1 /* $NetBSD: uvm_pdaemon.c,v 1.76 2006/02/14 15:06:27 yamt Exp $ */ 2 3 /* 4 * Copyright (c) 1997 Charles D. Cranor and Washington University. 5 * Copyright (c) 1991, 1993, The Regents of the University of California. 6 * 7 * All rights reserved. 8 * 9 * This code is derived from software contributed to Berkeley by 10 * The Mach Operating System project at Carnegie-Mellon University. 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions and the following disclaimer. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in the 19 * documentation and/or other materials provided with the distribution. 20 * 3. All advertising materials mentioning features or use of this software 21 * must display the following acknowledgement: 22 * This product includes software developed by Charles D. Cranor, 23 * Washington University, the University of California, Berkeley and 24 * its contributors. 25 * 4. Neither the name of the University nor the names of its contributors 26 * may be used to endorse or promote products derived from this software 27 * without specific prior written permission. 28 * 29 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 30 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 31 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 32 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 33 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 34 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 35 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 36 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 37 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 38 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 39 * SUCH DAMAGE. 40 * 41 * @(#)vm_pageout.c 8.5 (Berkeley) 2/14/94 42 * from: Id: uvm_pdaemon.c,v 1.1.2.32 1998/02/06 05:26:30 chs Exp 43 * 44 * 45 * Copyright (c) 1987, 1990 Carnegie-Mellon University. 46 * All rights reserved. 47 * 48 * Permission to use, copy, modify and distribute this software and 49 * its documentation is hereby granted, provided that both the copyright 50 * notice and this permission notice appear in all copies of the 51 * software, derivative works or modified versions, and any portions 52 * thereof, and that both notices appear in supporting documentation. 53 * 54 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 55 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 56 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 57 * 58 * Carnegie Mellon requests users of this software to return to 59 * 60 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 61 * School of Computer Science 62 * Carnegie Mellon University 63 * Pittsburgh PA 15213-3890 64 * 65 * any improvements or extensions that they make and grant Carnegie the 66 * rights to redistribute these changes. 67 */ 68 69 /* 70 * uvm_pdaemon.c: the page daemon 71 */ 72 73 #include <sys/cdefs.h> 74 __KERNEL_RCSID(0, "$NetBSD: uvm_pdaemon.c,v 1.76 2006/02/14 15:06:27 yamt Exp $"); 75 76 #include "opt_uvmhist.h" 77 #include "opt_readahead.h" 78 79 #include <sys/param.h> 80 #include <sys/proc.h> 81 #include <sys/systm.h> 82 #include <sys/kernel.h> 83 #include <sys/pool.h> 84 #include <sys/buf.h> 85 #include <sys/vnode.h> 86 87 #include <uvm/uvm.h> 88 89 /* 90 * UVMPD_NUMDIRTYREACTS is how many dirty pages the pagedaemon will reactivate 91 * in a pass thru the inactive list when swap is full. the value should be 92 * "small"... if it's too large we'll cycle the active pages thru the inactive 93 * queue too quickly to for them to be referenced and avoid being freed. 