1 /* $NetBSD: uvm_pdaemon.c,v 1.69 2005/11/29 15:45:28 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 1.69 2005/11/29 15:45:28 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 = (uvmexp.active + uvmexp.inactive) / 3; 249 if (uvmexp.inactarg <= uvmexp.freetarg) { 250 uvmexp.inactarg = uvmexp.freetarg + 1; 251 } 252 253 /* 254 * Estimate a hint. Note that bufmem are returned to 255 * system only when entire pool page is empty. 256 */ 257 bufcnt = uvmexp.freetarg - uvmexp.free; 258 if (bufcnt < 0) 259 bufcnt = 0; 260 261 UVMHIST_LOG(pdhist," free/ftarg=%d/%d, inact/itarg=%d/%d", 262 uvmexp.free, uvmexp.freetarg, uvmexp.inactive, 263 uvmexp.inactarg); 264 265 /* 266 * scan if needed 267 */ 268 269 if (uvmexp.free + uvmexp.paging < uvmexp.freetarg || 270 uvmexp.inactive < uvmexp.inactarg) { 271 uvmpd_scan(); 272 } 273 274 /* 275 * if there's any free memory to be had, 276 * wake up any waiters. 277 */ 278 279 if (uvmexp.free > uvmexp.reserve_kernel || 280 uvmexp.paging == 0) { 281 wakeup(&uvmexp.free); 282 } 283 284 /* 285 * scan done. unlock page queues (the only lock we are holding) 286 */ 287 288 uvm_unlock_pageq(); 289 290 buf_drain(bufcnt << PAGE_SHIFT); 291 292 /* 293 * drain pool resources now that we're not holding any locks 294 */ 295 296 pool_drain(0); 297 298 /* 299 * free any cached u-areas we don't need 300 */ 301 uvm_uarea_drain(TRUE); 302 303 } 304 /*NOTREACHED*/ 305 } 306 307 308 /* 309 * uvm_aiodone_daemon: main loop for the aiodone daemon. 310 */ 311 312 void 313 uvm_aiodone_daemon(void *arg) 314 { 315 int s, free; 316 struct buf *bp, *nbp; 317 UVMHIST_FUNC("uvm_aiodoned"); UVMHIST_CALLED(pdhist); 318 319 for (;;) { 320 321 /* 322 * carefully attempt to go to sleep (without losing "wakeups"!). 323 * we need splbio because we want to make sure the aio_done list 324 * is totally empty before we go to sleep. 325 */ 326 327 s = splbio(); 328 simple_lock(&uvm.aiodoned_lock); 329 if (TAILQ_FIRST(&uvm.aio_done) == NULL) { 330 UVMHIST_LOG(pdhist," <<SLEEPING>>",0,0,0,0); 331 UVM_UNLOCK_AND_WAIT(&uvm.aiodoned, 332 &uvm.aiodoned_lock, FALSE, "aiodoned", 0); 333 UVMHIST_LOG(pdhist," <<WOKE UP>>",0,0,0,0); 334 335 /* relock aiodoned_lock, still at splbio */ 336 simple_lock(&uvm.aiodoned_lock); 337 } 338 339 /* 340 * check for done aio structures 341 */ 342 343 bp = TAILQ_FIRST(&uvm.aio_done); 344 if (bp) { 345 TAILQ_INIT(&uvm.aio_done); 346 } 347 348 simple_unlock(&uvm.aiodoned_lock); 349 splx(s); 350 351 /* 352 * process each i/o that's done. 353 */ 354 355 free = uvmexp.free; 356 while (bp != NULL) { 357 nbp = TAILQ_NEXT(bp, b_freelist); 358 (*bp->b_iodone)(bp); 359 bp = nbp; 360 } 361 if (free <= uvmexp.reserve_kernel) { 362 s = uvm_lock_fpageq(); 363 wakeup(&uvm.pagedaemon); 364 uvm_unlock_fpageq(s); 365 } else { 366 simple_lock(&uvm.pagedaemon_lock); 367 wakeup(&uvmexp.free); 368 simple_unlock(&uvm.pagedaemon_lock); 369 } 370 } 371 } 372 373 /* 374 * uvmpd_scan_inactive: scan an inactive list for pages to clean or free. 375 * 376 * => called with page queues locked 377 * => we work on meeting our free target by converting inactive pages 378 * into free pages. 