1 /*- 2 * SPDX-License-Identifier: (BSD-3-Clause AND MIT-CMU) 3 * 4 * Copyright (c) 1991, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * The Mach Operating System project at Carnegie-Mellon University. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 * 34 * from: @(#)vm_page.h 8.2 (Berkeley) 12/13/93 35 * 36 * 37 * Copyright (c) 1987, 1990 Carnegie-Mellon University. 38 * All rights reserved. 39 * 40 * Authors: Avadis Tevanian, Jr., Michael Wayne Young 41 * 42 * Permission to use, copy, modify and distribute this software and 43 * its documentation is hereby granted, provided that both the copyright 44 * notice and this permission notice appear in all copies of the 45 * software, derivative works or modified versions, and any portions 46 * thereof, and that both notices appear in supporting documentation. 47 * 48 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 49 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 50 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 51 * 52 * Carnegie Mellon requests users of this software to return to 53 * 54 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 55 * School of Computer Science 56 * Carnegie Mellon University 57 * Pittsburgh PA 15213-3890 58 * 59 * any improvements or extensions that they make and grant Carnegie the 60 * rights to redistribute these changes. 61 * 62 * $FreeBSD$ 63 */ 64 65 #ifndef _VM_PAGEQUEUE_ 66 #define _VM_PAGEQUEUE_ 67 68 #ifdef _KERNEL 69 struct vm_pagequeue { 70 struct mtx pq_mutex; 71 struct pglist pq_pl; 72 int pq_cnt; 73 const char * const pq_name; 74 uint64_t pq_pdpages; 75 } __aligned(CACHE_LINE_SIZE); 76 77 #if __SIZEOF_LONG__ == 8 78 #define VM_BATCHQUEUE_SIZE 63 79 #else 80 #define VM_BATCHQUEUE_SIZE 15 81 #endif 82 83 struct vm_batchqueue { 84 vm_page_t bq_pa[VM_BATCHQUEUE_SIZE]; 85 int bq_cnt; 86 } __aligned(CACHE_LINE_SIZE); 87 88 #include <vm/uma.h> 89 #include <sys/_blockcount.h> 90 #include <sys/pidctrl.h> 91 struct sysctl_oid; 92 93 /* 94 * One vm_domain per NUMA domain. Contains pagequeues, free page structures, 95 * and accounting. 96 * 97 * Lock Key: 98 * f vmd_free_mtx 99 * p vmd_pageout_mtx 100 * d vm_domainset_lock 101 * a atomic 102 * c const after boot 103 * q page queue lock 104 * 105 * A unique page daemon thread manages each vm_domain structure and is 106 * responsible for ensuring that some free memory is available by freeing 107 * inactive pages and aging active pages. To decide how many pages to process, 108 * it uses thresholds derived from the number of pages in the domain: 109 * 110 * vmd_page_count 111 * --- 112 * | 113 * |-> vmd_inactive_target (~3%) 114 * | - The active queue scan target is given by 115 * | (vmd_inactive_target + vmd_free_target - vmd_free_count). 116 * | 117 * | 118 * |-> vmd_free_target (~2%) 119 * | - Target for page reclamation. 120 * | 121 * |-> vmd_pageout_wakeup_thresh (~1.8%) 122 * | - Threshold for waking up the page daemon. 123 * | 124 * | 125 * |-> vmd_free_min (~0.5%) 126 * | - First low memory threshold. 127 * | - Causes per-CPU caching to be lazily disabled in UMA. 128 * | - vm_wait() sleeps below this threshold. 129 * | 130 * |-> vmd_free_severe (~0.25%) 131 * | - Second low memory threshold. 132 * | - Triggers aggressive UMA reclamation, disables delayed buffer 133 * | writes. 134 * | 135 * |-> vmd_free_reserved (~0.13%) 136 * | - Minimum for VM_ALLOC_NORMAL page allocations. 