94 */ 95 96 #define UVMPD_NUMDIRTYREACTS 16 97 98 99 /* 100 * local prototypes 101 */ 102 103 static void uvmpd_scan(void); 104 static void uvmpd_scan_inactive(struct pglist *); 105 static void uvmpd_tune(void); 106 107 /* 108 * XXX hack to avoid hangs when large processes fork. 109 */ 110 int uvm_extrapages; 111 112 /* 113 * uvm_wait: wait (sleep) for the page daemon to free some pages 114 * 115 * => should be called with all locks released 116 * => should _not_ be called by the page daemon (to avoid deadlock) 117 */ 118 119 void 120 uvm_wait(const char *wmsg) 121 { 122 int timo = 0; 123 int s = splbio(); 124 125 /* 126 * check for page daemon going to sleep (waiting for itself) 127 */ 128 129 if (curproc == uvm.pagedaemon_proc && uvmexp.paging == 0) { 130 /* 131 * now we have a problem: the pagedaemon wants to go to 132 * sleep until it frees more memory. but how can it 133 * free more memory if it is asleep? that is a deadlock. 134 * we have two options: 135 * [1] panic now 136 * [2] put a timeout on the sleep, thus causing the 137 * pagedaemon to only pause (rather than sleep forever) 138 * 139 * note that option [2] will only help us if we get lucky 140 * and some other process on the system breaks the deadlock 141 * by exiting or freeing memory (thus allowing the pagedaemon 142 * to continue). for now we panic if DEBUG is defined, 143 * otherwise we hope for the best with option [2] (better 144 * yet, this should never happen in the first place!). 145 */ 146 147 printf("pagedaemon: deadlock detected!\n"); 148 timo = hz >> 3; /* set timeout */ 149 #if defined(DEBUG) 150 /* DEBUG: panic so we can debug it */ 151 panic("pagedaemon deadlock"); 152 #endif 153 } 154 155 simple_lock(&uvm.pagedaemon_lock); 156 wakeup(&uvm.pagedaemon); /* wake the daemon! */ 157 UVM_UNLOCK_AND_WAIT(&uvmexp.free, &uvm.pagedaemon_lock, FALSE, wmsg, 158 timo); 159 160 splx(s); 161 } 162 163 164 /* 165 * uvmpd_tune: tune paging parameters 166 * 167 * => called when ever memory is added (or removed?) to the system 168 * => caller must call with page queues locked 169 */ 170 171 static void 172 uvmpd_tune(void) 173 { 174 UVMHIST_FUNC("uvmpd_tune"); UVMHIST_CALLED(pdhist); 175 176 uvmexp.freemin = uvmexp.npages / 20; 177 178 /* between 16k and 256k */ 179 /* XXX: what are these values good for? */ 180 uvmexp.freemin = MAX(uvmexp.freemin, (16*1024) >> PAGE_SHIFT); 181 uvmexp.freemin = MIN(uvmexp.freemin, (256*1024) >> PAGE_SHIFT); 182 183 /* Make sure there's always a user page free. */ 184 if (uvmexp.freemin < uvmexp.reserve_kernel + 1) 185 uvmexp.freemin = uvmexp.reserve_kernel + 1; 186 187 uvmexp.freetarg = (uvmexp.freemin * 4) / 3; 188 if (uvmexp.freetarg <= uvmexp.freemin) 189 uvmexp.freetarg = uvmexp.freemin + 1; 190 191 uvmexp.freetarg += uvm_extrapages; 192 uvm_extrapages = 0; 193 194 /* uvmexp.inactarg: computed in main daemon loop */ 195 196 uvmexp.wiredmax = uvmexp.npages / 3; 197 UVMHIST_LOG(pdhist, "<- done, freemin=%d, freetarg=%d, wiredmax=%d", 198 uvmexp.freemin, uvmexp.freetarg, uvmexp.wiredmax, 0); 199 } 200 201 /* 202 * uvm_pageout: the main loop for the pagedaemon 203 */ 204 205 void 206 uvm_pageout(void *arg) 207 { 208 int bufcnt, npages = 0; 209 int extrapages = 0; 210 UVMHIST_FUNC("uvm_pageout"); UVMHIST_CALLED(pdhist); 211 212 UVMHIST_LOG(pdhist,"<starting uvm pagedaemon>", 0, 0, 0, 0); 213 214 /* 215 * ensure correct priority and set paging parameters... 