1 /*- 2 * Copyright (c) 1991 Regents of the University of California. 3 * All rights reserved. 4 * Copyright (c) 1994 John S. Dyson 5 * All rights reserved. 6 * Copyright (c) 1994 David Greenman 7 * All rights reserved. 8 * Copyright (c) 2005 Yahoo! Technologies Norway AS 9 * All rights reserved. 10 * 11 * This code is derived from software contributed to Berkeley by 12 * The Mach Operating System project at Carnegie-Mellon University. 13 * 14 * Redistribution and use in source and binary forms, with or without 15 * modification, are permitted provided that the following conditions 16 * are met: 17 * 1. Redistributions of source code must retain the above copyright 18 * notice, this list of conditions and the following disclaimer. 19 * 2. Redistributions in binary form must reproduce the above copyright 20 * notice, this list of conditions and the following disclaimer in the 21 * documentation and/or other materials provided with the distribution. 22 * 3. All advertising materials mentioning features or use of this software 23 * must display the following acknowledgement: 24 * This product includes software developed by the University of 25 * California, Berkeley and its contributors. 26 * 4. Neither the name of the University nor the names of its contributors 27 * may be used to endorse or promote products derived from this software 28 * without specific prior written permission. 29 * 30 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 31 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 32 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 33 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 34 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 35 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 36 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 37 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 38 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 39 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 40 * SUCH DAMAGE. 41 * 42 * from: @(#)vm_pageout.c 7.4 (Berkeley) 5/7/91 43 * 44 * 45 * Copyright (c) 1987, 1990 Carnegie-Mellon University. 46 * All rights reserved. 47 * 48 * Authors: Avadis Tevanian, Jr., Michael Wayne Young 49 * 50 * Permission to use, copy, modify and distribute this software and 51 * its documentation is hereby granted, provided that both the copyright 52 * notice and this permission notice appear in all copies of the 53 * software, derivative works or modified versions, and any portions 54 * thereof, and that both notices appear in supporting documentation. 55 * 56 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 57 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 58 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 59 * 60 * Carnegie Mellon requests users of this software to return to 61 * 62 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 63 * School of Computer Science 64 * Carnegie Mellon University 65 * Pittsburgh PA 15213-3890 66 * 67 * any improvements or extensions that they make and grant Carnegie the 68 * rights to redistribute these changes. 