1 /* $NetBSD: uvm_pdaemon.c,v 1.39 2001/09/30 02:57:34 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 /* 226 * now lock page queues and recompute inactive count 227 */ 228 229 uvm_lock_pageq(); 230 if (npages != uvmexp.npages) { /* check for new pages? */ 231 npages = uvmexp.npages; 232 uvmpd_tune(); 233 } 234 235 uvmexp.inactarg = (uvmexp.active + uvmexp.inactive) / 3; 236 if (uvmexp.inactarg <= uvmexp.freetarg) { 237 uvmexp.inactarg = uvmexp.freetarg + 1; 238 } 239 240 UVMHIST_LOG(pdhist," free/ftarg=%d/%d, inact/itarg=%d/%d", 241 uvmexp.free, uvmexp.freetarg, uvmexp.inactive, 242 uvmexp.inactarg); 243 244 /* 245 * scan if needed 246 */ 247 248 if (uvmexp.free + uvmexp.paging < uvmexp.freetarg || 249 uvmexp.inactive < uvmexp.inactarg) { 250 uvmpd_scan(); 251 } 252 253 /* 254 * if there's any free memory to be had, 255 * wake up any waiters. 256 */ 257 258 if (uvmexp.free > uvmexp.reserve_kernel || 259 uvmexp.paging == 0) { 260 wakeup(&uvmexp.free); 261 } 262 263 /* 264 * scan done. unlock page queues (the only lock we are holding) 265 */ 266 267 uvm_unlock_pageq(); 268 269 /* 270 * drain pool resources now that we're not holding any locks 271 */ 272 273 pool_drain(0); 274 } 275 /*NOTREACHED*/ 276 } 277 278 279 /* 280 * uvm_aiodone_daemon: main loop for the aiodone daemon. 281 */ 282 283 void 284 uvm_aiodone_daemon(void *arg) 285 { 286 int s, free; 287 struct buf *bp, *nbp; 288 UVMHIST_FUNC("uvm_aiodoned"); UVMHIST_CALLED(pdhist); 289 290 for (;;) { 291 292 /* 293 * carefully attempt to go to sleep (without losing "wakeups"!). 294 * we need splbio because we want to make sure the aio_done list 295 * is totally empty before we go to sleep. 296 */ 297 298 s = splbio(); 299 simple_lock(&uvm.aiodoned_lock); 300 if (TAILQ_FIRST(&uvm.aio_done) == NULL) { 301 UVMHIST_LOG(pdhist," <<SLEEPING>>",0,0,0,0); 302 UVM_UNLOCK_AND_WAIT(&uvm.aiodoned, 303 &uvm.aiodoned_lock, FALSE, "aiodoned", 0); 304 UVMHIST_LOG(pdhist," <<WOKE UP>>",0,0,0,0); 305 306 /* relock aiodoned_lock, still at splbio */ 307 simple_lock(&uvm.aiodoned_lock); 308 } 309 310 /* 311 * check for done aio structures 312 */ 313 314 bp = TAILQ_FIRST(&uvm.aio_done); 315 if (bp) { 316 TAILQ_INIT(&uvm.aio_done); 317 } 318 319 simple_unlock(&uvm.aiodoned_lock); 320 splx(s); 321 322 /* 323 * process each i/o that's done. 324 */ 325 326 free = uvmexp.free; 327 while (bp != NULL) { 328 nbp = TAILQ_NEXT(bp, b_freelist); 329 (*bp->b_iodone)(bp); 330 bp = nbp; 331 } 332 if (free <= uvmexp.reserve_kernel) { 333 s = uvm_lock_fpageq(); 334 wakeup(&uvm.pagedaemon); 335 uvm_unlock_fpageq(s); 336 } else { 337 simple_lock(&uvm.pagedaemon_lock); 338 wakeup(&uvmexp.free); 339 simple_unlock(&uvm.pagedaemon_lock); 340 } 341 } 342 } 343 344 /* 345 * uvmpd_scan_inactive: scan an inactive list for pages to clean or free. 346 * 347 * => called with page queues locked 348 * => we work on meeting our free target by converting inactive pages 349 * into free pages. 