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 #ifndef VM_BATCHQUEUE_SIZE 78 #define VM_BATCHQUEUE_SIZE 7 79 #endif 80 81 struct vm_batchqueue { 82 vm_page_t bq_pa[VM_BATCHQUEUE_SIZE]; 83 int bq_cnt; 84 } __aligned(CACHE_LINE_SIZE); 85 86 #include <vm/uma.h> 87 #include <sys/_blockcount.h> 88 #include <sys/pidctrl.h> 89 struct sysctl_oid; 90 91 /* 92 * One vm_domain per NUMA domain. Contains pagequeues, free page structures, 93 * and accounting. 94 * 95 * Lock Key: 96 * f vmd_free_mtx 97 * p vmd_pageout_mtx 98 * d vm_domainset_lock 99 * a atomic 100 * c const after boot 101 * q page queue lock 102 * 103 * A unique page daemon thread manages each vm_domain structure and is 104 * responsible for ensuring that some free memory is available by freeing 105 * inactive pages and aging active pages. To decide how many pages to process, 106 * it uses thresholds derived from the number of pages in the domain: 107 * 108 * vmd_page_count 109 * --- 110 * | 111 * |-> vmd_inactive_target (~3%) 112 * | - The active queue scan target is given by 113 * | (vmd_inactive_target + vmd_free_target - vmd_free_count). 114 * | 115 * | 116 * |-> vmd_free_target (~2%) 117 * | - Target for page reclamation. 118 * | 119 * |-> vmd_pageout_wakeup_thresh (~1.8%) 120 * | - Threshold for waking up the page daemon. 121 * | 122 * | 123 * |-> vmd_free_min (~0.5%) 124 * | - First low memory threshold. 125 * | - Causes per-CPU caching to be lazily disabled in UMA. 126 * | - vm_wait() sleeps below this threshold. 127 * | 128 * |-> vmd_free_severe (~0.25%) 129 * | - Second low memory threshold. 130 * | - Triggers aggressive UMA reclamation, disables delayed buffer 131 * | writes. 132 * | 133 * |-> vmd_free_reserved (~0.13%) 134 * | - Minimum for VM_ALLOC_NORMAL page allocations. 135 * |-> vmd_pageout_free_min (32 + 2 pages) 136 * | - Minimum for waking a page daemon thread sleeping in vm_wait(). 137 * |-> vmd_interrupt_free_min (2 pages) 138 * | - Minimum for VM_ALLOC_SYSTEM page allocations. 139 * --- 140 * 141 *-- 142 * Free page count regulation: 143 * 144 * The page daemon attempts to ensure that the free page count is above the free 145 * target. It wakes up periodically (every 100ms) to input the current free 146 * page shortage (free_target - free_count) to a PID controller, which in 147 * response outputs the number of pages to attempt to reclaim. The shortage's 148 * current magnitude, rate of change, and cumulative value are together used to 149 * determine the controller's output. The page daemon target thus adapts 150 * dynamically to the system's demand for free pages, resulting in less 151 * burstiness than a simple hysteresis loop. 152 * 153 * When the free page count drops below the wakeup threshold, 154 * vm_domain_allocate() proactively wakes up the page daemon. This helps ensure 155 * that the system responds promptly to a large instantaneous free page 156 * shortage. 157 * 158 * The page daemon also attempts to ensure that some fraction of the system's 159 * memory is present in the inactive (I) and laundry (L) page queues, so that it 160 * can respond promptly to a sudden free page shortage. In particular, the page 161 * daemon thread aggressively scans active pages so long as the following 162 * condition holds: 163 * 164 * len(I) + len(L) + free_target - free_count < inactive_target 165 * 166 * Otherwise, when the inactive target is met, the page daemon periodically 167 * scans a small portion of the active queue in order to maintain up-to-date 168 * per-page access history. Unreferenced pages in the active queue thus 169 * eventually migrate to the inactive queue. 170 * 171 * The per-domain laundry thread periodically launders dirty pages based on the 172 * number of clean pages freed by the page daemon since the last laundering. If 173 * the page daemon fails to meet its scan target (i.e., the PID controller 174 * output) because of a shortage of clean inactive pages, the laundry thread 175 * attempts to launder enough pages to meet the free page target. 