137 * |-> vmd_pageout_free_min (32 + 2 pages) 138 * | - Minimum for waking a page daemon thread sleeping in vm_wait(). 139 * |-> vmd_interrupt_free_min (2 pages) 140 * | - Minimum for VM_ALLOC_SYSTEM page allocations. 141 * --- 142 * 143 *-- 144 * Free page count regulation: 145 * 146 * The page daemon attempts to ensure that the free page count is above the free 147 * target. It wakes up periodically (every 100ms) to input the current free 148 * page shortage (free_target - free_count) to a PID controller, which in 149 * response outputs the number of pages to attempt to reclaim. The shortage's 150 * current magnitude, rate of change, and cumulative value are together used to 151 * determine the controller's output. The page daemon target thus adapts 152 * dynamically to the system's demand for free pages, resulting in less 153 * burstiness than a simple hysteresis loop. 154 * 155 * When the free page count drops below the wakeup threshold, 156 * vm_domain_allocate() proactively wakes up the page daemon. This helps ensure 157 * that the system responds promptly to a large instantaneous free page 158 * shortage. 159 * 160 * The page daemon also attempts to ensure that some fraction of the system's 161 * memory is present in the inactive (I) and laundry (L) page queues, so that it 162 * can respond promptly to a sudden free page shortage. In particular, the page 163 * daemon thread aggressively scans active pages so long as the following 164 * condition holds: 165 * 166 * len(I) + len(L) + free_target - free_count < inactive_target 167 * 168 * Otherwise, when the inactive target is met, the page daemon periodically 169 * scans a small portion of the active queue in order to maintain up-to-date 170 * per-page access history. Unreferenced pages in the active queue thus 171 * eventually migrate to the inactive queue. 172 * 173 * The per-domain laundry thread periodically launders dirty pages based on the 174 * number of clean pages freed by the page daemon since the last laundering. If 175 * the page daemon fails to meet its scan target (i.e., the PID controller 176 * output) because of a shortage of clean inactive pages, the laundry thread 177 * attempts to launder enough pages to meet the free page target. 178 * 179 *-- 180 * Page allocation priorities: 181 * 182 * The system defines three page allocation priorities: VM_ALLOC_NORMAL, 183 * VM_ALLOC_SYSTEM and VM_ALLOC_INTERRUPT. An interrupt-priority allocation can 184 * claim any free page. This priority is used in the pmap layer when attempting 185 * to allocate a page for the kernel page tables; in such cases an allocation 186 * failure will usually result in a kernel panic. The system priority is used 187 * for most other kernel memory allocations, for instance by UMA's slab 188 * allocator or the buffer cache. Such allocations will fail if the free count 189 * is below interrupt_free_min. All other allocations occur at the normal 190 * priority, which is typically used for allocation of user pages, for instance 191 * in the page fault handler or when allocating page table pages or pv_entry 192 * structures for user pmaps. Such allocations fail if the free count is below 193 * the free_reserved threshold. 194 * 195 *-- 196 * Free memory shortages: 197 * 198 * The system uses the free_min and free_severe thresholds to apply 199 * back-pressure and give the page daemon a chance to recover. When a page 200 * allocation fails due to a shortage and the allocating thread cannot handle 201 * failure, it may call vm_wait() to sleep until free pages are available. 