1 /* $NetBSD: uvm_pdaemon.c,v 1.37 2001/09/15 20:36:47 chs 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 #include "opt_uvmhist.h" 70 71 /* 72 * uvm_pdaemon.c: the page daemon 73 */ 74 75 #include <sys/param.h> 76 #include <sys/proc.h> 77 #include <sys/systm.h> 78 #include <sys/kernel.h> 79 #include <sys/pool.h> 80 #include <sys/buf.h> 81 #include <sys/vnode.h> 82 83 #include <uvm/uvm.h> 84 85 /* 86 * UVMPD_NUMDIRTYREACTS is how many dirty pages the pagedeamon will reactivate 87 * in a pass thru the inactive list when swap is full. the value should be 88 * "small"... if it's too large we'll cycle the active pages thru the inactive 89 * queue too quickly to for them to be referenced and avoid being freed. 90 */ 91 92 #define UVMPD_NUMDIRTYREACTS 16 93 94 95 /* 96 * local prototypes 97 */ 98 99 void uvmpd_scan __P((void)); 100 boolean_t uvmpd_scan_inactive __P((struct pglist *)); 101 void uvmpd_tune __P((void)); 102 103 /* 104 * uvm_wait: wait (sleep) for the page daemon to free some pages 105 * 106 * => should be called with all locks released 107 * => should _not_ be called by the page daemon (to avoid deadlock) 108 */ 109 110 void 111 uvm_wait(wmsg) 112 const char *wmsg; 113 { 114 int timo = 0; 115 int s = splbio(); 116 117 /* 118 * check for page daemon going to sleep (waiting for itself) 119 */ 120 121 if (curproc == uvm.pagedaemon_proc && uvmexp.paging == 0) { 122 /* 123 * now we have a problem: the pagedaemon wants to go to 124 * sleep until it frees more memory. but how can it 125 * free more memory if it is asleep? that is a deadlock. 126 * we have two options: 127 * [1] panic now 128 * [2] put a timeout on the sleep, thus causing the 129 * pagedaemon to only pause (rather than sleep forever) 130 * 131 * note that option [2] will only help us if we get lucky 132 * and some other process on the system breaks the deadlock 133 * by exiting or freeing memory (thus allowing the pagedaemon 134 * to continue). for now we panic if DEBUG is defined, 135 * otherwise we hope for the best with option [2] (better 136 * yet, this should never happen in the first place!). 137 */ 138 139 printf("pagedaemon: deadlock detected!\n"); 140 timo = hz >> 3; /* set timeout */ 141 #if defined(DEBUG) 142 /* DEBUG: panic so we can debug it */ 143 panic("pagedaemon deadlock"); 144 #endif 145 } 146 147 simple_lock(&uvm.pagedaemon_lock); 148 wakeup(&uvm.pagedaemon); /* wake the daemon! */ 149 UVM_UNLOCK_AND_WAIT(&uvmexp.free, &uvm.pagedaemon_lock, FALSE, wmsg, 150 timo); 151 152 splx(s); 153 } 154 155 156 /* 157 * uvmpd_tune: tune paging parameters 158 * 159 * => called when ever memory is added (or removed?) to the system 160 * => caller must call with page queues locked 161 */ 162 163 void 164 uvmpd_tune(void) 165 { 166 UVMHIST_FUNC("uvmpd_tune"); UVMHIST_CALLED(pdhist); 167 168 uvmexp.freemin = uvmexp.npages / 20; 169 170 /* between 16k and 256k */ 171 /* XXX: what are these values good for? */ 172 uvmexp.freemin = MAX(uvmexp.freemin, (16*1024) >> PAGE_SHIFT); 173 uvmexp.freemin = MIN(uvmexp.freemin, (256*1024) >> PAGE_SHIFT); 174 175 /* Make sure there's always a user page free. */ 176 if (uvmexp.freemin < uvmexp.reserve_kernel + 1) 177 uvmexp.freemin = uvmexp.reserve_kernel + 1; 178 179 uvmexp.freetarg = (uvmexp.freemin * 4) / 3; 180 if (uvmexp.freetarg <= uvmexp.freemin) 181 uvmexp.freetarg = uvmexp.freemin + 1; 182 183 /* uvmexp.inactarg: computed in main daemon loop */ 184 185 uvmexp.wiredmax = uvmexp.npages / 3; 186 UVMHIST_LOG(pdhist, "<- done, freemin=%d, freetarg=%d, wiredmax=%d", 187 uvmexp.freemin, uvmexp.freetarg, uvmexp.wiredmax, 0); 188 } 189 190 /* 191 * uvm_pageout: the main loop for the pagedaemon 192 */ 193 194 void 195 uvm_pageout(void *arg) 196 { 197 int npages = 0; 198 UVMHIST_FUNC("uvm_pageout"); UVMHIST_CALLED(pdhist); 199 200 UVMHIST_LOG(pdhist,"<starting uvm pagedaemon>", 0, 0, 0, 0); 201 202 /* 203 * ensure correct priority and set paging parameters... 204 */ 205 206 uvm.pagedaemon_proc = curproc; 207 uvm_lock_pageq(); 208 npages = uvmexp.npages; 209 uvmpd_tune(); 210 uvm_unlock_pageq(); 211 212 /* 213 * main loop 214 */ 215 216 for (;;) { 217 simple_lock(&uvm.pagedaemon_lock); 218 219 UVMHIST_LOG(pdhist," <<SLEEPING>>",0,0,0,0); 220 UVM_UNLOCK_AND_WAIT(&uvm.pagedaemon, 221 &uvm.pagedaemon_lock, FALSE, "pgdaemon", 0); 222 uvmexp.pdwoke++; 223 UVMHIST_LOG(pdhist," <<WOKE UP>>",0,0,0,0); 224 225 /* drain pool resources */ 226 pool_drain(0); 227 228 /* 229 * now lock page queues and recompute inactive count 230 */ 231 232 uvm_lock_pageq(); 233 if (npages != uvmexp.npages) { /* check for new pages? */ 234 npages = uvmexp.npages; 235 uvmpd_tune(); 236 } 237 238 uvmexp.inactarg = (uvmexp.active + uvmexp.inactive) / 3; 239 if (uvmexp.inactarg <= uvmexp.freetarg) { 240 uvmexp.inactarg = uvmexp.freetarg + 1; 241 } 242 243 UVMHIST_LOG(pdhist," free/ftarg=%d/%d, inact/itarg=%d/%d", 244 uvmexp.free, uvmexp.freetarg, uvmexp.inactive, 245 uvmexp.inactarg); 246 247 /* 248 * scan if needed 249 */ 250 251 if (uvmexp.free + uvmexp.paging < uvmexp.freetarg || 252 uvmexp.inactive < uvmexp.inactarg) { 253 uvmpd_scan(); 254 } 255 256 /* 257 * if there's any free memory to be had, 258 * wake up any waiters. 259 */ 260 261 if (uvmexp.free > uvmexp.reserve_kernel || 262 uvmexp.paging == 0) { 263 wakeup(&uvmexp.free); 264 } 265 266 /* 267 * scan done. unlock page queues (the only lock we are holding) 268 */ 269 270 uvm_unlock_pageq(); 271 } 272 /*NOTREACHED*/ 273 } 274 275 276 /* 277 * uvm_aiodone_daemon: main loop for the aiodone daemon. 278 */ 279 280 void 281 uvm_aiodone_daemon(void *arg) 282 { 283 int s, free; 284 struct buf *bp, *nbp; 285 UVMHIST_FUNC("uvm_aiodoned"); UVMHIST_CALLED(pdhist); 286 287 for (;;) { 288 289 /* 290 * carefully attempt to go to sleep (without losing "wakeups"!). 291 * we need splbio because we want to make sure the aio_done list 292 * is totally empty before we go to sleep. 293 */ 294 295 s = splbio(); 296 simple_lock(&uvm.aiodoned_lock); 297 if (TAILQ_FIRST(&uvm.aio_done) == NULL) { 298 UVMHIST_LOG(pdhist," <<SLEEPING>>",0,0,0,0); 299 UVM_UNLOCK_AND_WAIT(&uvm.aiodoned, 300 &uvm.aiodoned_lock, FALSE, "aiodoned", 0); 301 UVMHIST_LOG(pdhist," <<WOKE UP>>",0,0,0,0); 302 303 /* relock aiodoned_lock, still at splbio */ 304 simple_lock(&uvm.aiodoned_lock); 305 } 306 307 /* 308 * check for done aio structures 309 */ 310 311 bp = TAILQ_FIRST(&uvm.aio_done); 312 if (bp) { 313 TAILQ_INIT(&uvm.aio_done); 314 } 315 316 simple_unlock(&uvm.aiodoned_lock); 317 splx(s); 318 319 /* 320 * process each i/o that's done. 321 */ 322 323 free = uvmexp.free; 324 while (bp != NULL) { 325 