176 * 177 *-- 178 * Page allocation priorities: 179 * 180 * The system defines three page allocation priorities: VM_ALLOC_NORMAL, 181 * VM_ALLOC_SYSTEM and VM_ALLOC_INTERRUPT. An interrupt-priority allocation can 182 * claim any free page. This priority is used in the pmap layer when attempting 183 * to allocate a page for the kernel page tables; in such cases an allocation 184 * failure will usually result in a kernel panic. The system priority is used 185 * for most other kernel memory allocations, for instance by UMA's slab 186 * allocator or the buffer cache. Such allocations will fail if the free count 187 * is below interrupt_free_min. All other allocations occur at the normal 188 * priority, which is typically used for allocation of user pages, for instance 189 * in the page fault handler or when allocating page table pages or pv_entry 190 * structures for user pmaps. Such allocations fail if the free count is below 191 * the free_reserved threshold. 192 * 193 *-- 194 * Free memory shortages: 195 * 196 * The system uses the free_min and free_severe thresholds to apply 197 * back-pressure and give the page daemon a chance to recover. When a page 198 * allocation fails due to a shortage and the allocating thread cannot handle 199 * failure, it may call vm_wait() to sleep until free pages are available. 200 * vm_domain_freecnt_inc() wakes sleeping threads once the free page count rises 201 * above the free_min threshold; the page daemon and laundry threads are given 202 * priority and will wake up once free_count reaches the (much smaller) 203 * pageout_free_min threshold. 204 * 205 * On NUMA systems, the domainset iterators always prefer NUMA domains where the 206 * free page count is above the free_min threshold. This means that given the 207 * choice between two NUMA domains, one above the free_min threshold and one 208 * below, the former will be used to satisfy the allocation request regardless 209 * of the domain selection policy. 210 * 211 * In addition to reclaiming memory from the page queues, the vm_lowmem event 212 * fires every ten seconds so long as the system is under memory pressure (i.e., 213 * vmd_free_count < vmd_free_target). This allows kernel subsystems to register 214 * for notifications of free page shortages, upon which they may shrink their 215 * caches. Following a vm_lowmem event, UMA's caches are pruned to ensure that 216 * they do not contain an excess of unused memory. When a domain is below the 217 * free_min threshold, UMA limits the population of per-CPU caches. When a 218 * domain falls below the free_severe threshold, UMA's caches are completely 219 * drained. 220 * 221 * If the system encounters a global memory shortage, it may resort to the 222 * out-of-memory (OOM) killer, which selects a process and delivers SIGKILL in a 223 * last-ditch attempt to free up some pages. Either of the two following 224 * conditions will activate the OOM killer: 225 * 226 * 1. The page daemons collectively fail to reclaim any pages during their 227 * inactive queue scans. After vm_pageout_oom_seq consecutive scans fail, 228 * the page daemon thread votes for an OOM kill, and an OOM kill is 229 * triggered when all page daemons have voted. This heuristic is strict and 230 * may fail to trigger even when the system is effectively deadlocked. 