69 */ 70 71 #include <sys/cdefs.h> 72 __FBSDID("$FreeBSD$"); 73 74 #include "opt_kstack_pages.h" 75 #include "opt_kstack_max_pages.h" 76 #include "opt_vm.h" 77 78 #include <sys/param.h> 79 #include <sys/systm.h> 80 #include <sys/limits.h> 81 #include <sys/kernel.h> 82 #include <sys/eventhandler.h> 83 #include <sys/lock.h> 84 #include <sys/mutex.h> 85 #include <sys/proc.h> 86 #include <sys/_kstack_cache.h> 87 #include <sys/kthread.h> 88 #include <sys/ktr.h> 89 #include <sys/mount.h> 90 #include <sys/racct.h> 91 #include <sys/resourcevar.h> 92 #include <sys/sched.h> 93 #include <sys/sdt.h> 94 #include <sys/signalvar.h> 95 #include <sys/smp.h> 96 #include <sys/time.h> 97 #include <sys/vnode.h> 98 #include <sys/vmmeter.h> 99 #include <sys/rwlock.h> 100 #include <sys/sx.h> 101 #include <sys/sysctl.h> 102 103 #include <vm/vm.h> 104 #include <vm/vm_param.h> 105 #include <vm/vm_object.h> 106 #include <vm/vm_page.h> 107 #include <vm/vm_map.h> 108 #include <vm/vm_pageout.h> 109 #include <vm/vm_pager.h> 110 #include <vm/vm_phys.h> 111 #include <vm/swap_pager.h> 112 #include <vm/vm_extern.h> 113 #include <vm/uma.h> 114 115 /* the kernel process "vm_daemon" */ 116 static void vm_daemon(void); 117 static struct proc *vmproc; 118 119 static struct kproc_desc vm_kp = { 120 "vmdaemon", 121 vm_daemon, 122 &vmproc 123 }; 124 SYSINIT(vmdaemon, SI_SUB_KTHREAD_VM, SI_ORDER_FIRST, kproc_start, &vm_kp); 125 126 static int vm_swap_enabled = 1; 127 static int vm_swap_idle_enabled = 0; 128 129 SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled, CTLFLAG_RW, 130 &vm_swap_enabled, 0, 131 "Enable entire process swapout"); 132 SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled, CTLFLAG_RW, 133 &vm_swap_idle_enabled, 0, 134 "Allow swapout on idle criteria"); 135 136 /* 137 * Swap_idle_threshold1 is the guaranteed swapped in time for a process 138 */ 139 static int swap_idle_threshold1 = 2; 140 SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold1, CTLFLAG_RW, 141 &swap_idle_threshold1, 0, 142 "Guaranteed swapped in time for a process"); 143 144 /* 145 * Swap_idle_threshold2 is the time that a process can be idle before 146 * it will be swapped out, if idle swapping is enabled. 147 */ 148 static int swap_idle_threshold2 = 10; 149 SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold2, CTLFLAG_RW, 150 &swap_idle_threshold2, 0, 151 "Time before a process will be swapped out"); 152 153 static int vm_pageout_req_swapout; /* XXX */ 154 static int vm_daemon_needed; 155 static struct mtx vm_daemon_mtx; 156 /* Allow for use by vm_pageout before vm_daemon is initialized. */ 157 MTX_SYSINIT(vm_daemon, &vm_daemon_mtx, "vm daemon", MTX_DEF); 158 159 static void swapclear(struct proc *); 160 static int swapout(struct proc *); 161 static void vm_swapout_map_deactivate_pages(vm_map_t, long); 162 static void vm_swapout_object_deactivate_pages(pmap_t, vm_object_t, long); 163 static void swapout_procs(int action); 164 static void vm_req_vmdaemon(int req); 165 static void vm_thread_swapin(struct thread *td); 166 static void vm_thread_swapout(struct thread *td); 167 168 /* 169 * vm_swapout_object_deactivate_pages 170 * 171 * Deactivate enough pages to satisfy the inactive target 172 * requirements. 173 * 174 * The object and map must be locked. 