nbp = TAILQ_NEXT(bp, b_freelist); 326 (*bp->b_iodone)(bp); 327 bp = nbp; 328 } 329 if (free <= uvmexp.reserve_kernel) { 330 s = uvm_lock_fpageq(); 331 wakeup(&uvm.pagedaemon); 332 uvm_unlock_fpageq(s); 333 } else { 334 simple_lock(&uvm.pagedaemon_lock); 335 wakeup(&uvmexp.free); 336 simple_unlock(&uvm.pagedaemon_lock); 337 } 338 } 339 } 340 341 /* 342 * uvmpd_scan_inactive: scan an inactive list for pages to clean or free. 343 * 344 * => called with page queues locked 345 * => we work on meeting our free target by converting inactive pages 346 * into free pages. 347 * => we handle the building of swap-backed clusters 348 * => we return TRUE if we are exiting because we met our target 349 */ 350 351 boolean_t 352 uvmpd_scan_inactive(pglst) 353 struct pglist *pglst; 354 { 355 boolean_t retval = FALSE; /* assume we haven't hit target */ 356 int error; 357 struct vm_page *p, *nextpg; 358 struct uvm_object *uobj; 359 struct vm_anon *anon; 360 struct vm_page *swpps[MAXBSIZE >> PAGE_SHIFT]; 361 struct simplelock *slock; 362 int swnpages, swcpages; 363 int swslot; 364 int dirtyreacts, t, result; 365 UVMHIST_FUNC("uvmpd_scan_inactive"); UVMHIST_CALLED(pdhist); 366 367 /* 368 * swslot is non-zero if we are building a swap cluster. we want 369 * to stay in the loop while we have a page to scan or we have 370 * a swap-cluster to build. 371 */ 372 373 swslot = 0; 374 swnpages = swcpages = 0; 375 dirtyreacts = 0; 376 for (p = TAILQ_FIRST(pglst); p != NULL || swslot != 0; p = nextpg) { 377 uobj = NULL; 378 anon = NULL; 379 if (p) { 380 381 /* 382 * see if we've met the free target. 383 */ 384 385 if (uvmexp.free + uvmexp.paging >= 386 uvmexp.freetarg << 2 || 387 dirtyreacts == UVMPD_NUMDIRTYREACTS) { 388 UVMHIST_LOG(pdhist," met free target: " 389 "exit loop", 0, 0, 0, 0); 390 retval = TRUE; 391 392 if (swslot == 0) { 393 /* exit now if no swap-i/o pending */ 394 break; 395 } 396 397 /* set p to null to signal final swap i/o */ 398 p = NULL; 399 nextpg = NULL; 400 } 401 } 402 if (p) { /* if (we have a new page to consider) */ 403 404 /* 405 * we are below target and have a new page to consider. 406 */ 407 408 uvmexp.pdscans++; 409 nextpg = TAILQ_NEXT(p, pageq); 410 411 /* 412 * move referenced pages back to active queue and 413 * skip to next page. 414 */ 415 416 if (pmap_clear_reference(p)) { 417 uvm_pageactivate(p); 418 uvmexp.pdreact++; 419 continue; 420 } 421 anon = p->uanon; 422 uobj = p->uobject; 423 424 /* 425 * enforce the minimum thresholds on different 426 * types of memory usage. if reusing the current 427 * page would reduce that type of usage below its 428 * minimum, reactivate the page instead and move 429 * on to the next page. 430 */ 431 432 t = uvmexp.active + uvmexp.inactive + uvmexp.free; 433 if (anon && 434 uvmexp.anonpages <= (t * uvmexp.anonmin) >> 8) { 435 uvm_pageactivate(p); 436 uvmexp.pdreanon++; 437 continue; 438 } 439 if (uobj && UVM_OBJ_IS_VTEXT(uobj) && 440 uvmexp.vtextpages <= (t * uvmexp.vtextmin) >> 8) { 441 uvm_pageactivate(p); 442 uvmexp.pdrevtext++; 443 continue; 444 } 445 if (uobj && UVM_OBJ_IS_VNODE(uobj) && 446 !UVM_OBJ_IS_VTEXT(uobj) && 447 uvmexp.vnodepages <= (t * uvmexp.vnodemin) >> 8) { 448 uvm_pageactivate(p); 449 uvmexp.pdrevnode++; 450 continue; 451 } 452 453 /* 454 * first we attempt to lock the object that this page 455 * belongs to. if our attempt fails we skip on to 456 * the next page (no harm done). it is important to 457 * "try" locking the object as we are locking in the 458 * wrong order (pageq -> object) and we don't want to 459 * deadlock. 