231 * 232 * 2. Threads in the user fault handler are repeatedly unable to make progress 233 * while allocating a page to satisfy the fault. After 234 * vm_pfault_oom_attempts page allocation failures with intervening 235 * vm_wait() calls, the faulting thread will trigger an OOM kill. 236 */ 237 struct vm_domain { 238 struct vm_pagequeue vmd_pagequeues[PQ_COUNT]; 239 struct mtx_padalign vmd_free_mtx; 240 struct mtx_padalign vmd_pageout_mtx; 241 struct vm_pgcache { 242 int domain; 243 int pool; 244 uma_zone_t zone; 245 } vmd_pgcache[VM_NFREEPOOL]; 246 struct vmem *vmd_kernel_arena; /* (c) per-domain kva R/W arena. */ 247 struct vmem *vmd_kernel_rwx_arena; /* (c) per-domain kva R/W/X arena. */ 248 u_int vmd_domain; /* (c) Domain number. */ 249 u_int vmd_page_count; /* (c) Total page count. */ 250 long vmd_segs; /* (c) bitmask of the segments */ 251 u_int __aligned(CACHE_LINE_SIZE) vmd_free_count; /* (a,f) free page count */ 252 u_int vmd_pageout_deficit; /* (a) Estimated number of pages deficit */ 253 uint8_t vmd_pad[CACHE_LINE_SIZE - (sizeof(u_int) * 2)]; 254 255 /* Paging control variables, used within single threaded page daemon. */ 256 struct pidctrl vmd_pid; /* Pageout controller. */ 257 boolean_t vmd_oom; 258 u_int vmd_inactive_threads; 259 u_int vmd_inactive_shortage; /* Per-thread shortage. */ 260 blockcount_t vmd_inactive_running; /* Number of inactive threads. */ 261 blockcount_t vmd_inactive_starting; /* Number of threads started. */ 262 volatile u_int vmd_addl_shortage; /* Shortage accumulator. */ 263 volatile u_int vmd_inactive_freed; /* Successful inactive frees. */ 264 volatile u_int vmd_inactive_us; /* Microseconds for above. */ 265 u_int vmd_inactive_pps; /* Exponential decay frees/second. */ 266 int vmd_oom_seq; 267 int vmd_last_active_scan; 268 struct vm_page vmd_markers[PQ_COUNT]; /* (q) markers for queue scans */ 269 struct vm_page vmd_inacthead; /* marker for LRU-defeating insertions */ 270 struct vm_page vmd_clock[2]; /* markers for active queue scan */ 271 272 int vmd_pageout_wanted; /* (a, p) pageout daemon wait channel */ 273 int vmd_pageout_pages_needed; /* (d) page daemon waiting for pages? */ 274 bool vmd_minset; /* (d) Are we in vm_min_domains? */ 275 bool vmd_severeset; /* (d) Are we in vm_severe_domains? */ 276 enum { 277 VM_LAUNDRY_IDLE = 0, 278 VM_LAUNDRY_BACKGROUND, 279 VM_LAUNDRY_SHORTFALL 280 } vmd_laundry_request; 281 282 /* Paging thresholds and targets. */ 283 u_int vmd_clean_pages_freed; /* (q) accumulator for laundry thread */ 284 u_int vmd_background_launder_target; /* (c) */ 285 u_int vmd_free_reserved; /* (c) pages reserved for deadlock */ 286 u_int vmd_free_target; /* (c) pages desired free */ 287 u_int vmd_free_min; /* (c) pages desired free */ 288 u_int vmd_inactive_target; /* (c) pages desired inactive */ 289 u_int vmd_pageout_free_min; /* (c) min pages reserved for kernel */ 290 u_int vmd_pageout_wakeup_thresh;/* (c) min pages to wake pagedaemon */ 291 u_int vmd_interrupt_free_min; /* (c) reserved pages for int code */ 292 u_int vmd_free_severe; /* (c) severe page depletion point */ 293 294 /* Name for sysctl etc. */ 295 struct sysctl_oid *vmd_oid; 296 char vmd_name[sizeof(__XSTRING(MAXMEMDOM))]; 297 } __aligned(CACHE_LINE_SIZE); 298 299 extern struct vm_domain vm_dom[MAXMEMDOM]; 300 301 #define VM_DOMAIN(n) (&vm_dom[(n)]) 302 #define VM_DOMAIN_EMPTY(n) (vm_dom[(n)].vmd_page_count == 0) 303 304 #define vm_pagequeue_assert_locked(pq) mtx_assert(&(pq)->pq_mutex, MA_OWNED) 305 #define vm_pagequeue_lock(pq) mtx_lock(&(pq)->pq_mutex) 306 #define vm_pagequeue_lockptr(pq) (&(pq)->pq_mutex) 307 #define vm_pagequeue_trylock(pq) mtx_trylock(&(pq)->pq_mutex) 308 #define vm_pagequeue_unlock(pq) mtx_unlock(&(pq)->pq_mutex) 309 310 #define vm_domain_free_assert_locked(n) \ 311 mtx_assert(vm_domain_free_lockptr((n)), MA_OWNED) 312 #define vm_domain_free_assert_unlocked(n) \ 313 mtx_assert(vm_domain_free_lockptr((n)), MA_NOTOWNED) 314 #define vm_domain_free_lock(d) \ 315 mtx_lock(vm_domain_free_lockptr((d))) 316 #define vm_domain_free_lockptr(d) \ 317 (&(d)->vmd_free_mtx) 318 #define vm_domain_free_trylock(d) \ 319 mtx_trylock(vm_domain_free_lockptr((d))) 320 #define vm_domain_free_unlock(d) \ 