216 */ 217 218 uvm.pagedaemon_proc = curproc; 219 uvm_lock_pageq(); 220 npages = uvmexp.npages; 221 uvmpd_tune(); 222 uvm_unlock_pageq(); 223 224 /* 225 * main loop 226 */ 227 228 for (;;) { 229 simple_lock(&uvm.pagedaemon_lock); 230 231 UVMHIST_LOG(pdhist," <<SLEEPING>>",0,0,0,0); 232 UVM_UNLOCK_AND_WAIT(&uvm.pagedaemon, 233 &uvm.pagedaemon_lock, FALSE, "pgdaemon", 0); 234 uvmexp.pdwoke++; 235 UVMHIST_LOG(pdhist," <<WOKE UP>>",0,0,0,0); 236 237 /* 238 * now lock page queues and recompute inactive count 239 */ 240 241 uvm_lock_pageq(); 242 if (npages != uvmexp.npages || extrapages != uvm_extrapages) { 243 npages = uvmexp.npages; 244 extrapages = uvm_extrapages; 245 uvmpd_tune(); 246 } 247 248 uvmexp.inactarg = UVM_PCTPARAM_APPLY(&uvmexp.inactivepct, 249 uvmexp.active + uvmexp.inactive); 250 if (uvmexp.inactarg <= uvmexp.freetarg) { 251 uvmexp.inactarg = uvmexp.freetarg + 1; 252 } 253 254 /* 255 * Estimate a hint. Note that bufmem are returned to 256 * system only when entire pool page is empty. 257 */ 258 bufcnt = uvmexp.freetarg - uvmexp.free; 259 if (bufcnt < 0) 260 bufcnt = 0; 261 262 UVMHIST_LOG(pdhist," free/ftarg=%d/%d, inact/itarg=%d/%d", 263 uvmexp.free, uvmexp.freetarg, uvmexp.inactive, 264 uvmexp.inactarg); 265 266 /* 267 * scan if needed 268 */ 269 270 if (uvmexp.free + uvmexp.paging < uvmexp.freetarg || 271 uvmexp.inactive < uvmexp.inactarg) { 272 uvmpd_scan(); 273 } 274 275 /* 276 * if there's any free memory to be had, 277 * wake up any waiters. 278 */ 279 280 if (uvmexp.free > uvmexp.reserve_kernel || 281 uvmexp.paging == 0) { 282 wakeup(&uvmexp.free); 283 } 284 285 /* 286 * scan done. unlock page queues (the only lock we are holding) 287 */ 288 289 uvm_unlock_pageq(); 290 291 buf_drain(bufcnt << PAGE_SHIFT); 292 293 /* 294 * drain pool resources now that we're not holding any locks 295 */ 296 297 pool_drain(0); 298 299 /* 300 * free any cached u-areas we don't need 301 */ 302 uvm_uarea_drain(TRUE); 303 304 } 305 /*NOTREACHED*/ 306 } 307 308 309 /* 310 * uvm_aiodone_daemon: main loop for the aiodone daemon. 311 */ 312 313 void 314 uvm_aiodone_daemon(void *arg) 315 { 316 int s, free; 317 struct buf *bp, *nbp; 318 UVMHIST_FUNC("uvm_aiodoned"); UVMHIST_CALLED(pdhist); 319 320 for (;;) { 321 322 /* 323 * carefully attempt to go to sleep (without losing "wakeups"!). 324 * we need splbio because we want to make sure the aio_done list 325 * is totally empty before we go to sleep. 326 */ 327 328 s = splbio(); 329 simple_lock(&uvm.aiodoned_lock); 330 if (TAILQ_FIRST(&uvm.aio_done) == NULL) { 331 UVMHIST_LOG(pdhist," <<SLEEPING>>",0,0,0,0); 332 UVM_UNLOCK_AND_WAIT(&uvm.aiodoned, 333 &uvm.aiodoned_lock, FALSE, "aiodoned", 0); 334 UVMHIST_LOG(pdhist," <<WOKE UP>>",0,0,0,0); 335 336 /* relock aiodoned_lock, still at splbio */ 337 simple_lock(&uvm.aiodoned_lock); 338 } 339 340 /* 341 * check for done aio structures 342 */ 343 344 bp = TAILQ_FIRST(&uvm.aio_done); 345 if (bp) { 346 TAILQ_INIT(&uvm.aio_done); 347 } 348 349 simple_unlock(&uvm.aiodoned_lock); 350 splx(s); 351 352 /* 353 * process each i/o that's done. 354 */ 355 356 free = uvmexp.free; 357 while (bp != NULL) { 358 nbp = TAILQ_NEXT(bp, b_freelist); 359 (*bp->b_iodone)(bp); 360 bp = nbp; 361 } 362 if (free <= uvmexp.reserve_kernel) { 363 s = uvm_lock_fpageq(); 364 wakeup(&uvm.pagedaemon); 365 uvm_unlock_fpageq(s); 366 } else { 367 simple_lock(&uvm.pagedaemon_lock); 368 wakeup(&uvmexp.free); 369 simple_unlock(&uvm.pagedaemon_lock); 370 } 371 } 372 } 373 374 /* 375 * uvmpd_trylockowner: trylock the page's owner. 