460 * 461 * the only time we expect to see an ownerless page 462 * (i.e. a page with no uobject and !PQ_ANON) is if an 463 * anon has loaned a page from a uvm_object and the 464 * uvm_object has dropped the ownership. in that 465 * case, the anon can "take over" the loaned page 466 * and make it its own. 467 */ 468 469 /* is page part of an anon or ownerless ? */ 470 if ((p->pqflags & PQ_ANON) || uobj == NULL) { 471 KASSERT(anon != NULL); 472 slock = &anon->an_lock; 473 if (!simple_lock_try(slock)) { 474 /* lock failed, skip this page */ 475 continue; 476 } 477 478 /* 479 * if the page is ownerless, claim it in the 480 * name of "anon"! 481 */ 482 483 if ((p->pqflags & PQ_ANON) == 0) { 484 KASSERT(p->loan_count > 0); 485 p->loan_count--; 486 p->pqflags |= PQ_ANON; 487 /* anon now owns it */ 488 } 489 if (p->flags & PG_BUSY) { 490 simple_unlock(slock); 491 uvmexp.pdbusy++; 492 continue; 493 } 494 uvmexp.pdanscan++; 495 } else { 496 KASSERT(uobj != NULL); 497 slock = &uobj->vmobjlock; 498 if (!simple_lock_try(slock)) { 499 continue; 500 } 501 if (p->flags & PG_BUSY) { 502 simple_unlock(slock); 503 uvmexp.pdbusy++; 504 continue; 505 } 506 uvmexp.pdobscan++; 507 } 508 509 510 /* 511 * we now have the object and the page queues locked. 512 * if the page is not swap-backed, call the object's 513 * pager to flush and free the page. 514 */ 515 516 if ((p->pqflags & PQ_SWAPBACKED) == 0) { 517 uvm_unlock_pageq(); 518 error = (uobj->pgops->pgo_put)(uobj, p->offset, 519 p->offset + PAGE_SIZE, 520 PGO_CLEANIT|PGO_FREE); 521 uvm_lock_pageq(); 522 if (nextpg && 523 (nextpg->flags & PQ_INACTIVE) == 0) { 524 nextpg = TAILQ_FIRST(pglst); 525 } 526 continue; 527 } 528 529 /* 530 * the page is swap-backed. remove all the permissions 531 * from the page so we can sync the modified info 532 * without any race conditions. if the page is clean 533 * we can free it now and continue. 534 */ 535 536 pmap_page_protect(p, VM_PROT_NONE); 537 if ((p->flags & PG_CLEAN) && pmap_clear_modify(p)) { 538 p->flags &= ~(PG_CLEAN); 539 } 540 if (p->flags & PG_CLEAN) { 541 uvm_pagefree(p); 542 uvmexp.pdfreed++; 543 544 /* 545 * for anons, we need to remove the page 546 * from the anon ourselves. for aobjs, 547 * pagefree did that for us. 548 */ 549 550 if (anon) { 551 KASSERT(anon->an_swslot != 0); 552 anon->u.an_page = NULL; 553 } 554 simple_unlock(slock); 555 continue; 556 } 557 558 /* 559 * this page is dirty, skip it if we'll have met our 560 * free target when all the current pageouts complete. 561 */ 562 563 if (uvmexp.free + uvmexp.paging > 564 uvmexp.freetarg << 2) { 565 simple_unlock(slock); 566 continue; 567 } 568 569 /* 570 * free any swap space allocated to the page since 571 * we'll have to write it again with its new data. 572 */ 573 574 if ((p->pqflags & PQ_ANON) && anon->an_swslot) { 575 uvm_swap_free(anon->an_swslot, 1); 576 anon->an_swslot = 0; 577 } else if (p->pqflags & PQ_AOBJ) { 578 uao_dropswap(uobj, p->offset >> PAGE_SHIFT); 579 } 580 581 /* 582 * if all pages in swap are only in swap, 583 * the swap space is full and we can't page out 584 * any more swap-backed pages. reactivate this page 585 * so that we eventually cycle all pages through 586 * the inactive queue. 