1 /* $NetBSD: uvm_pdaemon.c,v 1.59 2004/03/24 07:55:01 junyoung 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 1.59 2004/03/24 07:55:01 junyoung Exp $"); 75 76 #include "opt_uvmhist.h" 77 78 #include <sys/param.h> 79 #include <sys/proc.h> 80 #include <sys/systm.h> 81 #include <sys/kernel.h> 82 #include <sys/pool.h> 83 #include <sys/buf.h> 84 #include <sys/vnode.h> 85 86 #include <uvm/uvm.h> 87 88 /* 89 * UVMPD_NUMDIRTYREACTS is how many dirty pages the pagedaemon will reactivate 90 * in a pass thru the inactive list when swap is full. the value should be 91 * "small"... if it's too large we'll cycle the active pages thru the inactive 92 * queue too quickly to for them to be referenced and avoid being freed. 93 */ 94 95 #define UVMPD_NUMDIRTYREACTS 16 96 97 98 /* 99 * local prototypes 100 */ 101 102 void uvmpd_scan(void); 103 void uvmpd_scan_inactive(struct pglist *); 104 void uvmpd_tune(void); 105 106 /* 107 * uvm_wait: wait (sleep) for the page daemon to free some pages 108 * 109 * => should be called with all locks released 110 * => should _not_ be called by the page daemon (to avoid deadlock) 111 */ 112 113 void 114 uvm_wait(wmsg) 115 const char *wmsg; 116 { 117 int timo = 0; 118 int s = splbio(); 119 120 /* 121 * check for page daemon going to sleep (waiting for itself) 122 */ 123 124 if (curproc == uvm.pagedaemon_proc && uvmexp.paging == 0) { 125 /* 126 * now we have a problem: the pagedaemon wants to go to 127 * sleep until it frees more memory. but how can it 128 * free more memory if it is asleep? that is a deadlock. 129 * we have two options: 130 * [1] panic now 131 * [2] put a timeout on the sleep, thus causing the 132 * pagedaemon to only pause (rather than sleep forever) 133 * 134 * note that option [2] will only help us if we get lucky 135 * and some other process on the system breaks the deadlock 136 * by exiting or freeing memory (thus allowing the pagedaemon 137 * to continue). for now we panic if DEBUG is defined, 138 * otherwise we hope for the best with option [2] (better 139 * yet, this should never happen in the first place!). 140 */ 141 142 printf("pagedaemon: deadlock detected!\n"); 143 timo = hz >> 3; /* set timeout */ 144 #if defined(DEBUG) 145 /* DEBUG: panic so we can debug it */ 146 panic("pagedaemon deadlock"); 147 #endif 148 } 149 150 simple_lock(&uvm.pagedaemon_lock); 151 wakeup(&uvm.pagedaemon); /* wake the daemon! */ 152 UVM_UNLOCK_AND_WAIT(&uvmexp.free, &uvm.pagedaemon_lock, FALSE, wmsg, 153 timo); 154 155 splx(s); 156 } 157 158 159 /* 160 * uvmpd_tune: tune paging parameters 161 * 162 * => called when ever memory is added (or removed?) to the system 163 * => caller must call with page queues locked 164 */ 165 166 void 167 uvmpd_tune(void) 168 { 169 UVMHIST_FUNC("uvmpd_tune"); UVMHIST_CALLED(pdhist); 170 171 uvmexp.freemin = uvmexp.npages / 20; 172 173 /* between 16k and 256k */ 174 /* XXX: what are these values good for? */ 175 uvmexp.freemin = MAX(uvmexp.freemin, (16*1024) >> PAGE_SHIFT); 