379 * => we handle the building of swap-backed clusters 380 * => we return TRUE if we are exiting because we met our target 381 */ 382 383 static void 384 uvmpd_scan_inactive(struct pglist *pglst) 385 { 386 struct vm_page *p, *nextpg = NULL; /* Quell compiler warning */ 387 struct uvm_object *uobj; 388 struct vm_anon *anon; 389 #if defined(VMSWAP) 390 struct vm_page *swpps[round_page(MAXPHYS) >> PAGE_SHIFT]; 391 int error; 392 int result; 393 #endif /* defined(VMSWAP) */ 394 struct simplelock *slock; 395 int swnpages, swcpages; 396 int swslot; 397 int dirtyreacts, t; 398 boolean_t anonunder, fileunder, execunder; 399 boolean_t anonover, fileover, execover; 400 boolean_t anonreact, filereact, execreact; 401 UVMHIST_FUNC("uvmpd_scan_inactive"); UVMHIST_CALLED(pdhist); 402 403 /* 404 * swslot is non-zero if we are building a swap cluster. we want 405 * to stay in the loop while we have a page to scan or we have 406 * a swap-cluster to build. 407 */ 408 409 swslot = 0; 410 swnpages = swcpages = 0; 411 dirtyreacts = 0; 412 413 /* 414 * decide which types of pages we want to reactivate instead of freeing 415 * to keep usage within the minimum and maximum usage limits. 416 */ 417 418 t = uvmexp.active + uvmexp.inactive + uvmexp.free; 419 anonunder = (uvmexp.anonpages <= (t * uvmexp.anonmin) >> 8); 420 fileunder = (uvmexp.filepages <= (t * uvmexp.filemin) >> 8); 421 execunder = (uvmexp.execpages <= (t * uvmexp.execmin) >> 8); 422 anonover = uvmexp.anonpages > ((t * uvmexp.anonmax) >> 8); 423 fileover = uvmexp.filepages > ((t * uvmexp.filemax) >> 8); 424 execover = uvmexp.execpages > ((t * uvmexp.execmax) >> 8); 425 anonreact = anonunder || (!anonover && (fileover || execover)); 426 filereact = fileunder || (!fileover && (anonover || execover)); 427 execreact = execunder || (!execover && (anonover || fileover)); 428 if (filereact && execreact && (anonreact || uvm_swapisfull())) { 429 anonreact = filereact = execreact = FALSE; 430 } 431 #if !defined(VMSWAP) 432 /* 433 * XXX no point to put swap-backed pages on the page queue. 434 */ 435 436 anonreact = TRUE; 437 #endif /* !defined(VMSWAP) */ 438 for (p = TAILQ_FIRST(pglst); p != NULL || swslot != 0; p = nextpg) { 439 uobj = NULL; 440 anon = NULL; 441 if (p) { 442 443 /* 444 * see if we've met the free target. 445 */ 446 447 if (uvmexp.free + uvmexp.paging >= 448 uvmexp.freetarg << 2 || 449 dirtyreacts == UVMPD_NUMDIRTYREACTS) { 450 UVMHIST_LOG(pdhist," met free target: " 451 "exit loop", 0, 0, 0, 0); 452 453 if (swslot == 0) { 454 /* exit now if no swap-i/o pending */ 455 break; 456 } 457 458 /* set p to null to signal final swap i/o */ 459 p = NULL; 460 nextpg = NULL; 461 } 462 } 463 if (p) { /* if (we have a new page to consider) */ 464 465 /* 466 * we are below target and have a new page to consider. 