_int vmd_pageout_deficit; /* (a) Estimated number of pages deficit */ uint8_t vmd_pad[CACHE_LINE_SIZE - (sizeof(u_int) * 2)]; /* Paging control variables, used within single threaded page daemon. */ struct pidctrl vmd_pid; /* Pageout controller. */ bool vmd_oom; /* An OOM kill was requested. */ bool vmd_helper_threads_enabled;/* Use multiple threads to scan. */ u_int vmd_inactive_threads; /* Number of extra helper threads. */ u_int vmd_inactive_shortage; /* Per-thread shortage. */ blockcount_t vmd_inactive_running; /* Number of inactive threads. */ blockcount_t vmd_inactive_starting; /* Number of threads started. */ u_int vmd_addl_shortage; /* (a) Shortage accumulator. */ u_int vmd_inactive_freed; /* (a) Successful inactive frees. */ u_int vmd_inactive_us; /* (a) Microseconds for above. */ u_int vmd_inactive_pps; /* Exponential decay frees/second. */ int vmd_oom_seq; int vmd_last_active_scan; struct vm_page vmd_markers[PQ_COUNT]; /* (q) markers for queue scans */ struct vm_page vmd_inacthead; /* marker for LRU-defeating insertions */ struct vm_page vmd_clock[2]; /* markers for active queue scan */ int vmd_pageout_wanted; /* (a, p) pageout daemon wait channel */ int vmd_pageout_pages_needed; /* (d) page daemon waiting for pages? */ bool vmd_minset; /* (d) Are we in vm_min_domains? */ bool vmd_severeset; /* (d) Are we in vm_severe_domains? */ enum { VM_LAUNDRY_IDLE = 0, VM_LAUNDRY_BACKGROUND, VM_LAUNDRY_SHORTFALL } vmd_laundry_request; /* Paging thresholds and targets. */ u_int vmd_clean_pages_freed; /* (q) accumulator for laundry thread */ u_int vmd_background_launder_target; /* (c) */ u_int vmd_free_reserved; /* (c) pages reserved for deadlock */ u_int vmd_free_target; /* (c) pages desired free */ u_int vmd_free_min; /* (c) pages desired free */ u_int vmd_inactive_target; /* (c) pages desired inactive */ u_int vmd_pageout_free_min; /* (c) min pages reserved for kernel */ u_int vmd_pageout_wakeup_thresh;/* (c) min pages to wake pagedaemon */ u_int vmd_interrupt_free_min; /* (c) reserved pages for int code */ u_int vmd_free_severe; /* (c) severe page depletion point */ /* Name for sysctl etc. */ struct sysctl_oid *vmd_oid; char vmd_name[sizeof(__XSTRING(MAXMEMDOM))]; } __aligned(CACHE_LINE_SIZE); extern struct vm_domain vm_dom[MAXMEMDOM]; #define VM_DOMAIN(n) (&vm_dom[(n)]) #define VM_DOMAIN_EMPTY(n) (vm_dom[(n)].vmd_page_count == 0) #define vm_pagequeue_assert_locked(pq) mtx_assert(&(pq)->pq_mutex, MA_OWNED) #define vm_pagequeue_lock(pq) mtx_lock(&(pq)->pq_mutex) #define vm_pagequeue_lockptr(pq) (&(pq)->pq_mutex) #define vm_pagequeue_trylock(pq) mtx_trylock(&(pq)->pq_mutex) #define vm_pagequeue_unlock(pq) mtx_unlock(&(pq)->pq_mutex) #define vm_domain_free_assert_locked(n) \ mtx_assert(vm_domain_free_lockptr((n)), MA_OWNED) #define vm_domain_free_assert_unlocked(n) \ mtx_assert(vm_domain_free_lockptr((n)), MA_NOTOWNED) #define vm_domain_free_lock(d) \ mtx_lock(vm_domain_free_lockptr((d))) #define vm_domain_free_lockptr(d) \ (&(d)->vmd_free_mtx) #define vm_domain_free_trylock(d) \ mtx_trylock(vm_domain_free_lockptr((d))) #define vm_domain_free_unlock(d) \ mtx_unlock(vm_domain_free_lockptr((d))) #define vm_domain_pageout_lockptr(d) \ (&(d)->vmd_pageout_mtx) #define vm_domain_pageout_assert_locked(n) \ mtx_assert(vm_domain_pageout_lockptr((n)), MA_OWNED) #define vm_domain_pageout_assert_unlocked(n) \ mtx_assert(vm_domain_pageout_lockptr((n)), MA_NOTOWNED) #define vm_domain_pageout_lock(d) \ mtx_lock(vm_domain_pageout_lockptr((d))) #define vm_domain_pageout_unlock(d) \ mtx_unlock(vm_domain_pageout_lockptr((d))) static __inline void vm_pagequeue_cnt_add(struct vm_pagequeue *pq, int addend) { vm_pagequeue_assert_locked(pq); pq->pq_cnt += addend; } #define vm_pagequeue_cnt_inc(pq) vm_pagequeue_cnt_add((pq), 1) #define vm_pagequeue_cnt_dec(pq) vm_pagequeue_cnt_add((pq), -1) static inline void vm_pagequeue_remove(struct vm_pagequeue *pq, vm_page_t m) { TAILQ_REMOVE(&pq->pq_pl, m, plinks.q); vm_pagequeue_cnt_dec(pq); } static inline void vm_batchqueue_init(struct vm_batchqueue *bq) { bq->bq_cnt = 0; } static inline bool vm_batchqueue_empty(const struct vm_batchqueue *bq) { return (bq->bq_cnt == 0); } static inline int vm_batchqueue_insert(struct vm_batchqueue *bq, vm_page_t m) { int slots_free; slots_free = nitems(bq->bq_pa) - bq->bq_cnt; if (slots_free > 0) { bq->bq_pa[bq->bq_cnt++] = m; return (slots_free); } return (slots_free); } static inline vm_page_t vm_batchqueue_pop(struct vm_batchqueue *bq) { if (bq->bq_cnt == 0) return (NULL); return (bq->bq_pa[--bq->bq_cnt]); } void vm_domain_set(struct vm_domain *vmd); void vm_domain_clear(struct vm_domain *vmd); int vm_domain_allocate(struct vm_domain *vmd, int req, int npages); /* * vm_pagequeue_domain: * * Return the memory domain the page belongs to. */ static inline struct vm_domain * vm_pagequeue_domain(vm_page_t m) { return (VM_DOMAIN(vm_page_domain(m))); } /* * Return the number of pages we need to free-up or cache * A positive number indicates that we do not have enough free pages. */ static inline int vm_paging_target(struct vm_domain *vmd) { return (vmd->vmd_free_target - vmd->vmd_free_count); } /* * Returns TRUE if the pagedaemon needs to be woken up. */ static inline int vm_paging_needed(struct vm_domain *vmd, u_int free_count) { return (free_count < vmd->vmd_pageout_wakeup_thresh); } /* * Returns TRUE if the domain is below the min paging target. */ static inline int vm_paging_min(struct vm_domain *vmd) { return (vmd->vmd_free_min > vmd->vmd_free_count); } /* * Returns TRUE if the domain is below the severe paging target. */ static inline int vm_paging_severe(struct vm_domain *vmd) { return (vmd->vmd_free_severe > vmd->vmd_free_count); } /* * Return the number of pages we need to launder. * A positive number indicates that we have a shortfall of clean pages. */ static inline int vm_laundry_target(struct vm_domain *vmd) { return (vm_paging_target(vmd)); } void pagedaemon_wakeup(int domain); static inline void vm_domain_freecnt_inc(struct vm_domain *vmd, int adj) { u_int old, new; old = atomic_fetchadd_int(&vmd->vmd_free_count, adj); new = old + adj; /* * Only update bitsets on transitions. Notice we short-circuit the * rest of the checks if we're above min already. */ if (old < vmd->vmd_free_min && (new >= vmd->vmd_free_min || (old < vmd->vmd_free_severe && new >= vmd->vmd_free_severe) || (old < vmd->vmd_pageout_free_min && new >= vmd->vmd_pageout_free_min))) vm_domain_clear(vmd); } #endif /* _KERNEL */ #endif /* !_VM_PAGEQUEUE_ */