376 * 377 * => called with pageq locked. 378 * => resolve orphaned O->A loaned page. 379 * => return the locked simplelock on success. otherwise, return NULL. 380 */ 381 382 static struct simplelock * 383 uvmpd_trylockowner(struct vm_page *pg) 384 { 385 struct uvm_object *uobj = pg->uobject; 386 struct simplelock *slock; 387 388 UVM_LOCK_ASSERT_PAGEQ(); 389 if (uobj != NULL) { 390 slock = &uobj->vmobjlock; 391 } else { 392 struct vm_anon *anon = pg->uanon; 393 394 KASSERT(anon != NULL); 395 slock = &anon->an_lock; 396 } 397 398 if (!simple_lock_try(slock)) { 399 return NULL; 400 } 401 402 if (uobj == NULL) { 403 404 /* 405 * set PQ_ANON if it isn't set already. 406 */ 407 408 if ((pg->pqflags & PQ_ANON) == 0) { 409 KASSERT(pg->loan_count > 0); 410 pg->loan_count--; 411 pg->pqflags |= PQ_ANON; 412 /* anon now owns it */ 413 } 414 } 415 416 return slock; 417 } 418 419 #if defined(VMSWAP) 420 struct swapcluster { 421 int swc_slot; 422 int swc_nallocated; 423 int swc_nused; 424 struct vm_page *swc_pages[howmany(MAXPHYS, MIN_PAGE_SIZE)]; 425 }; 426 427 static void 428 swapcluster_init(struct swapcluster *swc) 429 { 430 431 swc->swc_slot = 0; 432 } 433 434 static int 435 swapcluster_allocslots(struct swapcluster *swc) 436 { 437 int slot; 438 int npages; 439 440 if (swc->swc_slot != 0) { 441 return 0; 442 } 443 444 /* Even with strange MAXPHYS, the shift 445 implicitly rounds down to a page. */ 446 npages = MAXPHYS >> PAGE_SHIFT; 447 slot = uvm_swap_alloc(&npages, TRUE); 448 if (slot == 0) { 449 return ENOMEM; 450 } 451 swc->swc_slot = slot; 452 swc->swc_nallocated = npages; 453 swc->swc_nused = 0; 454 455 return 0; 456 } 457 458 static int 459 swapcluster_add(struct swapcluster *swc, struct vm_page *pg) 460 { 461 int slot; 462 struct uvm_object *uobj; 463 464 KASSERT(swc->swc_slot != 0); 465 KASSERT(swc->swc_nused < swc->swc_nallocated); 466 KASSERT((pg->pqflags & PQ_SWAPBACKED) != 0); 467 468 slot = swc->swc_slot + swc->swc_nused; 469 uobj = pg->uobject; 470 if (uobj == NULL) { 471 LOCK_ASSERT(simple_lock_held(&pg->uanon->an_lock)); 472 pg->uanon->an_swslot = slot; 473 } else { 474 int result; 475 476 LOCK_ASSERT(simple_lock_held(&uobj->vmobjlock)); 477 result = uao_set_swslot(uobj, pg->offset >> PAGE_SHIFT, slot); 478 if (result == -1) { 479 return ENOMEM; 480 } 481 } 482 swc->swc_pages[swc->swc_nused] = pg; 483 swc->swc_nused++; 484 485 return 0; 486 } 487 488 static void 489 swapcluster_flush(struct swapcluster *swc, boolean_t now) 490 { 491 int slot; 492 int nused; 493 int nallocated; 494 int error; 495 496 if (swc->swc_slot == 0) { 497 return; 498 } 499 KASSERT(swc->swc_nused <= swc->swc_nallocated); 500 501 slot = swc->swc_slot; 502 nused = swc->swc_nused; 503 nallocated = swc->swc_nallocated; 504 505 /* 506 * if this is the final pageout we could have a few 507 * unused swap blocks. if so, free them now. 508 */ 509 510 if (nused < nallocated) { 511 if (!now) { 512 return; 513 } 514 uvm_swap_free(slot + nused, nallocated - nused); 515 } 516 517 /* 518 * now start the pageout. 