587 */ 588 589 KASSERT(uvmexp.swpgonly <= uvmexp.swpages); 590 if (uvmexp.swpgonly == uvmexp.swpages) { 591 dirtyreacts++; 592 uvm_pageactivate(p); 593 simple_unlock(slock); 594 continue; 595 } 596 597 /* 598 * start new swap pageout cluster (if necessary). 599 */ 600 601 if (swslot == 0) { 602 swnpages = MAXBSIZE >> PAGE_SHIFT; 603 swslot = uvm_swap_alloc(&swnpages, TRUE); 604 if (swslot == 0) { 605 simple_unlock(slock); 606 continue; 607 } 608 swcpages = 0; 609 } 610 611 /* 612 * at this point, we're definitely going reuse this 613 * page. mark the page busy and delayed-free. 614 * we should remove the page from the page queues 615 * so we don't ever look at it again. 616 * adjust counters and such. 617 */ 618 619 p->flags |= PG_BUSY; 620 UVM_PAGE_OWN(p, "scan_inactive"); 621 622 p->flags |= PG_PAGEOUT; 623 uvmexp.paging++; 624 uvm_pagedequeue(p); 625 626 uvmexp.pgswapout++; 627 628 /* 629 * add the new page to the cluster. 630 */ 631 632 if (anon) { 633 anon->an_swslot = swslot + swcpages; 634 simple_unlock(slock); 635 } else { 636 result = uao_set_swslot(uobj, 637 p->offset >> PAGE_SHIFT, swslot + swcpages); 638 if (result == -1) { 639 p->flags &= ~(PG_BUSY|PG_PAGEOUT); 640 UVM_PAGE_OWN(p, NULL); 641 uvmexp.paging--; 642 uvm_pageactivate(p); 643 simple_unlock(slock); 644 continue; 645 } 646 simple_unlock(slock); 647 } 648 swpps[swcpages] = p; 649 swcpages++; 650 651 /* 652 * if the cluster isn't full, look for more pages 653 * before starting the i/o. 654 */ 655 656 if (swcpages < swnpages) { 657 continue; 658 } 659 } 660 661 /* 662 * if this is the final pageout we could have a few 663 * unused swap blocks. if so, free them now. 664 */ 665 666 if (swcpages < swnpages) { 667 uvm_swap_free(swslot + swcpages, (swnpages - swcpages)); 668 } 669 670 /* 671 * now start the pageout. 672 */ 673 674 uvm_unlock_pageq(); 675 uvmexp.pdpageouts++; 676 error = uvm_swap_put(swslot, swpps, swcpages, 0); 677 KASSERT(error == 0); 678 uvm_lock_pageq(); 679 680 /* 681 * zero swslot to indicate that we are 682 * no longer building a swap-backed cluster. 683 */ 684 685 swslot = 0; 686 687 /* 688 * the pageout is in progress. bump counters and set up 689 * for the next loop. 690 */ 691 692 uvmexp.pdpending++; 693 if (nextpg && (nextpg->pqflags & PQ_INACTIVE) == 0) { 694 nextpg = TAILQ_FIRST(pglst); 695 } 696 } 697 return (error); 698 } 699 700 /* 701 * uvmpd_scan: scan the page queues and attempt to meet our targets. 702 * 703 * => called with pageq's locked 704 */ 705 706 void 707 uvmpd_scan(void) 708 { 709 int inactive_shortage, swap_shortage, pages_freed; 710 struct vm_page *p, *nextpg; 711 struct uvm_object *uobj; 712 struct vm_anon *anon; 713 boolean_t got_it; 714 UVMHIST_FUNC("uvmpd_scan"); UVMHIST_CALLED(pdhist); 715 716 uvmexp.pdrevs++; 717 uobj = NULL; 718 anon = NULL; 719 720 #ifndef __SWAP_BROKEN 721 /* 722 * swap out some processes if we are below our free target. 