467 */ 468 469 uvmexp.pdscans++; 470 nextpg = TAILQ_NEXT(p, pageq); 471 472 /* 473 * move referenced pages back to active queue and 474 * skip to next page. 475 */ 476 477 if (pmap_clear_reference(p)) { 478 uvm_pageactivate(p); 479 uvmexp.pdreact++; 480 continue; 481 } 482 anon = p->uanon; 483 uobj = p->uobject; 484 485 /* 486 * enforce the minimum thresholds on different 487 * types of memory usage. if reusing the current 488 * page would reduce that type of usage below its 489 * minimum, reactivate the page instead and move 490 * on to the next page. 491 */ 492 493 if (uobj && UVM_OBJ_IS_VTEXT(uobj) && execreact) { 494 uvm_pageactivate(p); 495 uvmexp.pdreexec++; 496 continue; 497 } 498 if (uobj && UVM_OBJ_IS_VNODE(uobj) && 499 !UVM_OBJ_IS_VTEXT(uobj) && filereact) { 500 uvm_pageactivate(p); 501 uvmexp.pdrefile++; 502 continue; 503 } 504 if ((anon || UVM_OBJ_IS_AOBJ(uobj)) && anonreact) { 505 uvm_pageactivate(p); 506 uvmexp.pdreanon++; 507 continue; 508 } 509 510 /* 511 * first we attempt to lock the object that this page 512 * belongs to. if our attempt fails we skip on to 513 * the next page (no harm done). it is important to 514 * "try" locking the object as we are locking in the 515 * wrong order (pageq -> object) and we don't want to 516 * deadlock. 517 * 518 * the only time we expect to see an ownerless page 519 * (i.e. a page with no uobject and !PQ_ANON) is if an 520 * anon has loaned a page from a uvm_object and the 521 * uvm_object has dropped the ownership. in that 522 * case, the anon can "take over" the loaned page 523 * and make it its own. 524 */ 525 526 /* does the page belong to an object? */ 527 if (uobj != NULL) { 528 slock = &uobj->vmobjlock; 529 if (!simple_lock_try(slock)) { 530 continue; 531 } 532 if (p->flags & PG_BUSY) { 533 simple_unlock(slock); 534 uvmexp.pdbusy++; 535 continue; 536 } 537 uvmexp.pdobscan++; 538 } else { 539 #if defined(VMSWAP) 540 KASSERT(anon != NULL); 541 slock = &anon->an_lock; 542 if (!simple_lock_try(slock)) { 543 continue; 544 } 545 546 /* 547 * set PQ_ANON if it isn't set already. 548 */ 549 550 if ((p->pqflags & PQ_ANON) == 0) { 551 KASSERT(p->loan_count > 0); 552 p->loan_count--; 553 p->pqflags |= PQ_ANON; 554 /* anon now owns it */ 555 } 556 if (p->flags & PG_BUSY) { 557 simple_unlock(slock); 558 uvmexp.pdbusy++; 559 continue; 560 } 561 uvmexp.pdanscan++; 562 #else /* defined(VMSWAP) */ 563 panic("%s: anon", __func__); 564 #endif /* defined(VMSWAP) */ 565 } 566 567 568 /* 569 * we now have the object and the page queues locked. 570 * if the page is not swap-backed, call the object's 571 * pager to flush and free the page. 572 */ 573 574 #if defined(READAHEAD_STATS) 575 if ((p->flags & PG_SPECULATIVE) != 0) { 576 p->flags &= ~PG_SPECULATIVE; 577 uvm_ra_miss.ev_count++; 578 } 579 #endif /* defined(READAHEAD_STATS) */ 580 581 if ((p->pqflags & PQ_SWAPBACKED) == 0) { 582 uvm_unlock_pageq(); 583 (void) (uobj->pgops->pgo_put)(uobj, p->offset, 584 p->offset + PAGE_SIZE, 585 PGO_CLEANIT|PGO_FREE); 586 uvm_lock_pageq(); 587 if (nextpg && 588 (nextpg->pqflags & PQ_INACTIVE) == 0) { 589 nextpg = TAILQ_FIRST(pglst); 590 } 591 continue; 592 } 593 594 #if defined(VMSWAP) 595 /* 596 * the page is swap-backed. remove all the permissions 597 * from the page so we can sync the modified info 598 * without any race conditions. if the page is clean 599 * we can free it now and continue. 