202 * vm_domain_freecnt_inc() wakes sleeping threads once the free page count rises 203 * above the free_min threshold; the page daemon and laundry threads are given 204 * priority and will wake up once free_count reaches the (much smaller) 205 * pageout_free_min threshold. 206 * 207 * On NUMA systems, the domainset iterators always prefer NUMA domains where the 208 * free page count is above the free_min threshold. This means that given the 209 * choice between two NUMA domains, one above the free_min threshold and one 210 * below, the former will be used to satisfy the allocation request regardless 211 * of the domain selection policy. 212 * 213 * In addition to reclaiming memory from the page queues, the vm_lowmem event 214 * fires every ten seconds so long as the system is under memory pressure (i.e., 215 * vmd_free_count < vmd_free_target). This allows kernel subsystems to register 216 * for notifications of free page shortages, upon which they may shrink their 217 * caches. Following a vm_lowmem event, UMA's caches are pruned to ensure that 218 * they do not contain an excess of unused memory. When a domain is below the 219 * free_min threshold, UMA limits the population of per-CPU caches. When a 220 * domain falls below the free_severe threshold, UMA's caches are completely 221 * drained. 222 * 223 * If the system encounters a global memory shortage, it may resort to the 224 * out-of-memory (OOM) killer, which selects a process and delivers SIGKILL in a 225 * last-ditch attempt to free up some pages. Either of the two following 226 * conditions will activate the OOM killer: 227 * 228 * 1. The page daemons collectively fail to reclaim any pages during their 229 * inactive queue scans. After vm_pageout_oom_seq consecutive scans fail, 230 * the page daemon thread votes for an OOM kill, and an OOM kill is 231 * triggered when all page daemons have voted. This heuristic is strict and 232 * may fail to trigger even when the system is effectively deadlocked. 233 * 234 * 2. Threads in the user fault handler are repeatedly unable to make progress 235 * while allocating a page to satisfy the fault. After 236 * vm_pfault_oom_attempts page allocation failures with intervening 237 * vm_wait() calls, the faulting thread will trigger an OOM kill. 238 */ 239 struct vm_domain { 240 struct vm_pagequeue vmd_pagequeues[PQ_COUNT]; 241 struct mtx_padalign vmd_free_mtx; 242 struct mtx_padalign vmd_pageout_mtx; 243 struct vm_pgcache { 244 int domain; 245 int pool; 246 uma_zone_t zone; 247 } vmd_pgcache[VM_NFREEPOOL]; 248 struct vmem *vmd_kernel_arena; /* (c) per-domain kva R/W arena. */ 249 struct vmem *vmd_kernel_rwx_arena; /* (c) per-domain kva R/W/X arena. */ 250 u_int vmd_domain; /* (c) Domain number. */ 251 u_int vmd_page_count; /* (c) Total page count. */ 252 long vmd_segs; /* (c) bitmask of the segments */ 253 u_int __aligned(CACHE_LINE_SIZE) vmd_free_count; /* (a,f) free page count */ 254 u_int vmd_pageout_deficit; /* (a) Estimated number of pages deficit */ 255 uint8_t vmd_pad[CACHE_LINE_SIZE - (sizeof(u_int) * 2)]; 256 257 /* Paging control variables, used within single threaded page daemon. */ 258 struct pidctrl vmd_pid; /* Pageout controller. */ 259 boolean_t vmd_oom; 260 u_int vmd_inactive_threads; 261 u_int