519 */ 520 521 uvmexp.pdpageouts++; 522 error = uvm_swap_put(slot, swc->swc_pages, nused, 0); 523 KASSERT(error == 0); 524 525 /* 526 * zero swslot to indicate that we are 527 * no longer building a swap-backed cluster. 528 */ 529 530 swc->swc_slot = 0; 531 } 532 #endif /* defined(VMSWAP) */ 533 534 /* 535 * uvmpd_scan_inactive: scan an inactive list for pages to clean or free. 536 * 537 * => called with page queues locked 538 * => we work on meeting our free target by converting inactive pages 539 * into free pages. 540 * => we handle the building of swap-backed clusters 541 */ 542 543 static void 544 uvmpd_scan_inactive(struct pglist *pglst) 545 { 546 struct vm_page *p, *nextpg = NULL; /* Quell compiler warning */ 547 struct uvm_object *uobj; 548 struct vm_anon *anon; 549 #if defined(VMSWAP) 550 struct swapcluster swc; 551 #endif /* defined(VMSWAP) */ 552 struct simplelock *slock; 553 int dirtyreacts, t; 554 boolean_t anonunder, fileunder, execunder; 555 boolean_t anonover, fileover, execover; 556 boolean_t anonreact, filereact, execreact; 557 UVMHIST_FUNC("uvmpd_scan_inactive"); UVMHIST_CALLED(pdhist); 558 559 /* 560 * swslot is non-zero if we are building a swap cluster. we want 561 * to stay in the loop while we have a page to scan or we have 562 * a swap-cluster to build. 563 */ 564 565 #if defined(VMSWAP) 566 swapcluster_init(&swc); 567 #endif /* defined(VMSWAP) */ 568 dirtyreacts = 0; 569 570 /* 571 * decide which types of pages we want to reactivate instead of freeing 572 * to keep usage within the minimum and maximum usage limits. 573 */ 574 575 t = uvmexp.active + uvmexp.inactive + uvmexp.free; 576 anonunder = (uvmexp.anonpages <= (t * uvmexp.anonmin) >> 8); 577 fileunder = (uvmexp.filepages <= (t * uvmexp.filemin) >> 8); 578 execunder = (uvmexp.execpages <= (t * uvmexp.execmin) >> 8); 579 anonover = uvmexp.anonpages > ((t * uvmexp.anonmax) >> 8); 580 fileover = uvmexp.filepages > ((t * uvmexp.filemax) >> 8); 581 execover = uvmexp.execpages > ((t * uvmexp.execmax) >> 8); 582 anonreact = anonunder || (!anonover && (fileover || execover)); 583 filereact = fileunder || (!fileover && (anonover || execover)); 584 execreact = execunder || (!execover && (anonover || fileover)); 585 if (filereact && execreact && (anonreact || uvm_swapisfull())) { 586 anonreact = filereact = execreact = FALSE; 587 } 588 #if !defined(VMSWAP) 589 /* 590 * XXX no point to put swap-backed pages on the page queue. 591 */ 592 593 anonreact = TRUE; 594 #endif /* !defined(VMSWAP) */ 595 for (p = TAILQ_FIRST(pglst); p != NULL; p = nextpg) { 596 uobj = NULL; 597 anon = NULL; 598 599 /* 600 * see if we've met the free target. 601 */ 602 603 if (uvmexp.free + uvmexp.paging >= uvmexp.freetarg << 2 || 604 dirtyreacts == UVMPD_NUMDIRTYREACTS) { 605 UVMHIST_LOG(pdhist," met free target: " 606 "exit loop", 0, 0, 0, 0); 607 break; 608 } 609 610 /* 611 * we are below target and have a new page to consider. 612 */ 613 614 uvmexp.pdscans++; 615 nextpg = TAILQ_NEXT(p, pageq); 616 617 /* 618 * move referenced pages back to active queue and 619 * skip to next page. 620 */ 621 622 if (pmap_is_referenced(p)) { 623 uvm_pageactivate(p); 624 uvmexp.pdreact++; 625 continue; 626 } 627 anon = p->uanon; 628 uobj = p->uobject; 629 630 /* 631 * enforce the minimum thresholds on different 632 * types of memory usage. if reusing the current 633 * page would reduce that type of usage below its 634 * minimum, reactivate the page instead and move 635 * on to the next page. 636 */ 637 