176 uvmexp.freemin = MIN(uvmexp.freemin, (256*1024) >> PAGE_SHIFT); 177 178 /* Make sure there's always a user page free. */ 179 if (uvmexp.freemin < uvmexp.reserve_kernel + 1) 180 uvmexp.freemin = uvmexp.reserve_kernel + 1; 181 182 uvmexp.freetarg = (uvmexp.freemin * 4) / 3; 183 if (uvmexp.freetarg <= uvmexp.freemin) 184 uvmexp.freetarg = uvmexp.freemin + 1; 185 186 /* uvmexp.inactarg: computed in main daemon loop */ 187 188 uvmexp.wiredmax = uvmexp.npages / 3; 189 UVMHIST_LOG(pdhist, "<- done, freemin=%d, freetarg=%d, wiredmax=%d", 190 uvmexp.freemin, uvmexp.freetarg, uvmexp.wiredmax, 0); 191 } 192 193 /* 194 * uvm_pageout: the main loop for the pagedaemon 195 */ 196 197 void 198 uvm_pageout(void *arg) 199 { 200 int npages = 0; 201 UVMHIST_FUNC("uvm_pageout"); UVMHIST_CALLED(pdhist); 202 203 UVMHIST_LOG(pdhist,"<starting uvm pagedaemon>", 0, 0, 0, 0); 204 205 /* 206 * ensure correct priority and set paging parameters... 207 */ 208 209 uvm.pagedaemon_proc = curproc; 210 uvm_lock_pageq(); 211 npages = uvmexp.npages; 212 uvmpd_tune(); 213 uvm_unlock_pageq(); 214 215 /* 216 * main loop 217 */ 218 219 for (;;) { 220 simple_lock(&uvm.pagedaemon_lock); 221 222 UVMHIST_LOG(pdhist," <<SLEEPING>>",0,0,0,0); 223 UVM_UNLOCK_AND_WAIT(&uvm.pagedaemon, 224 &uvm.pagedaemon_lock, FALSE, "pgdaemon", 0); 225 uvmexp.pdwoke++; 226 UVMHIST_LOG(pdhist," <<WOKE UP>>",0,0,0,0); 227 228 /* 229 * The metadata cache drainer knows about uvmexp.free 230 * and uvmexp.freetarg. We call it _before_ scanning 231 * so that it sees the amount we really want. 232 */ 233 buf_drain(0); 234 235 /* 236 * now lock page queues and recompute inactive count 237 */ 238 239 uvm_lock_pageq(); 240 if (npages != uvmexp.npages) { /* check for new pages? */ 241 npages = uvmexp.npages; 242 uvmpd_tune(); 243 } 244 245 uvmexp.inactarg = (uvmexp.active + uvmexp.inactive) / 3; 246 if (uvmexp.inactarg <= uvmexp.freetarg) { 247 uvmexp.inactarg = uvmexp.freetarg + 1; 248 } 249 250 UVMHIST_LOG(pdhist," free/ftarg=%d/%d, inact/itarg=%d/%d", 251 uvmexp.free, uvmexp.freetarg, uvmexp.inactive, 252 uvmexp.inactarg); 253 254 /* 255 * scan if needed 256 */ 257 258 if (uvmexp.free + uvmexp.paging < uvmexp.freetarg || 259 uvmexp.inactive < uvmexp.inactarg) { 260 uvmpd_scan(); 261 } 262 263 /* 264 * if there's any free memory to be had, 265 * wake up any waiters. 266 */ 267 268 if (uvmexp.free > uvmexp.reserve_kernel || 269 uvmexp.paging == 0) { 270 wakeup(&uvmexp.free); 271 } 272 273 /* 274 * scan done. unlock page queues (the only lock we are holding) 275 */ 276 277 uvm_unlock_pageq(); 278 279 /* 280 * drain pool resources now that we're not holding any locks 281 */ 282 283 pool_drain(0); 284 285 /* 286 * free any cached u-areas we don't need 287 */ 288 uvm_uarea_drain(TRUE); 289 290 } 291 /*NOTREACHED*/ 292 } 293 294 295 /* 296 * uvm_aiodone_daemon: main loop for the aiodone daemon. 