vmd_inactive_shortage; /* Per-thread shortage. */ 262 blockcount_t vmd_inactive_running; /* Number of inactive threads. */ 263 blockcount_t vmd_inactive_starting; /* Number of threads started. */ 264 volatile u_int vmd_addl_shortage; /* Shortage accumulator. */ 265 volatile u_int vmd_inactive_freed; /* Successful inactive frees. */ 266 volatile u_int vmd_inactive_us; /* Microseconds for above. */ 267 u_int vmd_inactive_pps; /* Exponential decay frees/second. */ 268 int vmd_oom_seq; 269 int vmd_last_active_scan; 270 struct vm_page vmd_markers[PQ_COUNT]; /* (q) markers for queue scans */ 271 struct vm_page vmd_inacthead; /* marker for LRU-defeating insertions */ 272 struct vm_page vmd_clock[2]; /* markers for active queue scan */ 273 274 int vmd_pageout_wanted; /* (a, p) pageout daemon wait channel */ 275 int vmd_pageout_pages_needed; /* (d) page daemon waiting for pages? */ 276 bool vmd_minset; /* (d) Are we in vm_min_domains? */ 277 bool vmd_severeset; /* (d) Are we in vm_severe_domains? */ 278 enum { 279 VM_LAUNDRY_IDLE = 0, 280 VM_LAUNDRY_BACKGROUND, 281 VM_LAUNDRY_SHORTFALL 282 } vmd_laundry_request; 283 284 /* Paging thresholds and targets. */ 285 u_int vmd_clean_pages_freed; /* (q) accumulator for laundry thread */ 286 u_int vmd_background_launder_target; /* (c) */ 287 u_int vmd_free_reserved; /* (c) pages reserved for deadlock */ 288 u_int vmd_free_target; /* (c) pages desired free */ 289 u_int vmd_free_min; /* (c) pages desired free */ 290 u_int vmd_inactive_target; /* (c) pages desired inactive */ 291 u_int vmd_pageout_free_min; /* (c) min pages reserved for kernel */ 292 u_int vmd_pageout_wakeup_thresh;/* (c) min pages to wake pagedaemon */ 293 u_int vmd_interrupt_free_min; /* (c) reserved pages for int code */ 294 u_int vmd_free_severe; /* (c) severe page depletion point */ 295 296 /* Name for sysctl etc. */ 297 struct sysctl_oid *vmd_oid; 298 char vmd_name[sizeof(__XSTRING(MAXMEMDOM))]; 299 } __aligned(CACHE_LINE_SIZE); 300 301 extern struct vm_domain vm_dom[MAXMEMDOM]; 302 303 #define VM_DOMAIN(n) (&vm_dom[(n)]) 304 #define VM_DOMAIN_EMPTY(n) (vm_dom[(n)].vmd_page_count == 0) 305 306 #define vm_pagequeue_assert_locked(pq) mtx_assert(&(pq)->pq_mutex, MA_OWNED) 307 #define vm_pagequeue_lock(pq) mtx_lock(&(pq)->pq_mutex) 308 #define vm_pagequeue_lockptr(pq) (&(pq)->pq_mutex) 309 #define vm_pagequeue_trylock(pq) mtx_trylock(&(pq)->pq_mutex) 310 #define vm_pagequeue_unlock(pq) mtx_unlock(&(pq)->pq_mutex) 311 312 #define vm_domain_free_assert_locked(n) \ 313 mtx_assert(vm_domain_free_lockptr((n)), MA_OWNED) 314 #define vm_domain_free_assert_unlocked(n) \ 315 mtx_assert(vm_domain_free_lockptr((n)), MA_NOTOWNED) 316 #define vm_domain_free_lock(d) \ 317 mtx_lock(vm_domain_free_lockptr((d))) 318 #define vm_domain_free_lockptr(d) \ 319 (&(d)->vmd_free_mtx) 320 #define vm_domain_free_trylock(d) \ 321 mtx_trylock(vm_domain_free_lockptr((d))) 322 #define vm_domain_free_unlock(d) \ 323 mtx_unlock(vm_domain_free_lockptr((d))) 324 325 #define vm_domain_pageout_lockptr(d) \ 326 (&(d)->vmd_pageout_mtx) 327 #define vm_domain_pageout_assert_locked(n) \ 328 mtx_assert(vm_domain_pageout_lockptr((n)), MA_OWNED) 329 #define vm_domain_pageout_assert_unlocked(n) \ 330 mtx_assert(vm_domain_pageout_lockptr((n)), MA_NOTOWNED) 331 #define vm_domain_pageout_lock(d) \ 332 mtx_lock(vm_domain_pageout_lockptr((d))) 333 #define vm_domain_pageout_unlock(d) \ 334 