175 */ 176 static void 177 vm_swapout_object_deactivate_pages(pmap_t pmap, vm_object_t first_object, 178 long desired) 179 { 180 vm_object_t backing_object, object; 181 vm_page_t p; 182 int act_delta, remove_mode; 183 184 VM_OBJECT_ASSERT_LOCKED(first_object); 185 if ((first_object->flags & OBJ_FICTITIOUS) != 0) 186 return; 187 for (object = first_object;; object = backing_object) { 188 if (pmap_resident_count(pmap) <= desired) 189 goto unlock_return; 190 VM_OBJECT_ASSERT_LOCKED(object); 191 if ((object->flags & OBJ_UNMANAGED) != 0 || 192 object->paging_in_progress != 0) 193 goto unlock_return; 194 195 remove_mode = 0; 196 if (object->shadow_count > 1) 197 remove_mode = 1; 198 /* 199 * Scan the object's entire memory queue. 200 */ 201 TAILQ_FOREACH(p, &object->memq, listq) { 202 if (pmap_resident_count(pmap) <= desired) 203 goto unlock_return; 204 if (vm_page_busied(p)) 205 continue; 206 VM_CNT_INC(v_pdpages); 207 vm_page_lock(p); 208 if (p->wire_count != 0 || p->hold_count != 0 || 209 !pmap_page_exists_quick(pmap, p)) { 210 vm_page_unlock(p); 211 continue; 212 } 213 act_delta = pmap_ts_referenced(p); 214 if ((p->aflags & PGA_REFERENCED) != 0) { 215 if (act_delta == 0) 216 act_delta = 1; 217 vm_page_aflag_clear(p, PGA_REFERENCED); 218 } 219 if (!vm_page_active(p) && act_delta != 0) { 220 vm_page_activate(p); 221 p->act_count += act_delta; 222 } else if (vm_page_active(p)) { 223 if (act_delta == 0) { 224 p->act_count -= min(p->act_count, 225 ACT_DECLINE); 226 if (!remove_mode && p->act_count == 0) { 227 pmap_remove_all(p); 228 vm_page_deactivate(p); 229 } else 230 vm_page_requeue(p); 231 } else { 232 vm_page_activate(p); 233 if (p->act_count < ACT_MAX - 234 ACT_ADVANCE) 235 p->act_count += ACT_ADVANCE; 236 vm_page_requeue(p); 237 } 238 } else if (vm_page_inactive(p)) 239 pmap_remove_all(p); 240 vm_page_unlock(p); 241 } 242 if ((backing_object = object->backing_object) == NULL) 243 goto unlock_return; 244 VM_OBJECT_RLOCK(backing_object); 245 if (object != first_object) 246 VM_OBJECT_RUNLOCK(object); 247 } 248 unlock_return: 249 if (object != first_object) 250 VM_OBJECT_RUNLOCK(object); 251 } 252 253 /* 254 * deactivate some number of pages in a map, try to do it fairly, but 255 * that is really hard to do. 256 */ 257 static void 258 vm_swapout_map_deactivate_pages(vm_map_t map, long desired) 259 { 260 vm_map_entry_t tmpe; 261 vm_object_t obj, bigobj; 262 int nothingwired; 263 264 if (!vm_map_trylock(map)) 265 return; 266 267 bigobj = NULL; 268 nothingwired = TRUE; 269 270 /* 271 * first, search out the biggest object, and try to free pages from 272 * that. 273 */ 274 tmpe = map->header.next; 275 while (tmpe != &map->header) { 276 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) { 277 obj = tmpe->object.vm_object; 278 if (obj != NULL && VM_OBJECT_TRYRLOCK(obj)) { 279 if (obj->shadow_count <= 1 && 280 (bigobj == NULL || 281 bigobj->resident_page_count < 282 obj->resident_page_count)) { 283 if (bigobj != NULL) 284 VM_OBJECT_RUNLOCK(bigobj); 285 bigobj = obj; 286 } else 287 VM_OBJECT_RUNLOCK(obj); 288 } 289 } 290 if (tmpe->wired_count > 0) 291 nothingwired = FALSE; 292 tmpe = tmpe->next; 293 } 294 295 if (bigobj != NULL) { 296 vm_swapout_object_deactivate_pages(map->pmap, bigobj, desired); 297 VM_OBJECT_RUNLOCK(bigobj); 298 } 299 /* 300 * Next, hunt around for