350 * => we handle the building of swap-backed clusters 351 * => we return TRUE if we are exiting because we met our target 352 */ 353 354 boolean_t 355 uvmpd_scan_inactive(pglst) 356 struct pglist *pglst; 357 { 358 boolean_t retval = FALSE; /* assume we haven't hit target */ 359 int error; 360 struct vm_page *p, *nextpg; 361 struct uvm_object *uobj; 362 struct vm_anon *anon; 363 struct vm_page *swpps[MAXBSIZE >> PAGE_SHIFT]; 364 struct simplelock *slock; 365 int swnpages, swcpages; 366 int swslot; 367 int dirtyreacts, t, result; 368 UVMHIST_FUNC("uvmpd_scan_inactive"); UVMHIST_CALLED(pdhist); 369 370 /* 371 * swslot is non-zero if we are building a swap cluster. we want 372 * to stay in the loop while we have a page to scan or we have 373 * a swap-cluster to build. 374 */ 375 376 swslot = 0; 377 swnpages = swcpages = 0; 378 dirtyreacts = 0; 379 for (p = TAILQ_FIRST(pglst); p != NULL || swslot != 0; p = nextpg) { 380 uobj = NULL; 381 anon = NULL; 382 if (p) { 383 384 /* 385 * see if we've met the free target. 386 */ 387 388 if (uvmexp.free + uvmexp.paging >= 389 uvmexp.freetarg << 2 || 390 dirtyreacts == UVMPD_NUMDIRTYREACTS) { 391 UVMHIST_LOG(pdhist," met free target: " 392 "exit loop", 0, 0, 0, 0); 393 retval = TRUE; 394 395 if (swslot == 0) { 396 /* exit now if no swap-i/o pending */ 397 break; 398 } 399 400 /* set p to null to signal final swap i/o */ 401 p = NULL; 402 nextpg = NULL; 403 } 404 } 405 if (p) { /* if (we have a new page to consider) */ 406 407 /* 408 * we are below target and have a new page to consider. 409 */ 410 411 uvmexp.pdscans++; 412 nextpg = TAILQ_NEXT(p, pageq); 413 414 /* 415 * move referenced pages back to active queue and 416 * skip to next page. 417 */ 418 419 if (pmap_clear_reference(p)) { 420 uvm_pageactivate(p); 421 uvmexp.pdreact++; 422 continue; 423 } 424 anon = p->uanon; 425 uobj = p->uobject; 426 427 /* 428 * enforce the minimum thresholds on different 429 * types of memory usage. if reusing the current 430 * page would reduce that type of usage below its 431 * minimum, reactivate the page instead and move 432 * on to the next page. 433 */ 434 435 t = uvmexp.active + uvmexp.inactive + uvmexp.free; 436 if (anon && 437 uvmexp.anonpages <= (t * uvmexp.anonmin) >> 8) { 438 uvm_pageactivate(p); 439 uvmexp.pdreanon++; 440 continue; 441 } 442 if (uobj && UVM_OBJ_IS_VTEXT(uobj) && 443 uvmexp.vtextpages <= (t * uvmexp.vtextmin) >> 8) { 444 uvm_pageactivate(p); 445 uvmexp.pdrevtext++; 446 continue; 447 } 448 if (uobj && UVM_OBJ_IS_VNODE(uobj) && 449 !UVM_OBJ_IS_VTEXT(uobj) && 450 uvmexp.vnodepages <= (t * uvmexp.vnodemin) >> 8) { 451 uvm_pageactivate(p); 452 uvmexp.pdrevnode++; 453 continue; 454 } 455 456 /* 457 * first we attempt to lock the object that this page 458 * belongs to. if our attempt fails we skip on to 459 * the next page (no harm done). it is important to 460 * "try" locking the object as we are locking in the 461 * wrong order (pageq -> object) and we don't want to 462 * deadlock. 463 * 464 * the only time we expect to see an ownerless page 465 * (i.e. a page with no uobject and !PQ_ANON) is if an 466 * anon has loaned a page from a uvm_object and the 467 * uvm_object has dropped the ownership. in that 468 * case, the anon can "take over" the loaned page 469 * and make it its own. 470 */ 471 472 /* is page part of an anon or ownerless ? */ 473 if ((p->pqflags & PQ_ANON) || uobj == NULL) { 474 KASSERT(anon != NULL); 475 slock = &anon->an_lock; 476 if (!simple_lock_try(slock)) { 477 /* lock failed, skip this page */ 478 continue; 479 } 480 481 /* 482 * if the page is ownerless, claim it in the 483 * name of "anon"! 