321 mtx_unlock(vm_domain_free_lockptr((d))) 322 323 #define vm_domain_pageout_lockptr(d) \ 324 (&(d)->vmd_pageout_mtx) 325 #define vm_domain_pageout_assert_locked(n) \ 326 mtx_assert(vm_domain_pageout_lockptr((n)), MA_OWNED) 327 #define vm_domain_pageout_assert_unlocked(n) \ 328 mtx_assert(vm_domain_pageout_lockptr((n)), MA_NOTOWNED) 329 #define vm_domain_pageout_lock(d) \ 330 mtx_lock(vm_domain_pageout_lockptr((d))) 331 #define vm_domain_pageout_unlock(d) \ 332 mtx_unlock(vm_domain_pageout_lockptr((d))) 333 334 static __inline void 335 vm_pagequeue_cnt_add(struct vm_pagequeue *pq, int addend) 336 { 337 338 vm_pagequeue_assert_locked(pq); 339 pq->pq_cnt += addend; 340 } 341 #define vm_pagequeue_cnt_inc(pq) vm_pagequeue_cnt_add((pq), 1) 342 #define vm_pagequeue_cnt_dec(pq) vm_pagequeue_cnt_add((pq), -1) 343 344 static inline void 345 vm_pagequeue_remove(struct vm_pagequeue *pq, vm_page_t m) 346 { 347 348 TAILQ_REMOVE(&pq->pq_pl, m, plinks.q); 349 vm_pagequeue_cnt_dec(pq); 350 } 351 352 static inline void 353 vm_batchqueue_init(struct vm_batchqueue *bq) 354 { 355 356 bq->bq_cnt = 0; 357 } 358 359 static inline bool 360 vm_batchqueue_insert(struct vm_batchqueue *bq, vm_page_t m) 361 { 362 363 if (bq->bq_cnt < nitems(bq->bq_pa)) { 364 bq->bq_pa[bq->bq_cnt++] = m; 365 return (true); 366 } 367 return (false); 368 } 369 370 static inline vm_page_t 371 vm_batchqueue_pop(struct vm_batchqueue *bq) 372 { 373 374 if (bq->bq_cnt == 0) 375 return (NULL); 376 return (bq->bq_pa[--bq->bq_cnt]); 377 } 378 379 void vm_domain_set(struct vm_domain *vmd); 380 void vm_domain_clear(struct vm_domain *vmd); 381 int vm_domain_allocate(struct vm_domain *vmd, int req, int npages); 382 383 /* 384 * vm_pagequeue_domain: 385 * 386 * Return the memory domain the page belongs to. 387 */ 388 static inline struct vm_domain * 389 vm_pagequeue_domain(vm_page_t m) 390 { 391 392 return (VM_DOMAIN(vm_page_domain(m))); 393 } 394 395 /* 396 * Return the number of pages we need to free-up or cache 397 * A positive number indicates that we do not have enough free pages. 398 */ 399 static inline int 400 vm_paging_target(struct vm_domain *vmd) 401 { 402 403 return (vmd->vmd_free_target - vmd->vmd_free_count); 404 } 405 406 /* 407 * Returns TRUE if the pagedaemon needs to be woken up. 408 */ 409 static inline int 410 vm_paging_needed(struct vm_domain *vmd, u_int free_count) 411 { 412 413 return (free_count < vmd->vmd_pageout_wakeup_thresh); 414 } 415 416 /* 417 * Returns TRUE if the domain is below the min paging target. 418 */ 419 static inline int 420 vm_paging_min(struct vm_domain *vmd) 421 { 422 423 return (vmd->vmd_free_min > vmd->vmd_free_count); 424 } 425 426 /* 427 * Returns TRUE if the domain is below the severe paging target. 428 */ 429 static inline int 430 vm_paging_severe(struct vm_domain *vmd) 431 { 432 433 return (vmd->vmd_free_severe > vmd->vmd_free_count); 434 } 435 436 /* 437 * Return the number of pages we need to launder. 438 * A positive number indicates that we have a shortfall of clean pages. 439 */ 440 static inline int 441 vm_laundry_target(struct vm_domain *vmd) 442 { 443 444 return (vm_paging_target(vmd)); 445 } 446 447 void pagedaemon_wakeup(int domain); 448 449 static inline void 450 vm_domain_freecnt_inc(struct vm_domain *vmd, int adj) 451 { 452 u_int old, new; 453 454 old = atomic_fetchadd_int(&vmd->vmd_free_count, adj); 455 new = old + adj; 456 /* 457 * Only update bitsets on transitions. Notice we short-circuit the 458 * rest of the checks if we're above min already. 459 */ 460 if (old < vmd->vmd_free_min && (new >= vmd->vmd_free_min || 461 (old < vmd->vmd_free_severe && new >= vmd->vmd_free_severe) || 462 (old < vmd->vmd_pageout_free_min && 463 new >= vmd->vmd_pageout_free_min))) 464 vm_domain_clear(vmd); 465 } 466 467 #endif /* _KERNEL */ 468 #endif /* !_VM_PAGEQUEUE_ */ 469