other pages to deactivate. We actually 301 * do this search sort of wrong -- .text first is not the best idea. 302 */ 303 tmpe = map->header.next; 304 while (tmpe != &map->header) { 305 if (pmap_resident_count(vm_map_pmap(map)) <= desired) 306 break; 307 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) { 308 obj = tmpe->object.vm_object; 309 if (obj != NULL) { 310 VM_OBJECT_RLOCK(obj); 311 vm_swapout_object_deactivate_pages(map->pmap, 312 obj, desired); 313 VM_OBJECT_RUNLOCK(obj); 314 } 315 } 316 tmpe = tmpe->next; 317 } 318 319 /* 320 * Remove all mappings if a process is swapped out, this will free page 321 * table pages. 322 */ 323 if (desired == 0 && nothingwired) { 324 pmap_remove(vm_map_pmap(map), vm_map_min(map), 325 vm_map_max(map)); 326 } 327 328 vm_map_unlock(map); 329 } 330 331 /* 332 * Swap out requests 333 */ 334 #define VM_SWAP_NORMAL 1 335 #define VM_SWAP_IDLE 2 336 337 void 338 vm_swapout_run(void) 339 { 340 341 if (vm_swap_enabled) 342 vm_req_vmdaemon(VM_SWAP_NORMAL); 343 } 344 345 /* 346 * Idle process swapout -- run once per second when pagedaemons are 347 * reclaiming pages. 348 */ 349 void 350 vm_swapout_run_idle(void) 351 { 352 static long lsec; 353 354 if (!vm_swap_idle_enabled || time_second == lsec) 355 return; 356 vm_req_vmdaemon(VM_SWAP_IDLE); 357 lsec = time_second; 358 } 359 360 static void 361 vm_req_vmdaemon(int req) 362 { 363 static int lastrun = 0; 364 365 mtx_lock(&vm_daemon_mtx); 366 vm_pageout_req_swapout |= req; 367 if ((ticks > (lastrun + hz)) || (ticks < lastrun)) { 368 wakeup(&vm_daemon_needed); 369 lastrun = ticks; 370 } 371 mtx_unlock(&vm_daemon_mtx); 372 } 373 374 static void 375 vm_daemon(void) 376 { 377 struct rlimit rsslim; 378 struct proc *p; 379 struct thread *td; 380 struct vmspace *vm; 381 int breakout, swapout_flags, tryagain, attempts; 382 #ifdef RACCT 383 uint64_t rsize, ravailable; 384 #endif 385 386 while (TRUE) { 387 mtx_lock(&vm_daemon_mtx); 388 msleep(&vm_daemon_needed, &vm_daemon_mtx, PPAUSE, "psleep", 389 #ifdef RACCT 390 racct_enable ? hz : 0 391 #else 392 0 393 #endif 394 ); 395 swapout_flags = vm_pageout_req_swapout; 396 vm_pageout_req_swapout = 0; 397 mtx_unlock(&vm_daemon_mtx); 398 if (swapout_flags) 399 swapout_procs(swapout_flags); 400 401 /* 402 * scan the processes for exceeding their rlimits or if 403 * process is swapped out -- deactivate pages 404 */ 405 tryagain = 0; 406 attempts = 0; 407 again: 408 attempts++; 409 sx_slock(&allproc_lock); 410 FOREACH_PROC_IN_SYSTEM(p) { 411 vm_pindex_t limit, size; 412 413 /* 414 * if this is a system process or if we have already 415 * looked at this process, skip it. 416 */ 417 PROC_LOCK(p); 418 if (p->p_state != PRS_NORMAL || 419 p->p_flag & (P_INEXEC | P_SYSTEM | P_WEXIT)) { 420 PROC_UNLOCK(p); 421 continue; 422 } 423 /* 424 * if the process is in a non-running type state, 425 * don't touch it. 426 */ 427 breakout = 0; 428 FOREACH_THREAD_IN_PROC(p, td) { 429 thread_lock(td); 430 if (!TD_ON_RUNQ(td) && 431 !TD_IS_RUNNING(td) && 432 !TD_IS_SLEEPING(td) && 433 !TD_IS_SUSPENDED(td)) { 434 thread_unlock(td); 435 breakout = 1; 436 break; 437 } 438 thread_unlock(td); 439 } 440 if (breakout) { 441 PROC_UNLOCK(p); 442 continue; 443 } 444 /* 445 * get a limit 446 */ 447 lim_rlimit_proc(p, RLIMIT_RSS, &rsslim); 448 limit = OFF_TO_IDX( 449 qmin(rsslim.rlim_cur, rsslim.rlim_max)); 450 451 /* 452 * let processes that are swapped out really be 453 * swapped out set the limit to nothing (will force a 454 * swap-out.) 455 */ 456 if ((p->p_flag & P_INMEM) == 0) 457 limit = 0; /* XXX */ 458 vm = vmspace_acquire_ref(p); 459 _PHOLD_LITE(p); 460 PROC_UNLOCK(p); 461 if (vm == NULL) { 462 PRELE(p); 463 continue; 464 } 465 sx_sunlock(&allproc_lock); 466 467 size = vmspace_resident_count(vm); 468 if (size >= limit) { 469 vm_swapout_map_deactivate_pages( 470 &vm->vm_map, limit); 471 size = vmspace_resident_count(vm); 472 } 473 #ifdef RACCT 474 if (racct_enable) { 475 rsize = IDX_TO_OFF(size); 476 PROC_LOCK(p); 477 if (p->p_state == PRS_NORMAL) 478 racct_set(p, RACCT_RSS, rsize); 479 ravailable = racct_get_available(p, RACCT_RSS); 480 PROC_UNLOCK(p); 481 if (rsize > ravailable) { 482 /* 483 * Don't be overly aggressive; this 484 * might be an innocent process, 485 * and the limit could've been exceeded 486 * by some memory hog. Don't try 487 * to deactivate more than 1/4th 488 * of process' resident set size. 489 */ 490 if (attempts <= 8) { 491 if (ravailable < rsize - 492 (rsize / 4)) { 493 ravailable = rsize - 494 (rsize / 4); 495 } 496 } 497 vm_swapout_map_deactivate_pages( 498 &vm->vm_map, 499 OFF_TO_IDX(ravailable)); 500 /* Update RSS usage after paging out. */ 501 size = vmspace_resident_count(vm); 502 rsize = IDX_TO_OFF(size); 503 PROC_LOCK(p); 504 if (p->p_state == PRS_NORMAL) 505 racct_set(p, RACCT_RSS, rsize); 506 PROC_UNLOCK(p); 507 if (rsize > ravailable) 508 tryagain = 1; 509 } 510 } 511 #endif 512 vmspace_free(vm); 513 sx_slock(&allproc_lock); 514 PRELE(p); 515 } 516 sx_sunlock(&allproc_lock); 517 if (tryagain != 0 && attempts <= 10) 518 goto again; 519 } 520 } 521 522 /* 523 * Allow a thread's kernel stack to be paged out. 524 */ 525 static void 526 vm_thread_swapout(struct thread *td) 527 { 528 vm_object_t ksobj; 529 vm_page_t m; 530 int i, pages; 531 532 cpu_thread_swapout(td); 533 pages = td->td_kstack_pages; 534 ksobj = td->td_kstack_obj; 535 pmap_qremove(td->td_kstack, pages); 536 VM_OBJECT_WLOCK(ksobj); 537 for (i = 0; i < pages; i++) { 538 m = vm_page_lookup(ksobj, i); 539 if (m == NULL) 540 panic("vm_thread_swapout: kstack already missing?"); 541 vm_page_dirty(m); 542 vm_page_lock(m); 543 vm_page_unwire(m, PQ_INACTIVE); 544 vm_page_unlock(m); 545 } 546 VM_OBJECT_WUNLOCK(ksobj); 547 } 548 549 /* 550 * Bring the kernel stack for a specified thread back in. 551 */ 552 static void 553 vm_thread_swapin(struct thread *td) 554 { 555 vm_object_t ksobj; 556 vm_page_t ma[KSTACK_MAX_PAGES]; 557 int pages; 558 559 pages = td->td_kstack_pages; 560 ksobj = td->td_kstack_obj; 561 VM_OBJECT_WLOCK(ksobj); 562 (void)vm_page_grab_pages(ksobj, 0, VM_ALLOC_NORMAL | VM_ALLOC_WIRED, ma, 563 pages); 564 for (int i = 0; i < pages;) { 565 int j, a, count, rv; 566 567 vm_page_assert_xbusied(ma[i]); 568 if (ma[i]->valid == VM_PAGE_BITS_ALL) { 569 vm_page_xunbusy(ma[i]); 570 i++; 571 continue; 572 } 573 vm_object_pip_add(ksobj, 1); 574 for (j = i + 1; j < pages; j++) 575 if (ma[j]->valid == VM_PAGE_BITS_ALL) 576 break; 577 rv = vm_pager_has_page(ksobj, ma[i]->pindex, NULL, &a); 