484 */ 485 486 if ((p->pqflags & PQ_ANON) == 0) { 487 KASSERT(p->loan_count > 0); 488 p->loan_count--; 489 p->pqflags |= PQ_ANON; 490 /* anon now owns it */ 491 } 492 if (p->flags & PG_BUSY) { 493 simple_unlock(slock); 494 uvmexp.pdbusy++; 495 continue; 496 } 497 uvmexp.pdanscan++; 498 } else { 499 KASSERT(uobj != NULL); 500 slock = &uobj->vmobjlock; 501 if (!simple_lock_try(slock)) { 502 continue; 503 } 504 if (p->flags & PG_BUSY) { 505 simple_unlock(slock); 506 uvmexp.pdbusy++; 507 continue; 508 } 509 uvmexp.pdobscan++; 510 } 511 512 513 /* 514 * we now have the object and the page queues locked. 515 * if the page is not swap-backed, call the object's 516 * pager to flush and free the page. 517 */ 518 519 if ((p->pqflags & PQ_SWAPBACKED) == 0) { 520 uvm_unlock_pageq(); 521 error = (uobj->pgops->pgo_put)(uobj, p->offset, 522 p->offset + PAGE_SIZE, 523 PGO_CLEANIT|PGO_FREE); 524 uvm_lock_pageq(); 525 if (nextpg && 526 (nextpg->flags & PQ_INACTIVE) == 0) { 527 nextpg = TAILQ_FIRST(pglst); 528 } 529 continue; 530 } 531 532 /* 533 * the page is swap-backed. remove all the permissions 534 * from the page so we can sync the modified info 535 * without any race conditions. if the page is clean 536 * we can free it now and continue. 537 */ 538 539 pmap_page_protect(p, VM_PROT_NONE); 540 if ((p->flags & PG_CLEAN) && pmap_clear_modify(p)) { 541 p->flags &= ~(PG_CLEAN); 542 } 543 if (p->flags & PG_CLEAN) { 544 uvm_pagefree(p); 545 uvmexp.pdfreed++; 546 547 /* 548 * for anons, we need to remove the page 549 * from the anon ourselves. for aobjs, 550 * pagefree did that for us. 551 */ 552 553 if (anon) { 554 KASSERT(anon->an_swslot != 0); 555 anon->u.an_page = NULL; 556 } 557 simple_unlock(slock); 558 continue; 559 } 560 561 /* 562 * this page is dirty, skip it if we'll have met our 563 * free target when all the current pageouts complete. 564 */ 565 566 if (uvmexp.free + uvmexp.paging > 567 uvmexp.freetarg << 2) { 568 simple_unlock(slock); 569 continue; 570 } 571 572 /* 573 * free any swap space allocated to the page since 574 * we'll have to write it again with its new data. 575 */ 576 577 if ((p->pqflags & PQ_ANON) && anon->an_swslot) { 578 uvm_swap_free(anon->an_swslot, 1); 579 anon->an_swslot = 0; 580 } else if (p->pqflags & PQ_AOBJ) { 581 uao_dropswap(uobj, p->offset >> PAGE_SHIFT); 582 } 583 584 /* 585 * if all pages in swap are only in swap, 586 * the swap space is full and we can't page out 587 * any more swap-backed pages. reactivate this page 588 * so that we eventually cycle all pages through 589 * the inactive queue. 590 */ 591 592 KASSERT(uvmexp.swpgonly <= uvmexp.swpages); 593 if (uvmexp.swpgonly == uvmexp.swpages) { 594 dirtyreacts++; 595 uvm_pageactivate(p); 596 simple_unlock(slock); 597 continue; 598 } 599 600 /* 601 * start new swap pageout cluster (if necessary). 