638 if (uobj && UVM_OBJ_IS_VTEXT(uobj) && execreact) { 639 uvm_pageactivate(p); 640 uvmexp.pdreexec++; 641 continue; 642 } 643 if (uobj && UVM_OBJ_IS_VNODE(uobj) && 644 !UVM_OBJ_IS_VTEXT(uobj) && filereact) { 645 uvm_pageactivate(p); 646 uvmexp.pdrefile++; 647 continue; 648 } 649 if ((anon || UVM_OBJ_IS_AOBJ(uobj)) && anonreact) { 650 uvm_pageactivate(p); 651 uvmexp.pdreanon++; 652 continue; 653 } 654 655 /* 656 * first we attempt to lock the object that this page 657 * belongs to. if our attempt fails we skip on to 658 * the next page (no harm done). it is important to 659 * "try" locking the object as we are locking in the 660 * wrong order (pageq -> object) and we don't want to 661 * deadlock. 662 * 663 * the only time we expect to see an ownerless page 664 * (i.e. a page with no uobject and !PQ_ANON) is if an 665 * anon has loaned a page from a uvm_object and the 666 * uvm_object has dropped the ownership. in that 667 * case, the anon can "take over" the loaned page 668 * and make it its own. 669 */ 670 671 slock = uvmpd_trylockowner(p); 672 if (slock == NULL) { 673 continue; 674 } 675 if (p->flags & PG_BUSY) { 676 simple_unlock(slock); 677 uvmexp.pdbusy++; 678 continue; 679 } 680 681 /* does the page belong to an object? */ 682 if (uobj != NULL) { 683 uvmexp.pdobscan++; 684 } else { 685 #if defined(VMSWAP) 686 KASSERT(anon != NULL); 687 uvmexp.pdanscan++; 688 #else /* defined(VMSWAP) */ 689 panic("%s: anon", __func__); 690 #endif /* defined(VMSWAP) */ 691 } 692 693 694 /* 695 * we now have the object and the page queues locked. 696 * if the page is not swap-backed, call the object's 697 * pager to flush and free the page. 698 */ 699 700 #if defined(READAHEAD_STATS) 701 if ((p->flags & PG_SPECULATIVE) != 0) { 702 p->flags &= ~PG_SPECULATIVE; 703 uvm_ra_miss.ev_count++; 704 } 705 #endif /* defined(READAHEAD_STATS) */ 706 707 if ((p->pqflags & PQ_SWAPBACKED) == 0) { 708 uvm_unlock_pageq(); 709 (void) (uobj->pgops->pgo_put)(uobj, p->offset, 710 p->offset + PAGE_SIZE, PGO_CLEANIT|PGO_FREE); 711 uvm_lock_pageq(); 712 if (nextpg && 713 (nextpg->pqflags & PQ_INACTIVE) == 0) { 714 nextpg = TAILQ_FIRST(pglst); 715 } 716 continue; 717 } 718 719 #if defined(VMSWAP) 720 /* 721 * the page is swap-backed. remove all the permissions 722 * from the page so we can sync the modified info 723 * without any race conditions. if the page is clean 724 * we can free it now and continue. 725 */ 726 727 pmap_page_protect(p, VM_PROT_NONE); 728 if ((p->flags & PG_CLEAN) && pmap_clear_modify(p)) { 729 p->flags &= ~(PG_CLEAN); 730 } 731 if (p->flags & PG_CLEAN) { 732 int slot; 733 int pageidx; 734 735 pageidx = p->offset >> PAGE_SHIFT; 736 uvm_pagefree(p); 737 uvmexp.pdfreed++; 738 739 /* 740 * for anons, we need to remove the page 741 * from the anon ourselves. for aobjs, 742 * pagefree did that for us. 743 */ 744 745 if (anon) { 746 KASSERT(anon->an_swslot != 0); 747 anon->an_page = NULL; 748 slot = anon->an_swslot; 749 } else { 750 slot = uao_find_swslot(uobj, pageidx); 751 } 752 simple_unlock(slock); 753 754 if (slot > 0) { 755 /* this page is now only in swap. */ 756 simple_lock(&uvm.swap_data_lock); 757 KASSERT(uvmexp.swpgonly < uvmexp.swpginuse); 758 uvmexp.swpgonly++; 759 simple_unlock(&uvm.swap_data_lock); 760 } 761 continue; 762 } 763 764 /* 765 * this page is dirty, skip it if we'll have met our 766 * free target when all the current pageouts complete. 