578 KASSERT(rv == 1, ("%s: missing page %p", __func__, ma[i])); 579 count = min(a + 1, j - i); 580 rv = vm_pager_get_pages(ksobj, ma + i, count, NULL, NULL); 581 KASSERT(rv == VM_PAGER_OK, ("%s: cannot get kstack for proc %d", 582 __func__, td->td_proc->p_pid)); 583 vm_object_pip_wakeup(ksobj); 584 for (j = i; j < i + count; j++) 585 vm_page_xunbusy(ma[j]); 586 i += count; 587 } 588 VM_OBJECT_WUNLOCK(ksobj); 589 pmap_qenter(td->td_kstack, ma, pages); 590 cpu_thread_swapin(td); 591 } 592 593 void 594 faultin(struct proc *p) 595 { 596 struct thread *td; 597 598 PROC_LOCK_ASSERT(p, MA_OWNED); 599 /* 600 * If another process is swapping in this process, 601 * just wait until it finishes. 602 */ 603 if (p->p_flag & P_SWAPPINGIN) { 604 while (p->p_flag & P_SWAPPINGIN) 605 msleep(&p->p_flag, &p->p_mtx, PVM, "faultin", 0); 606 return; 607 } 608 if ((p->p_flag & P_INMEM) == 0) { 609 /* 610 * Don't let another thread swap process p out while we are 611 * busy swapping it in. 612 */ 613 ++p->p_lock; 614 p->p_flag |= P_SWAPPINGIN; 615 PROC_UNLOCK(p); 616 617 /* 618 * We hold no lock here because the list of threads 619 * can not change while all threads in the process are 620 * swapped out. 621 */ 622 FOREACH_THREAD_IN_PROC(p, td) 623 vm_thread_swapin(td); 624 PROC_LOCK(p); 625 swapclear(p); 626 p->p_swtick = ticks; 627 628 wakeup(&p->p_flag); 629 630 /* Allow other threads to swap p out now. */ 631 --p->p_lock; 632 } 633 } 634 635 /* 636 * This swapin algorithm attempts to swap-in processes only if there 637 * is enough space for them. Of course, if a process waits for a long 638 * time, it will be swapped in anyway. 639 */ 640 void 641 swapper(void) 642 { 643 struct proc *p; 644 struct thread *td; 645 struct proc *pp; 646 int slptime; 647 int swtime; 648 int ppri; 649 int pri; 650 651 loop: 652 if (vm_page_count_min()) { 653 VM_WAIT; 654 goto loop; 655 } 656 657 pp = NULL; 658 ppri = INT_MIN; 659 sx_slock(&allproc_lock); 660 FOREACH_PROC_IN_SYSTEM(p) { 661 PROC_LOCK(p); 662 if (p->p_state == PRS_NEW || 663 p->p_flag & (P_SWAPPINGOUT | P_SWAPPINGIN | P_INMEM)) { 664 PROC_UNLOCK(p); 665 continue; 666 } 667 swtime = (ticks - p->p_swtick) / hz; 668 FOREACH_THREAD_IN_PROC(p, td) { 669 /* 670 * An otherwise runnable thread of a process 671 * swapped out has only the TDI_SWAPPED bit set. 672 */ 673 thread_lock(td); 674 if (td->td_inhibitors == TDI_SWAPPED) { 675 slptime = (ticks - td->td_slptick) / hz; 676 pri = swtime + slptime; 677 if ((td->td_flags & TDF_SWAPINREQ) == 0) 678 pri -= p->p_nice * 8; 679 /* 680 * if this thread is higher priority 681 * and there is enough space, then select 682 * this process instead of the previous 683 * selection. 684 */ 685 if (pri > ppri) { 686 pp = p; 687 ppri = pri; 688 } 689 } 690 thread_unlock(td); 691 } 692 PROC_UNLOCK(p); 693 } 694 sx_sunlock(&allproc_lock); 695 696 /* 697 * Nothing to do, back to sleep. 698 */ 699 if ((p = pp) == NULL) { 700 tsleep(&proc0, PVM, "swapin", MAXSLP * hz / 2); 701 goto loop; 702 } 703 PROC_LOCK(p); 704 705 /* 706 * Another process may be bringing or may have already 707 * brought this process in while we traverse all threads. 708 * Or, this process may even be being swapped out again. 