600 */ 601 602 pmap_page_protect(p, VM_PROT_NONE); 603 if ((p->flags & PG_CLEAN) && pmap_clear_modify(p)) { 604 p->flags &= ~(PG_CLEAN); 605 } 606 if (p->flags & PG_CLEAN) { 607 int slot; 608 int pageidx; 609 610 pageidx = p->offset >> PAGE_SHIFT; 611 uvm_pagefree(p); 612 uvmexp.pdfreed++; 613 614 /* 615 * for anons, we need to remove the page 616 * from the anon ourselves. for aobjs, 617 * pagefree did that for us. 618 */ 619 620 if (anon) { 621 KASSERT(anon->an_swslot != 0); 622 anon->an_page = NULL; 623 slot = anon->an_swslot; 624 } else { 625 slot = uao_find_swslot(uobj, pageidx); 626 } 627 simple_unlock(slock); 628 629 if (slot > 0) { 630 /* this page is now only in swap. */ 631 simple_lock(&uvm.swap_data_lock); 632 KASSERT(uvmexp.swpgonly < 633 uvmexp.swpginuse); 634 uvmexp.swpgonly++; 635 simple_unlock(&uvm.swap_data_lock); 636 } 637 continue; 638 } 639 640 /* 641 * this page is dirty, skip it if we'll have met our 642 * free target when all the current pageouts complete. 643 */ 644 645 if (uvmexp.free + uvmexp.paging > 646 uvmexp.freetarg << 2) { 647 simple_unlock(slock); 648 continue; 649 } 650 651 /* 652 * free any swap space allocated to the page since 653 * we'll have to write it again with its new data. 654 */ 655 656 if ((p->pqflags & PQ_ANON) && anon->an_swslot) { 657 uvm_swap_free(anon->an_swslot, 1); 658 anon->an_swslot = 0; 659 } else if (p->pqflags & PQ_AOBJ) { 660 uao_dropswap(uobj, p->offset >> PAGE_SHIFT); 661 } 662 663 /* 664 * if all pages in swap are only in swap, 665 * the swap space is full and we can't page out 666 * any more swap-backed pages. reactivate this page 667 * so that we eventually cycle all pages through 668 * the inactive queue. 669 */ 670 671 if (uvm_swapisfull()) { 672 dirtyreacts++; 673 uvm_pageactivate(p); 674 simple_unlock(slock); 675 continue; 676 } 677 678 /* 679 * start new swap pageout cluster (if necessary). 680 */ 681 682 if (swslot == 0) { 683 /* Even with strange MAXPHYS, the shift 684 implicitly rounds down to a page. */ 685 swnpages = MAXPHYS >> PAGE_SHIFT; 686 swslot = uvm_swap_alloc(&swnpages, TRUE); 687 if (swslot == 0) { 688 simple_unlock(slock); 689 continue; 690 } 691 swcpages = 0; 692 } 693 694 /* 695 * at this point, we're definitely going reuse this 696 * page. mark the page busy and delayed-free. 697 * we should remove the page from the page queues 698 * so we don't ever look at it again. 699 * adjust counters and such. 700 */ 701 702 p->flags |= PG_BUSY; 703 UVM_PAGE_OWN(p, "scan_inactive"); 704 705 p->flags |= PG_PAGEOUT; 706 uvmexp.paging++; 707 uvm_pagedequeue(p); 708 709 uvmexp.pgswapout++; 710 711 /* 712 * add the new page to the cluster. 