297 */ 298 299 void 300 uvm_aiodone_daemon(void *arg) 301 { 302 int s, free; 303 struct buf *bp, *nbp; 304 UVMHIST_FUNC("uvm_aiodoned"); UVMHIST_CALLED(pdhist); 305 306 for (;;) { 307 308 /* 309 * carefully attempt to go to sleep (without losing "wakeups"!). 310 * we need splbio because we want to make sure the aio_done list 311 * is totally empty before we go to sleep. 312 */ 313 314 s = splbio(); 315 simple_lock(&uvm.aiodoned_lock); 316 if (TAILQ_FIRST(&uvm.aio_done) == NULL) { 317 UVMHIST_LOG(pdhist," <<SLEEPING>>",0,0,0,0); 318 UVM_UNLOCK_AND_WAIT(&uvm.aiodoned, 319 &uvm.aiodoned_lock, FALSE, "aiodoned", 0); 320 UVMHIST_LOG(pdhist," <<WOKE UP>>",0,0,0,0); 321 322 /* relock aiodoned_lock, still at splbio */ 323 simple_lock(&uvm.aiodoned_lock); 324 } 325 326 /* 327 * check for done aio structures 328 */ 329 330 bp = TAILQ_FIRST(&uvm.aio_done); 331 if (bp) { 332 TAILQ_INIT(&uvm.aio_done); 333 } 334 335 simple_unlock(&uvm.aiodoned_lock); 336 splx(s); 337 338 /* 339 * process each i/o that's done. 340 */ 341 342 free = uvmexp.free; 343 while (bp != NULL) { 344 nbp = TAILQ_NEXT(bp, b_freelist); 345 (*bp->b_iodone)(bp); 346 bp = nbp; 347 } 348 if (free <= uvmexp.reserve_kernel) { 349 s = uvm_lock_fpageq(); 350 wakeup(&uvm.pagedaemon); 351 uvm_unlock_fpageq(s); 352 } else { 353 simple_lock(&uvm.pagedaemon_lock); 354 wakeup(&uvmexp.free); 355 simple_unlock(&uvm.pagedaemon_lock); 356 } 357 } 358 } 359 360 /* 361 * uvmpd_scan_inactive: scan an inactive list for pages to clean or free. 362 * 363 * => called with page queues locked 364 * => we work on meeting our free target by converting inactive pages 365 * into free pages. 366 * => we handle the building of swap-backed clusters 367 * => we return TRUE if we are exiting because we met our target 368 */ 369 370 void 371 uvmpd_scan_inactive(pglst) 372 struct pglist *pglst; 373 { 374 int error; 375 struct vm_page *p, *nextpg = NULL; /* Quell compiler warning */ 376 struct uvm_object *uobj; 377 struct vm_anon *anon; 378 struct vm_page *swpps[round_page(MAXPHYS) >> PAGE_SHIFT]; 379 struct simplelock *slock; 380 int swnpages, swcpages; 381 int swslot; 382 int dirtyreacts, t, result; 383 boolean_t anonunder, fileunder, execunder; 384 boolean_t anonover, fileover, execover; 385 boolean_t anonreact, filereact, execreact; 386 UVMHIST_FUNC("uvmpd_scan_inactive"); UVMHIST_CALLED(pdhist); 387 388 /* 389 * swslot is non-zero if we are building a swap cluster. we want 390 * to stay in the loop while we have a page to scan or we have 391 * a swap-cluster to build. 392 */ 393 394 swslot = 0; 395 swnpages = swcpages = 0; 396 dirtyreacts = 0; 397 398 /* 399 * decide which types of pages we want to reactivate instead of freeing 400 * to keep usage within the minimum and maximum usage limits. 