767 */ 768 769 if (uvmexp.free + uvmexp.paging > uvmexp.freetarg << 2) { 770 simple_unlock(slock); 771 continue; 772 } 773 774 /* 775 * free any swap space allocated to the page since 776 * we'll have to write it again with its new data. 777 */ 778 779 if ((p->pqflags & PQ_ANON) && anon->an_swslot) { 780 uvm_swap_free(anon->an_swslot, 1); 781 anon->an_swslot = 0; 782 } else if (p->pqflags & PQ_AOBJ) { 783 uao_dropswap(uobj, p->offset >> PAGE_SHIFT); 784 } 785 786 /* 787 * if all pages in swap are only in swap, 788 * the swap space is full and we can't page out 789 * any more swap-backed pages. reactivate this page 790 * so that we eventually cycle all pages through 791 * the inactive queue. 792 */ 793 794 if (uvm_swapisfull()) { 795 dirtyreacts++; 796 uvm_pageactivate(p); 797 simple_unlock(slock); 798 continue; 799 } 800 801 /* 802 * start new swap pageout cluster (if necessary). 803 */ 804 805 if (swapcluster_allocslots(&swc)) { 806 simple_unlock(slock); 807 continue; 808 } 809 810 /* 811 * at this point, we're definitely going reuse this 812 * page. mark the page busy and delayed-free. 813 * we should remove the page from the page queues 814 * so we don't ever look at it again. 815 * adjust counters and such. 816 */ 817 818 p->flags |= PG_BUSY; 819 UVM_PAGE_OWN(p, "scan_inactive"); 820 821 p->flags |= PG_PAGEOUT; 822 uvmexp.paging++; 823 uvm_pagedequeue(p); 824 825 uvmexp.pgswapout++; 826 uvm_unlock_pageq(); 827 828 /* 829 * add the new page to the cluster. 830 */ 831 832 if (swapcluster_add(&swc, p)) { 833 p->flags &= ~(PG_BUSY|PG_PAGEOUT); 834 UVM_PAGE_OWN(p, NULL); 835 uvm_lock_pageq(); 836 uvmexp.paging--; 837 uvm_pageactivate(p); 838 simple_unlock(slock); 839 continue; 840 } 841 simple_unlock(slock); 842 843 swapcluster_flush(&swc, FALSE); 844 uvm_lock_pageq(); 845 846 #else /* defined(VMSWAP) */ 847 panic("%s: swap-backed", __func__); 848 #endif /* defined(VMSWAP) */ 849 850 /* 851 * the pageout is in progress. bump counters and set up 852 * for the next loop. 853 */ 854 855 uvmexp.pdpending++; 856 if (nextpg && (nextpg->pqflags & PQ_INACTIVE) == 0) { 857 nextpg = TAILQ_FIRST(pglst); 858 } 859 } 860 861 #if defined(VMSWAP) 862 uvm_unlock_pageq(); 863 swapcluster_flush(&swc, TRUE); 864 uvm_lock_pageq(); 865 #endif /* defined(VMSWAP) */ 866 } 867 868 /* 869 * uvmpd_scan: scan the page queues and attempt to meet our targets. 870 * 871 * => called with pageq's locked 872 */ 873 874 static void 875 uvmpd_scan(void) 876 { 877 int inactive_shortage, swap_shortage, pages_freed; 878 struct vm_page *p, *nextpg; 879 struct simplelock *slock; 880 UVMHIST_FUNC("uvmpd_scan"); UVMHIST_CALLED(pdhist); 881 882 uvmexp.pdrevs++; 883 884 #ifndef __SWAP_BROKEN 885 886 /* 887 * swap out some processes if we are below our free target. 888 * we need to unlock the page queues for this. 889 */ 890 891 if (uvmexp.free < uvmexp.freetarg && uvmexp.nswapdev != 0) { 892 uvmexp.pdswout++; 893 UVMHIST_LOG(pdhist," free %d < target %d: swapout", 894 uvmexp.free, uvmexp.freetarg, 0, 0); 895 uvm_unlock_pageq(); 896 uvm_swapout_threads(); 897 uvm_lock_pageq(); 898 899 } 900 #endif 901 902 /* 903 * now we want to work on meeting our targets. first we work on our 904 * free target by converting inactive pages into free pages. then 905 * we work on meeting our inactive target by converting active pages 906 * to inactive ones. 907 */ 908 909 UVMHIST_LOG(pdhist, " starting 'free' loop",0,0,0,0); 910 911 pages_freed = uvmexp.pdfreed; 912 uvmpd_scan_inactive(&uvm.page_inactive); 913 pages_freed = uvmexp.pdfreed - pages_freed; 914 915 /* 916 * we have done the scan to get free pages. now we work on meeting 917 * our inactive target. 