602 */ 603 604 if (swslot == 0) { 605 swnpages = MAXBSIZE >> PAGE_SHIFT; 606 swslot = uvm_swap_alloc(&swnpages, TRUE); 607 if (swslot == 0) { 608 simple_unlock(slock); 609 continue; 610 } 611 swcpages = 0; 612 } 613 614 /* 615 * at this point, we're definitely going reuse this 616 * page. mark the page busy and delayed-free. 617 * we should remove the page from the page queues 618 * so we don't ever look at it again. 619 * adjust counters and such. 620 */ 621 622 p->flags |= PG_BUSY; 623 UVM_PAGE_OWN(p, "scan_inactive"); 624 625 p->flags |= PG_PAGEOUT; 626 uvmexp.paging++; 627 uvm_pagedequeue(p); 628 629 uvmexp.pgswapout++; 630 631 /* 632 * add the new page to the cluster. 633 */ 634 635 if (anon) { 636 anon->an_swslot = swslot + swcpages; 637 simple_unlock(slock); 638 } else { 639 result = uao_set_swslot(uobj, 640 p->offset >> PAGE_SHIFT, swslot + swcpages); 641 if (result == -1) { 642 p->flags &= ~(PG_BUSY|PG_PAGEOUT); 643 UVM_PAGE_OWN(p, NULL); 644 uvmexp.paging--; 645 uvm_pageactivate(p); 646 simple_unlock(slock); 647 continue; 648 } 649 simple_unlock(slock); 650 } 651 swpps[swcpages] = p; 652 swcpages++; 653 654 /* 655 * if the cluster isn't full, look for more pages 656 * before starting the i/o. 657 */ 658 659 if (swcpages < swnpages) { 660 continue; 661 } 662 } 663 664 /* 665 * if this is the final pageout we could have a few 666 * unused swap blocks. if so, free them now. 667 */ 668 669 if (swcpages < swnpages) { 670 uvm_swap_free(swslot + swcpages, (swnpages - swcpages)); 671 } 672 673 /* 674 * now start the pageout. 675 */ 676 677 uvm_unlock_pageq(); 678 uvmexp.pdpageouts++; 679 error = uvm_swap_put(swslot, swpps, swcpages, 0); 680 KASSERT(error == 0); 681 uvm_lock_pageq(); 682 683 /* 684 * zero swslot to indicate that we are 685 * no longer building a swap-backed cluster. 686 */ 687 688 swslot = 0; 689 690 /* 691 * the pageout is in progress. bump counters and set up 692 * for the next loop. 693 */ 694 695 uvmexp.pdpending++; 696 if (nextpg && (nextpg->pqflags & PQ_INACTIVE) == 0) { 697 nextpg = TAILQ_FIRST(pglst); 698 } 699 } 700 return (error); 701 } 702 703 /* 704 * uvmpd_scan: scan the page queues and attempt to meet our targets. 705 * 706 * => called with pageq's locked 707 */ 708 709 void 710 uvmpd_scan(void) 711 { 712 int inactive_shortage, swap_shortage, pages_freed; 713 struct vm_page *p, *nextpg; 714 struct uvm_object *uobj; 715 struct vm_anon *anon; 716 boolean_t got_it; 717 UVMHIST_FUNC("uvmpd_scan"); UVMHIST_CALLED(pdhist); 718 719 uvmexp.pdrevs++; 720 uobj = NULL; 721 anon = NULL; 722 723 #ifndef __SWAP_BROKEN 724 725 /* 726 * swap out some processes if we are below our free target. 727 * we need to unlock the page queues for this. 728 */ 729 730 if (uvmexp.free < uvmexp.freetarg && uvmexp.nswapdev != 0) { 731 uvmexp.pdswout++; 732 UVMHIST_LOG(pdhist," free %d < target %d: swapout", 733 uvmexp.free, uvmexp.freetarg, 0, 0); 734 uvm_unlock_pageq(); 735 uvm_swapout_threads(); 736 uvm_lock_pageq(); 737 738 } 739 #endif 740 741 /* 742 * now we want to work on meeting our targets. first we work on our 743 * free target by converting inactive pages into free pages. then 744 * we work on meeting our inactive target by converting active pages 745 * to inactive ones. 746 */ 747 748 UVMHIST_LOG(pdhist, " starting 'free' loop",0,0,0,0); 749 750 /* 751 * alternate starting queue between swap and object based on the 752 * low bit of uvmexp.pdrevs (which we bump by one each call). 