713 */ 714 715 if (anon) { 716 anon->an_swslot = swslot + swcpages; 717 simple_unlock(slock); 718 } else { 719 result = uao_set_swslot(uobj, 720 p->offset >> PAGE_SHIFT, swslot + swcpages); 721 if (result == -1) { 722 p->flags &= ~(PG_BUSY|PG_PAGEOUT); 723 UVM_PAGE_OWN(p, NULL); 724 uvmexp.paging--; 725 uvm_pageactivate(p); 726 simple_unlock(slock); 727 continue; 728 } 729 simple_unlock(slock); 730 } 731 swpps[swcpages] = p; 732 swcpages++; 733 734 /* 735 * if the cluster isn't full, look for more pages 736 * before starting the i/o. 737 */ 738 739 if (swcpages < swnpages) { 740 continue; 741 } 742 #else /* defined(VMSWAP) */ 743 panic("%s: swap-backed", __func__); 744 #endif /* defined(VMSWAP) */ 745 746 } 747 748 #if defined(VMSWAP) 749 /* 750 * if this is the final pageout we could have a few 751 * unused swap blocks. if so, free them now. 752 */ 753 754 if (swcpages < swnpages) { 755 uvm_swap_free(swslot + swcpages, (swnpages - swcpages)); 756 } 757 758 /* 759 * now start the pageout. 760 */ 761 762 uvm_unlock_pageq(); 763 uvmexp.pdpageouts++; 764 error = uvm_swap_put(swslot, swpps, swcpages, 0); 765 KASSERT(error == 0); 766 uvm_lock_pageq(); 767 768 /* 769 * zero swslot to indicate that we are 770 * no longer building a swap-backed cluster. 771 */ 772 773 swslot = 0; 774 775 /* 776 * the pageout is in progress. bump counters and set up 777 * for the next loop. 778 */ 779 780 uvmexp.pdpending++; 781 if (nextpg && (nextpg->pqflags & PQ_INACTIVE) == 0) { 782 nextpg = TAILQ_FIRST(pglst); 783 } 784 #endif /* defined(VMSWAP) */ 785 } 786 } 787 788 /* 789 * uvmpd_scan: scan the page queues and attempt to meet our targets. 790 * 791 * => called with pageq's locked 792 */ 793 794 static void 795 uvmpd_scan(void) 796 { 797 int inactive_shortage, swap_shortage, pages_freed; 798 struct vm_page *p, *nextpg; 799 struct uvm_object *uobj; 800 struct vm_anon *anon; 801 struct simplelock *slock; 802 UVMHIST_FUNC("uvmpd_scan"); UVMHIST_CALLED(pdhist); 803 804 uvmexp.pdrevs++; 805 uobj = NULL; 806 anon = NULL; 807 808 #ifndef __SWAP_BROKEN 809 810 /* 811 * swap out some processes if we are below our free target. 812 * we need to unlock the page queues for this. 813 */ 814 815 if (uvmexp.free < uvmexp.freetarg && uvmexp.nswapdev != 0) { 816 uvmexp.pdswout++; 817 UVMHIST_LOG(pdhist," free %d < target %d: swapout", 818 uvmexp.free, uvmexp.freetarg, 0, 0); 819 uvm_unlock_pageq(); 820 uvm_swapout_threads(); 821 uvm_lock_pageq(); 822 823 } 824 #endif 825 826 /* 827 * now we want to work on meeting our targets. first we work on our 828 * free target by converting inactive pages into free pages. then 829 * we work on meeting our inactive target by converting active pages 830 * to inactive ones. 831 */ 832 833 UVMHIST_LOG(pdhist, " starting 'free' loop",0,0,0,0); 834 835 pages_freed = uvmexp.pdfreed; 836 uvmpd_scan_inactive(&uvm.page_inactive); 837 pages_freed = uvmexp.pdfreed - pages_freed; 838 839 /* 840 * we have done the scan to get free pages. now we work on meeting 841 * our inactive target. 842 */ 843 844 inactive_shortage = uvmexp.inactarg - uvmexp.inactive; 845 846 /* 847 * detect if we're not going to be able to page anything out 848 * until we free some swap resources from active pages. 