918 */ 919 920 inactive_shortage = uvmexp.inactarg - uvmexp.inactive; 921 922 /* 923 * detect if we're not going to be able to page anything out 924 * until we free some swap resources from active pages. 925 */ 926 927 swap_shortage = 0; 928 if (uvmexp.free < uvmexp.freetarg && 929 uvmexp.swpginuse >= uvmexp.swpgavail && 930 !uvm_swapisfull() && 931 pages_freed == 0) { 932 swap_shortage = uvmexp.freetarg - uvmexp.free; 933 } 934 935 UVMHIST_LOG(pdhist, " loop 2: inactive_shortage=%d swap_shortage=%d", 936 inactive_shortage, swap_shortage,0,0); 937 for (p = TAILQ_FIRST(&uvm.page_active); 938 p != NULL && (inactive_shortage > 0 || swap_shortage > 0); 939 p = nextpg) { 940 nextpg = TAILQ_NEXT(p, pageq); 941 if (p->flags & PG_BUSY) { 942 continue; 943 } 944 945 /* 946 * lock the page's owner. 947 */ 948 949 slock = uvmpd_trylockowner(p); 950 if (slock == NULL) { 951 continue; 952 } 953 954 /* 955 * skip this page if it's busy. 956 */ 957 958 if ((p->flags & PG_BUSY) != 0) { 959 simple_unlock(slock); 960 continue; 961 } 962 963 #if defined(VMSWAP) 964 /* 965 * if there's a shortage of swap, free any swap allocated 966 * to this page so that other pages can be paged out. 967 */ 968 969 if (swap_shortage > 0) { 970 struct vm_anon *anon = p->uanon; 971 972 if ((p->pqflags & PQ_ANON) && anon->an_swslot) { 973 uvm_swap_free(anon->an_swslot, 1); 974 anon->an_swslot = 0; 975 p->flags &= ~PG_CLEAN; 976 swap_shortage--; 977 } else if (p->pqflags & PQ_AOBJ) { 978 int slot = uao_set_swslot(p->uobject, 979 p->offset >> PAGE_SHIFT, 0); 980 if (slot) { 981 uvm_swap_free(slot, 1); 982 p->flags &= ~PG_CLEAN; 983 swap_shortage--; 984 } 985 } 986 } 987 #endif /* defined(VMSWAP) */ 988 989 /* 990 * if there's a shortage of inactive pages, deactivate. 991 */ 992 993 if (inactive_shortage > 0) { 994 /* no need to check wire_count as pg is "active" */ 995 pmap_clear_reference(p); 996 uvm_pagedeactivate(p); 997 uvmexp.pddeact++; 998 inactive_shortage--; 999 } 1000 1001 /* 1002 * we're done with this page. 1003 */ 1004 1005 simple_unlock(slock); 1006 } 1007 } 1008 1009 /* 1010 * uvm_reclaimable: decide whether to wait for pagedaemon. 1011 * 1012 * => return TRUE if it seems to be worth to do uvm_wait. 1013 * 1014 * XXX should be tunable. 1015 * XXX should consider pools, etc? 1016 */ 1017 1018 boolean_t 1019 uvm_reclaimable(void) 1020 { 1021 int filepages; 1022 1023 /* 1024 * if swap is not full, no problem. 1025 */ 1026 1027 if (!uvm_swapisfull()) { 1028 return TRUE; 1029 } 1030 1031 /* 1032 * file-backed pages can be reclaimed even when swap is full. 1033 * if we have more than 1/16 of pageable memory or 5MB, try to reclaim. 1034 * 1035 * XXX assume the worst case, ie. all wired pages are file-backed. 1036 * 1037 * XXX should consider about other reclaimable memory. 1038 * XXX ie. pools, traditional buffer cache. 1039 */ 1040 1041 filepages = uvmexp.filepages + uvmexp.execpages - uvmexp.wired; 1042 if (filepages >= MIN((uvmexp.active + uvmexp.inactive) >> 4, 1043 5 * 1024 * 1024 >> PAGE_SHIFT)) { 1044 return TRUE; 1045 } 1046 1047 /* 1048 * kill the process, fail allocation, etc.. 1049 */ 1050 1051 return FALSE; 1052 } 1053