709 */ 710 if (p->p_flag & (P_INMEM | P_SWAPPINGOUT | P_SWAPPINGIN)) { 711 PROC_UNLOCK(p); 712 goto loop; 713 } 714 715 /* 716 * We would like to bring someone in. (only if there is space). 717 * [What checks the space? ] 718 */ 719 faultin(p); 720 PROC_UNLOCK(p); 721 goto loop; 722 } 723 724 /* 725 * First, if any processes have been sleeping or stopped for at least 726 * "swap_idle_threshold1" seconds, they are swapped out. If, however, 727 * no such processes exist, then the longest-sleeping or stopped 728 * process is swapped out. Finally, and only as a last resort, if 729 * there are no sleeping or stopped processes, the longest-resident 730 * process is swapped out. 731 */ 732 static void 733 swapout_procs(int action) 734 { 735 struct proc *p; 736 struct thread *td; 737 int didswap = 0; 738 739 retry: 740 sx_slock(&allproc_lock); 741 FOREACH_PROC_IN_SYSTEM(p) { 742 struct vmspace *vm; 743 int minslptime = 100000; 744 int slptime; 745 746 PROC_LOCK(p); 747 /* 748 * Watch out for a process in 749 * creation. It may have no 750 * address space or lock yet. 751 */ 752 if (p->p_state == PRS_NEW) { 753 PROC_UNLOCK(p); 754 continue; 755 } 756 /* 757 * An aio daemon switches its 758 * address space while running. 759 * Perform a quick check whether 760 * a process has P_SYSTEM. 761 * Filter out exiting processes. 762 */ 763 if ((p->p_flag & (P_SYSTEM | P_WEXIT)) != 0) { 764 PROC_UNLOCK(p); 765 continue; 766 } 767 _PHOLD_LITE(p); 768 PROC_UNLOCK(p); 769 sx_sunlock(&allproc_lock); 770 771 /* 772 * Do not swapout a process that 773 * is waiting for VM data 774 * structures as there is a possible 775 * deadlock. Test this first as 776 * this may block. 777 * 778 * Lock the map until swapout 779 * finishes, or a thread of this 780 * process may attempt to alter 781 * the map. 782 */ 783 vm = vmspace_acquire_ref(p); 784 if (vm == NULL) 785 goto nextproc2; 786 if (!vm_map_trylock(&vm->vm_map)) 787 goto nextproc1; 788 789 PROC_LOCK(p); 790 if (p->p_lock != 1 || (p->p_flag & (P_STOPPED_SINGLE | 791 P_TRACED | P_SYSTEM)) != 0) 792 goto nextproc; 793 794 /* 795 * only aiod changes vmspace, however it will be 796 * skipped because of the if statement above checking 797 * for P_SYSTEM 798 */ 799 if ((p->p_flag & (P_INMEM|P_SWAPPINGOUT|P_SWAPPINGIN)) != P_INMEM) 800 goto nextproc; 801 802 switch (p->p_state) { 803 default: 804 /* Don't swap out processes in any sort 805 * of 'special' state. */ 806 break; 807 808 case PRS_NORMAL: 809 /* 810 * do not swapout a realtime process 811 * Check all the thread groups.. 812 */ 813 FOREACH_THREAD_IN_PROC(p, td) { 814 thread_lock(td); 815 if (PRI_IS_REALTIME(td->td_pri_class)) { 816 thread_unlock(td); 817 goto nextproc; 818 } 819 slptime = (ticks - td->td_slptick) / hz; 820 /* 821 * Guarantee swap_idle_threshold1 822 * time in memory. 823 */ 824 if (slptime < swap_idle_threshold1) { 825 thread_unlock(td); 826 goto nextproc; 827 } 828 829 /* 830 * Do not swapout a process if it is 831 * waiting on a critical event of some 832 * kind or there is a thread whose 833 * pageable memory may be accessed. 834 * 835 * This could be refined to support 836 * swapping out a thread. 