401 */ 402 403 t = uvmexp.active + uvmexp.inactive + uvmexp.free; 404 anonunder = (uvmexp.anonpages <= (t * uvmexp.anonmin) >> 8); 405 fileunder = (uvmexp.filepages <= (t * uvmexp.filemin) >> 8); 406 execunder = (uvmexp.execpages <= (t * uvmexp.execmin) >> 8); 407 anonover = uvmexp.anonpages > ((t * uvmexp.anonmax) >> 8); 408 fileover = uvmexp.filepages > ((t * uvmexp.filemax) >> 8); 409 execover = uvmexp.execpages > ((t * uvmexp.execmax) >> 8); 410 anonreact = anonunder || (!anonover && (fileover || execover)); 411 filereact = fileunder || (!fileover && (anonover || execover)); 412 execreact = execunder || (!execover && (anonover || fileover)); 413 for (p = TAILQ_FIRST(pglst); p != NULL || swslot != 0; p = nextpg) { 414 uobj = NULL; 415 anon = NULL; 416 if (p) { 417 418 /* 419 * see if we've met the free target. 420 */ 421 422 if (uvmexp.free + uvmexp.paging >= 423 uvmexp.freetarg << 2 || 424 dirtyreacts == UVMPD_NUMDIRTYREACTS) { 425 UVMHIST_LOG(pdhist," met free target: " 426 "exit loop", 0, 0, 0, 0); 427 428 if (swslot == 0) { 429 /* exit now if no swap-i/o pending */ 430 break; 431 } 432 433 /* set p to null to signal final swap i/o */ 434 p = NULL; 435 nextpg = NULL; 436 } 437 } 438 if (p) { /* if (we have a new page to consider) */ 439 440 /* 441 * we are below target and have a new page to consider. 442 */ 443 444 uvmexp.pdscans++; 445 nextpg = TAILQ_NEXT(p, pageq); 446 447 /* 448 * move referenced pages back to active queue and 449 * skip to next page. 450 */ 451 452 if (pmap_clear_reference(p)) { 453 uvm_pageactivate(p); 454 uvmexp.pdreact++; 455 continue; 456 } 457 anon = p->uanon; 458 uobj = p->uobject; 459 460 /* 461 * enforce the minimum thresholds on different 462 * types of memory usage. if reusing the current 463 * page would reduce that type of usage below its 464 * minimum, reactivate the page instead and move 465 * on to the next page. 466 */ 467 468 if (uobj && UVM_OBJ_IS_VTEXT(uobj) && execreact) { 469 uvm_pageactivate(p); 470 uvmexp.pdreexec++; 471 continue; 472 } 473 if (uobj && UVM_OBJ_IS_VNODE(uobj) && 474 !UVM_OBJ_IS_VTEXT(uobj) && filereact) { 475 uvm_pageactivate(p); 476 uvmexp.pdrefile++; 477 continue; 478 } 479 if ((anon || UVM_OBJ_IS_AOBJ(uobj)) && anonreact) { 480 uvm_pageactivate(p); 481 uvmexp.pdreanon++; 482 continue; 483 } 484 485 /* 486 * first we attempt to lock the object that this page 487 * belongs to. if our attempt fails we skip on to 488 * the next page (no harm done). it is important to 489 * "try" locking the object as we are locking in the 490 * wrong order (pageq -> object) and we don't want to 491 * deadlock. 492 * 493 * the only time we expect to see an ownerless page 494 * (i.e. a page with no uobject and !PQ_ANON) is if an 495 * anon has loaned a page from a uvm_object and the 496 * uvm_object has dropped the ownership. in that 497 * case, the anon can "take over" the loaned page 498 * and make it its own. 499 */ 500 501 /* does the page belong to an object? */ 502 if (uobj != NULL) { 503 slock = &uobj->vmobjlock; 504 if (!simple_lock_try(slock)) { 505 continue; 506 } 507 if (p->flags & PG_BUSY) { 508 simple_unlock(slock); 509 uvmexp.pdbusy++; 510 continue; 511 } 512 uvmexp.pdobscan++; 513 } else { 514 KASSERT(anon != NULL); 515 slock = &anon->an_lock; 516 if (!simple_lock_try(slock)) { 517 continue; 518 } 519 520 /* 521 * set PQ_ANON if it isn't set already. 