mtx_unlock(vm_domain_pageout_lockptr((d))) 335 336 static __inline void 337 vm_pagequeue_cnt_add(struct vm_pagequeue *pq, int addend) 338 { 339 340 vm_pagequeue_assert_locked(pq); 341 pq->pq_cnt += addend; 342 } 343 #define vm_pagequeue_cnt_inc(pq) vm_pagequeue_cnt_add((pq), 1) 344 #define vm_pagequeue_cnt_dec(pq) vm_pagequeue_cnt_add((pq), -1) 345 346 static inline void 347 vm_pagequeue_remove(struct vm_pagequeue *pq, vm_page_t m) 348 { 349 350 TAILQ_REMOVE(&pq->pq_pl, m, plinks.q); 351 vm_pagequeue_cnt_dec(pq); 352 } 353 354 static inline void 355 vm_batchqueue_init(struct vm_batchqueue *bq) 356 { 357 358 bq->bq_cnt = 0; 359 } 360 361 static inline int 362 vm_batchqueue_insert(struct vm_batchqueue *bq, vm_page_t m) 363 { 364 int slots_free; 365 366 slots_free = nitems(bq->bq_pa) - bq->bq_cnt; 367 if (slots_free > 0) { 368 bq->bq_pa[bq->bq_cnt++] = m; 369 return (slots_free); 370 } 371 return (slots_free); 372 } 373 374 static inline vm_page_t 375 vm_batchqueue_pop(struct vm_batchqueue *bq) 376 { 377 378 if (bq->bq_cnt == 0) 379 return (NULL); 380 return (bq->bq_pa[--bq->bq_cnt]); 381 } 382 383 void vm_domain_set(struct vm_domain *vmd); 384 void vm_domain_clear(struct vm_domain *vmd); 385 int vm_domain_allocate(struct vm_domain *vmd, int req, int npages); 386 387 /* 388 * vm_pagequeue_domain: 389 * 390 * Return the memory domain the page belongs to. 391 */ 392 static inline struct vm_domain * 393 vm_pagequeue_domain(vm_page_t m) 394 { 395 396 return (VM_DOMAIN(vm_page_domain(m))); 397 } 398 399 /* 400 * Return the number of pages we need to free-up or cache 401 * A positive number indicates that we do not have enough free pages. 402 */ 403 static inline int 404 vm_paging_target(struct vm_domain *vmd) 405 { 406 407 return (vmd->vmd_free_target - vmd->vmd_free_count); 408 } 409 410 /* 411 * Returns TRUE if the pagedaemon needs to be woken up. 412 */ 413 static inline int 414 vm_paging_needed(struct vm_domain *vmd, u_int free_count) 415 { 416 417 return (free_count < vmd->vmd_pageout_wakeup_thresh); 418 } 419 420 /* 421 * Returns TRUE if the domain is below the min paging target. 422 */ 423 static inline int 424 vm_paging_min(struct vm_domain *vmd) 425 { 426 427 return (vmd->vmd_free_min > vmd->vmd_free_count); 428 } 429 430 /* 431 * Returns TRUE if the domain is below the severe paging target. 432 */ 433 static inline int 434 vm_paging_severe(struct vm_domain *vmd) 435 { 436 437 return (vmd->vmd_free_severe > vmd->vmd_free_count); 438 } 439 440 /* 441 * Return the number of pages we need to launder. 442 * A positive number indicates that we have a shortfall of clean pages. 443 */ 444 static inline int 445 vm_laundry_target(struct vm_domain *vmd) 446 { 447 448 return (vm_paging_target(vmd)); 449 } 450 451 void pagedaemon_wakeup(int domain); 452 453 static inline void 454 vm_domain_freecnt_inc(struct vm_domain *vmd, int adj) 455 { 456 u_int old, new; 457 458 old = atomic_fetchadd_int(&vmd->vmd_free_count, adj); 459 new = old + adj; 460 /* 461 * Only update bitsets on transitions. Notice we short-circuit the 462 * rest of the checks if we're above min already. 463 */ 464 if (old < vmd->vmd_free_min && (new >= vmd->vmd_free_min || 465 (old < vmd->vmd_free_severe && new >= vmd->vmd_free_severe) || 466 (old < vmd->vmd_pageout_free_min && 467 new >= vmd->vmd_pageout_free_min))) 468 vm_domain_clear(vmd); 469 } 470 471 #endif /* _KERNEL */ 472 #endif /* !_VM_PAGEQUEUE_ */ 473