837 */ 838 if (!thread_safetoswapout(td)) { 839 thread_unlock(td); 840 goto nextproc; 841 } 842 /* 843 * If the system is under memory stress, 844 * or if we are swapping 845 * idle processes >= swap_idle_threshold2, 846 * then swap the process out. 847 */ 848 if (((action & VM_SWAP_NORMAL) == 0) && 849 (((action & VM_SWAP_IDLE) == 0) || 850 (slptime < swap_idle_threshold2))) { 851 thread_unlock(td); 852 goto nextproc; 853 } 854 855 if (minslptime > slptime) 856 minslptime = slptime; 857 thread_unlock(td); 858 } 859 860 /* 861 * If the pageout daemon didn't free enough pages, 862 * or if this process is idle and the system is 863 * configured to swap proactively, swap it out. 864 */ 865 if ((action & VM_SWAP_NORMAL) || 866 ((action & VM_SWAP_IDLE) && 867 (minslptime > swap_idle_threshold2))) { 868 _PRELE(p); 869 if (swapout(p) == 0) 870 didswap++; 871 PROC_UNLOCK(p); 872 vm_map_unlock(&vm->vm_map); 873 vmspace_free(vm); 874 goto retry; 875 } 876 } 877 nextproc: 878 PROC_UNLOCK(p); 879 vm_map_unlock(&vm->vm_map); 880 nextproc1: 881 vmspace_free(vm); 882 nextproc2: 883 sx_slock(&allproc_lock); 884 PRELE(p); 885 } 886 sx_sunlock(&allproc_lock); 887 /* 888 * If we swapped something out, and another process needed memory, 889 * then wakeup the sched process. 890 */ 891 if (didswap) 892 wakeup(&proc0); 893 } 894 895 static void 896 swapclear(struct proc *p) 897 { 898 struct thread *td; 899 900 PROC_LOCK_ASSERT(p, MA_OWNED); 901 902 FOREACH_THREAD_IN_PROC(p, td) { 903 thread_lock(td); 904 td->td_flags |= TDF_INMEM; 905 td->td_flags &= ~TDF_SWAPINREQ; 906 TD_CLR_SWAPPED(td); 907 if (TD_CAN_RUN(td)) 908 if (setrunnable(td)) { 909 #ifdef INVARIANTS 910 /* 911 * XXX: We just cleared TDI_SWAPPED 912 * above and set TDF_INMEM, so this 913 * should never happen. 914 */ 915 panic("not waking up swapper"); 916 #endif 917 } 918 thread_unlock(td); 919 } 920 p->p_flag &= ~(P_SWAPPINGIN | P_SWAPPINGOUT); 921 p->p_flag |= P_INMEM; 922 } 923 924 static int 925 swapout(struct proc *p) 926 { 927 struct thread *td; 928 929 PROC_LOCK_ASSERT(p, MA_OWNED); 930 931 /* 932 * The states of this process and its threads may have changed 933 * by now. Assuming that there is only one pageout daemon thread, 934 * this process should still be in memory. 935 */ 936 KASSERT((p->p_flag & (P_INMEM | P_SWAPPINGOUT | P_SWAPPINGIN)) == 937 P_INMEM, ("swapout: lost a swapout race?")); 938 939 /* 940 * remember the process resident count 941 */ 942 p->p_vmspace->vm_swrss = vmspace_resident_count(p->p_vmspace); 943 /* 944 * Check and mark all threads before we proceed. 945 */ 946 p->p_flag &= ~P_INMEM; 947 p->p_flag |= P_SWAPPINGOUT; 948 FOREACH_THREAD_IN_PROC(p, td) { 949 thread_lock(td); 950 if (!thread_safetoswapout(td)) { 951 thread_unlock(td); 952 swapclear(p); 953 return (EBUSY); 954 } 955 td->td_flags &= ~TDF_INMEM; 956 TD_SET_SWAPPED(td); 957 thread_unlock(td); 958 } 959 td = FIRST_THREAD_IN_PROC(p); 960 ++td->td_ru.ru_nswap; 961 PROC_UNLOCK(p); 962 963 /* 964 * This list is stable because all threads are now prevented from 965 * running. The list is only modified in the context of a running 966 * thread in this process. 967 */ 968 FOREACH_THREAD_IN_PROC(p, td) 969 vm_thread_swapout(td); 970 971 PROC_LOCK(p); 972 p->p_flag &= ~P_SWAPPINGOUT; 973 p->p_swtick = ticks; 974 return (0); 975 } 976