522 */ 523 524 if ((p->pqflags & PQ_ANON) == 0) { 525 KASSERT(p->loan_count > 0); 526 p->loan_count--; 527 p->pqflags |= PQ_ANON; 528 /* anon now owns it */ 529 } 530 if (p->flags & PG_BUSY) { 531 simple_unlock(slock); 532 uvmexp.pdbusy++; 533 continue; 534 } 535 uvmexp.pdanscan++; 536 } 537 538 539 /* 540 * we now have the object and the page queues locked. 541 * if the page is not swap-backed, call the object's 542 * pager to flush and free the page. 543 */ 544 545 if ((p->pqflags & PQ_SWAPBACKED) == 0) { 546 uvm_unlock_pageq(); 547 (void) (uobj->pgops->pgo_put)(uobj, p->offset, 548 p->offset + PAGE_SIZE, 549 PGO_CLEANIT|PGO_FREE); 550 uvm_lock_pageq(); 551 if (nextpg && 552 (nextpg->pqflags & PQ_INACTIVE) == 0) { 553 nextpg = TAILQ_FIRST(pglst); 554 } 555 continue; 556 } 557 558 /* 559 * the page is swap-backed. remove all the permissions 560 * from the page so we can sync the modified info 561 * without any race conditions. if the page is clean 562 * we can free it now and continue. 563 */ 564 565 pmap_page_protect(p, VM_PROT_NONE); 566 if ((p->flags & PG_CLEAN) && pmap_clear_modify(p)) { 567 p->flags &= ~(PG_CLEAN); 568 } 569 if (p->flags & PG_CLEAN) { 570 int slot; 571 int pageidx; 572 573 pageidx = p->offset >> PAGE_SHIFT; 574 uvm_pagefree(p); 575 uvmexp.pdfreed++; 576 577 /* 578 * for anons, we need to remove the page 579 * from the anon ourselves. for aobjs, 580 * pagefree did that for us. 581 */ 582 583 if (anon) { 584 KASSERT(anon->an_swslot != 0); 585 anon->u.an_page = NULL; 586 slot = anon->an_swslot; 587 } else { 588 slot = uao_find_swslot(uobj, pageidx); 589 } 590 simple_unlock(slock); 591 592 if (slot > 0) { 593 /* this page is now only in swap. */ 594 simple_lock(&uvm.swap_data_lock); 595 KASSERT(uvmexp.swpgonly < 596 uvmexp.swpginuse); 597 uvmexp.swpgonly++; 598 simple_unlock(&uvm.swap_data_lock); 599 } 600 continue; 601 } 602 603 /* 604 * this page is dirty, skip it if we'll have met our 605 * free target when all the current pageouts complete. 606 */ 607 608 if (uvmexp.free + uvmexp.paging > 609 uvmexp.freetarg << 2) { 610 simple_unlock(slock); 611 continue; 612 } 613 614 /* 615 * free any swap space allocated to the page since 616 * we'll have to write it again with its new data. 617 */ 618 619 if ((p->pqflags & PQ_ANON) && anon->an_swslot) { 620 uvm_swap_free(anon->an_swslot, 1); 621 anon->an_swslot = 0; 622 } else if (p->pqflags & PQ_AOBJ) { 623 uao_dropswap(uobj, p->offset >> PAGE_SHIFT); 624 } 625 626 /* 627 * if all pages in swap are only in swap, 628 * the swap space is full and we can't page out 629 * any more swap-backed pages. reactivate this page 630 * so that we eventually cycle all pages through 631 * the inactive queue. 632 */ 633 634 if (uvm_swapisfull()) { 635 dirtyreacts++; 636 uvm_pageactivate(p); 637 simple_unlock(slock); 638 continue; 639 } 640 641 /* 642 * start new swap pageout cluster (if necessary). 