849 */ 850 851 swap_shortage = 0; 852 if (uvmexp.free < uvmexp.freetarg && 853 uvmexp.swpginuse >= uvmexp.swpgavail && 854 !uvm_swapisfull() && 855 pages_freed == 0) { 856 swap_shortage = uvmexp.freetarg - uvmexp.free; 857 } 858 859 UVMHIST_LOG(pdhist, " loop 2: inactive_shortage=%d swap_shortage=%d", 860 inactive_shortage, swap_shortage,0,0); 861 for (p = TAILQ_FIRST(&uvm.page_active); 862 p != NULL && (inactive_shortage > 0 || swap_shortage > 0); 863 p = nextpg) { 864 nextpg = TAILQ_NEXT(p, pageq); 865 if (p->flags & PG_BUSY) { 866 continue; 867 } 868 869 /* 870 * lock the page's owner. 871 */ 872 873 if (p->uobject != NULL) { 874 uobj = p->uobject; 875 slock = &uobj->vmobjlock; 876 if (!simple_lock_try(slock)) { 877 continue; 878 } 879 } else { 880 anon = p->uanon; 881 KASSERT(anon != NULL); 882 slock = &anon->an_lock; 883 if (!simple_lock_try(slock)) { 884 continue; 885 } 886 887 /* take over the page? */ 888 if ((p->pqflags & PQ_ANON) == 0) { 889 KASSERT(p->loan_count > 0); 890 p->loan_count--; 891 p->pqflags |= PQ_ANON; 892 } 893 } 894 895 /* 896 * skip this page if it's busy. 897 */ 898 899 if ((p->flags & PG_BUSY) != 0) { 900 simple_unlock(slock); 901 continue; 902 } 903 904 #if defined(VMSWAP) 905 /* 906 * if there's a shortage of swap, free any swap allocated 907 * to this page so that other pages can be paged out. 908 */ 909 910 if (swap_shortage > 0) { 911 if ((p->pqflags & PQ_ANON) && anon->an_swslot) { 912 uvm_swap_free(anon->an_swslot, 1); 913 anon->an_swslot = 0; 914 p->flags &= ~PG_CLEAN; 915 swap_shortage--; 916 } else if (p->pqflags & PQ_AOBJ) { 917 int slot = uao_set_swslot(uobj, 918 p->offset >> PAGE_SHIFT, 0); 919 if (slot) { 920 uvm_swap_free(slot, 1); 921 p->flags &= ~PG_CLEAN; 922 swap_shortage--; 923 } 924 } 925 } 926 #endif /* defined(VMSWAP) */ 927 928 /* 929 * if there's a shortage of inactive pages, deactivate. 930 */ 931 932 if (inactive_shortage > 0) { 933 /* no need to check wire_count as pg is "active" */ 934 uvm_pagedeactivate(p); 935 uvmexp.pddeact++; 936 inactive_shortage--; 937 } 938 939 /* 940 * we're done with this page. 941 */ 942 943 simple_unlock(slock); 944 } 945 } 946 947 /* 948 * uvm_reclaimable: decide whether to wait for pagedaemon. 949 * 950 * => return TRUE if it seems to be worth to do uvm_wait. 951 * 952 * XXX should be tunable. 953 * XXX should consider pools, etc? 954 */ 955 956 boolean_t 957 uvm_reclaimable(void) 958 { 959 int filepages; 960 961 /* 962 * if swap is not full, no problem. 963 */ 964 965 if (!uvm_swapisfull()) { 966 return TRUE; 967 } 968 969 /* 970 * file-backed pages can be reclaimed even when swap is full. 971 * if we have more than 1/16 of pageable memory or 5MB, try to reclaim. 972 * 973 * XXX assume the worst case, ie. all wired pages are file-backed. 974 * 975 * XXX should consider about other reclaimable memory. 976 * XXX ie. pools, traditional buffer cache. 977 */ 978 979 filepages = uvmexp.filepages + uvmexp.execpages - uvmexp.wired; 980 if (filepages >= MIN((uvmexp.active + uvmexp.inactive) >> 4, 981 5 * 1024 * 1024 >> PAGE_SHIFT)) { 982 return TRUE; 983 } 984 985 /* 986 * kill the process, fail allocation, etc.. 987 */ 988 989 return FALSE; 990 } 991