723 * we need to unlock the page queues for this. 724 */ 725 if (uvmexp.free < uvmexp.freetarg) { 726 uvmexp.pdswout++; 727 UVMHIST_LOG(pdhist," free %d < target %d: swapout", 728 uvmexp.free, uvmexp.freetarg, 0, 0); 729 uvm_unlock_pageq(); 730 uvm_swapout_threads(); 731 uvm_lock_pageq(); 732 733 } 734 #endif 735 736 /* 737 * now we want to work on meeting our targets. first we work on our 738 * free target by converting inactive pages into free pages. then 739 * we work on meeting our inactive target by converting active pages 740 * to inactive ones. 741 */ 742 743 UVMHIST_LOG(pdhist, " starting 'free' loop",0,0,0,0); 744 745 /* 746 * alternate starting queue between swap and object based on the 747 * low bit of uvmexp.pdrevs (which we bump by one each call). 748 */ 749 750 got_it = FALSE; 751 pages_freed = uvmexp.pdfreed; 752 (void) uvmpd_scan_inactive(&uvm.page_inactive); 753 pages_freed = uvmexp.pdfreed - pages_freed; 754 755 /* 756 * we have done the scan to get free pages. now we work on meeting 757 * our inactive target. 758 */ 759 760 inactive_shortage = uvmexp.inactarg - uvmexp.inactive; 761 762 /* 763 * detect if we're not going to be able to page anything out 764 * until we free some swap resources from active pages. 765 */ 766 767 swap_shortage = 0; 768 if (uvmexp.free < uvmexp.freetarg && 769 uvmexp.swpginuse == uvmexp.swpages && 770 uvmexp.swpgonly < uvmexp.swpages && 771 pages_freed == 0) { 772 swap_shortage = uvmexp.freetarg - uvmexp.free; 773 } 774 775 UVMHIST_LOG(pdhist, " loop 2: inactive_shortage=%d swap_shortage=%d", 776 inactive_shortage, swap_shortage,0,0); 777 for (p = TAILQ_FIRST(&uvm.page_active); 778 p != NULL && (inactive_shortage > 0 || swap_shortage > 0); 779 p = nextpg) { 780 nextpg = TAILQ_NEXT(p, pageq); 781 if (p->flags & PG_BUSY) { 782 continue; 783 } 784 785 /* 786 * lock the page's owner. 787 */ 788 /* is page anon owned or ownerless? */ 789 if ((p->pqflags & PQ_ANON) || p->uobject == NULL) { 790 anon = p->uanon; 791 KASSERT(anon != NULL); 792 if (!simple_lock_try(&anon->an_lock)) { 793 continue; 794 } 795 796 /* take over the page? */ 797 if ((p->pqflags & PQ_ANON) == 0) { 798 KASSERT(p->loan_count > 0); 799 p->loan_count--; 800 p->pqflags |= PQ_ANON; 801 } 802 } else { 803 uobj = p->uobject; 804 if (!simple_lock_try(&uobj->vmobjlock)) { 805 continue; 806 } 807 } 808 809 /* 810 * skip this page if it's busy. 811 */ 812 813 if ((p->flags & PG_BUSY) != 0) { 814 if (p->pqflags & PQ_ANON) 815 simple_unlock(&anon->an_lock); 816 else 817 simple_unlock(&uobj->vmobjlock); 818 continue; 819 } 820 821 /* 822 * if there's a shortage of swap, free any swap allocated 823 * to this page so that other pages can be paged out. 824 */ 825 826 if (swap_shortage > 0) { 827 if ((p->pqflags & PQ_ANON) && anon->an_swslot) { 828 uvm_swap_free(anon->an_swslot, 1); 829 anon->an_swslot = 0; 830 p->flags &= ~PG_CLEAN; 831 swap_shortage--; 832 } else if (p->pqflags & PQ_AOBJ) { 833 int slot = uao_set_swslot(uobj, 834 p->offset >> PAGE_SHIFT, 0); 835 if (slot) { 836 uvm_swap_free(slot, 1); 837 p->flags &= ~PG_CLEAN; 838 swap_shortage--; 839 } 840 } 841 } 842 843 /* 844 * if there's a shortage of inactive pages, deactivate. 845 */ 846 847 if (inactive_shortage > 0) { 848 /* no need to check wire_count as pg is "active" */ 849 uvm_pagedeactivate(p); 850 uvmexp.pddeact++; 851 inactive_shortage--; 852 } 853 854 /* 855 * we're done with this page. 856 */ 857 858 if (p->pqflags & PQ_ANON) 859 simple_unlock(&anon->an_lock); 860 else 861 simple_unlock(&uobj->vmobjlock); 862 } 863 } 864