643 */ 644 645 if (swslot == 0) { 646 /* Even with strange MAXPHYS, the shift 647 implicitly rounds down to a page. */ 648 swnpages = MAXPHYS >> PAGE_SHIFT; 649 swslot = uvm_swap_alloc(&swnpages, TRUE); 650 if (swslot == 0) { 651 simple_unlock(slock); 652 continue; 653 } 654 swcpages = 0; 655 } 656 657 /* 658 * at this point, we're definitely going reuse this 659 * page. mark the page busy and delayed-free. 660 * we should remove the page from the page queues 661 * so we don't ever look at it again. 662 * adjust counters and such. 663 */ 664 665 p->flags |= PG_BUSY; 666 UVM_PAGE_OWN(p, "scan_inactive"); 667 668 p->flags |= PG_PAGEOUT; 669 uvmexp.paging++; 670 uvm_pagedequeue(p); 671 672 uvmexp.pgswapout++; 673 674 /* 675 * add the new page to the cluster. 676 */ 677 678 if (anon) { 679 anon->an_swslot = swslot + swcpages; 680 simple_unlock(slock); 681 } else { 682 result = uao_set_swslot(uobj, 683 p->offset >> PAGE_SHIFT, swslot + swcpages); 684 if (result == -1) { 685 p->flags &= ~(PG_BUSY|PG_PAGEOUT); 686 UVM_PAGE_OWN(p, NULL); 687 uvmexp.paging--; 688 uvm_pageactivate(p); 689 simple_unlock(slock); 690 continue; 691 } 692 simple_unlock(slock); 693 } 694 swpps[swcpages] = p; 695 swcpages++; 696 697 /* 698 * if the cluster isn't full, look for more pages 699 * before starting the i/o. 700 */ 701 702 if (swcpages < swnpages) { 703 continue; 704 } 705 } 706 707 /* 708 * if this is the final pageout we could have a few 709 * unused swap blocks. if so, free them now. 710 */ 711 712 if (swcpages < swnpages) { 713 uvm_swap_free(swslot + swcpages, (swnpages - swcpages)); 714 } 715 716 /* 717 * now start the pageout. 718 */ 719 720 uvm_unlock_pageq(); 721 uvmexp.pdpageouts++; 722 error = uvm_swap_put(swslot, swpps, swcpages, 0); 723 KASSERT(error == 0); 724 uvm_lock_pageq(); 725 726 /* 727 * zero swslot to indicate that we are 728 * no longer building a swap-backed cluster. 729 */ 730 731 swslot = 0; 732 733 /* 734 * the pageout is in progress. bump counters and set up 735 * for the next loop. 736 */ 737 738 uvmexp.pdpending++; 739 if (nextpg && (nextpg->pqflags & PQ_INACTIVE) == 0) { 740 nextpg = TAILQ_FIRST(pglst); 741 } 742 } 743 } 744 745 /* 746 * uvmpd_scan: scan the page queues and attempt to meet our targets. 747 * 748 * => called with pageq's locked 749 */ 750 751 void 752 uvmpd_scan(void) 753 { 754 int inactive_shortage, swap_shortage, pages_freed; 755 struct vm_page *p, *nextpg; 756 struct uvm_object *uobj; 757 struct vm_anon *anon; 758 struct simplelock *slock; 759 UVMHIST_FUNC("uvmpd_scan"); UVMHIST_CALLED(pdhist); 760 761 uvmexp.pdrevs++; 762 uobj = NULL; 763 anon = NULL; 764 765 #ifndef __SWAP_BROKEN 766 767 /* 768 * swap out some processes if we are below our free target. 