753 */ 754 755 got_it = FALSE; 756 pages_freed = uvmexp.pdfreed; 757 (void) uvmpd_scan_inactive(&uvm.page_inactive); 758 pages_freed = uvmexp.pdfreed - pages_freed; 759 760 /* 761 * we have done the scan to get free pages. now we work on meeting 762 * our inactive target. 763 */ 764 765 inactive_shortage = uvmexp.inactarg - uvmexp.inactive; 766 767 /* 768 * detect if we're not going to be able to page anything out 769 * until we free some swap resources from active pages. 770 */ 771 772 swap_shortage = 0; 773 if (uvmexp.free < uvmexp.freetarg && 774 uvmexp.swpginuse == uvmexp.swpages && 775 uvmexp.swpgonly < uvmexp.swpages && 776 pages_freed == 0) { 777 swap_shortage = uvmexp.freetarg - uvmexp.free; 778 } 779 780 UVMHIST_LOG(pdhist, " loop 2: inactive_shortage=%d swap_shortage=%d", 781 inactive_shortage, swap_shortage,0,0); 782 for (p = TAILQ_FIRST(&uvm.page_active); 783 p != NULL && (inactive_shortage > 0 || swap_shortage > 0); 784 p = nextpg) { 785 nextpg = TAILQ_NEXT(p, pageq); 786 if (p->flags & PG_BUSY) { 787 continue; 788 } 789 790 /* 791 * lock the page's owner. 792 */ 793 /* is page anon owned or ownerless? */ 794 if ((p->pqflags & PQ_ANON) || p->uobject == NULL) { 795 anon = p->uanon; 796 KASSERT(anon != NULL); 797 if (!simple_lock_try(&anon->an_lock)) { 798 continue; 799 } 800 801 /* take over the page? */ 802 if ((p->pqflags & PQ_ANON) == 0) { 803 KASSERT(p->loan_count > 0); 804 p->loan_count--; 805 p->pqflags |= PQ_ANON; 806 } 807 } else { 808 uobj = p->uobject; 809 if (!simple_lock_try(&uobj->vmobjlock)) { 810 continue; 811 } 812 } 813 814 /* 815 * skip this page if it's busy. 816 */ 817 818 if ((p->flags & PG_BUSY) != 0) { 819 if (p->pqflags & PQ_ANON) 820 simple_unlock(&anon->an_lock); 821 else 822 simple_unlock(&uobj->vmobjlock); 823 continue; 824 } 825 826 /* 827 * if there's a shortage of swap, free any swap allocated 828 * to this page so that other pages can be paged out. 829 */ 830 831 if (swap_shortage > 0) { 832 if ((p->pqflags & PQ_ANON) && anon->an_swslot) { 833 uvm_swap_free(anon->an_swslot, 1); 834 anon->an_swslot = 0; 835 p->flags &= ~PG_CLEAN; 836 swap_shortage--; 837 } else if (p->pqflags & PQ_AOBJ) { 838 int slot = uao_set_swslot(uobj, 839 p->offset >> PAGE_SHIFT, 0); 840 if (slot) { 841 uvm_swap_free(slot, 1); 842 p->flags &= ~PG_CLEAN; 843 swap_shortage--; 844 } 845 } 846 } 847 848 /* 849 * if there's a shortage of inactive pages, deactivate. 850 */ 851 852 if (inactive_shortage > 0) { 853 /* no need to check wire_count as pg is "active" */ 854 uvm_pagedeactivate(p); 855 uvmexp.pddeact++; 856 inactive_shortage--; 857 } 858 859 /* 860 * we're done with this page. 861 */ 862 863 if (p->pqflags & PQ_ANON) 864 simple_unlock(&anon->an_lock); 865 else 866 simple_unlock(&uobj->vmobjlock); 867 } 868 } 869