769 * we need to unlock the page queues for this. 770 */ 771 772 if (uvmexp.free < uvmexp.freetarg && uvmexp.nswapdev != 0) { 773 uvmexp.pdswout++; 774 UVMHIST_LOG(pdhist," free %d < target %d: swapout", 775 uvmexp.free, uvmexp.freetarg, 0, 0); 776 uvm_unlock_pageq(); 777 uvm_swapout_threads(); 778 uvm_lock_pageq(); 779 780 } 781 #endif 782 783 /* 784 * now we want to work on meeting our targets. first we work on our 785 * free target by converting inactive pages into free pages. then 786 * we work on meeting our inactive target by converting active pages 787 * to inactive ones. 788 */ 789 790 UVMHIST_LOG(pdhist, " starting 'free' loop",0,0,0,0); 791 792 pages_freed = uvmexp.pdfreed; 793 uvmpd_scan_inactive(&uvm.page_inactive); 794 pages_freed = uvmexp.pdfreed - pages_freed; 795 796 /* 797 * we have done the scan to get free pages. now we work on meeting 798 * our inactive target. 799 */ 800 801 inactive_shortage = uvmexp.inactarg - uvmexp.inactive; 802 803 /* 804 * detect if we're not going to be able to page anything out 805 * until we free some swap resources from active pages. 806 */ 807 808 swap_shortage = 0; 809 if (uvmexp.free < uvmexp.freetarg && 810 uvmexp.swpginuse >= uvmexp.swpgavail && 811 !uvm_swapisfull() && 812 pages_freed == 0) { 813 swap_shortage = uvmexp.freetarg - uvmexp.free; 814 } 815 816 UVMHIST_LOG(pdhist, " loop 2: inactive_shortage=%d swap_shortage=%d", 817 inactive_shortage, swap_shortage,0,0); 818 for (p = TAILQ_FIRST(&uvm.page_active); 819 p != NULL && (inactive_shortage > 0 || swap_shortage > 0); 820 p = nextpg) { 821 nextpg = TAILQ_NEXT(p, pageq); 822 if (p->flags & PG_BUSY) { 823 continue; 824 } 825 826 /* 827 * lock the page's owner. 828 */ 829 830 if (p->uobject != NULL) { 831 uobj = p->uobject; 832 slock = &uobj->vmobjlock; 833 if (!simple_lock_try(slock)) { 834 continue; 835 } 836 } else { 837 anon = p->uanon; 838 KASSERT(anon != NULL); 839 slock = &anon->an_lock; 840 if (!simple_lock_try(slock)) { 841 continue; 842 } 843 844 /* take over the page? */ 845 if ((p->pqflags & PQ_ANON) == 0) { 846 KASSERT(p->loan_count > 0); 847 p->loan_count--; 848 p->pqflags |= PQ_ANON; 849 } 850 } 851 852 /* 853 * skip this page if it's busy. 854 */ 855 856 if ((p->flags & PG_BUSY) != 0) { 857 simple_unlock(slock); 858 continue; 859 } 860 861 /* 862 * if there's a shortage of swap, free any swap allocated 863 * to this page so that other pages can be paged out. 864 */ 865 866 if (swap_shortage > 0) { 867 if ((p->pqflags & PQ_ANON) && anon->an_swslot) { 868 uvm_swap_free(anon->an_swslot, 1); 869 anon->an_swslot = 0; 870 p->flags &= ~PG_CLEAN; 871 swap_shortage--; 872 } else if (p->pqflags & PQ_AOBJ) { 873 int slot = uao_set_swslot(uobj, 874 p->offset >> PAGE_SHIFT, 0); 875 if (slot) { 876 uvm_swap_free(slot, 1); 877 p->flags &= ~PG_CLEAN; 878 swap_shortage--; 879 } 880 } 881 } 882 883 /* 884 * if there's a shortage of inactive pages, deactivate. 885 */ 886 887 if (inactive_shortage > 0) { 888 /* no need to check wire_count as pg is "active" */ 889 uvm_pagedeactivate(p); 890 uvmexp.pddeact++; 891 inactive_shortage--; 892 } 893 894 /* 895 * we're done with this page. 896 */ 897 898 simple_unlock(slock); 899 } 900 } 901