1 /* $NetBSD: uvm_pdaemon.c,v 1.62 2005/04/12 13:11:45 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 1.62 2005/04/12 13:11:45 yamt 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 * XXX hack to avoid hangs when large processes fork. 108 */ 109 int uvm_extrapages; 110 111 /* 112 * uvm_wait: wait (sleep) for the page daemon to free some pages 113 * 114 * => should be called with all locks released 115 * => should _not_ be called by the page daemon (to avoid deadlock) 116 */ 117 118 void 119 uvm_wait(wmsg) 120 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 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 void 384 uvmpd_scan_inactive(pglst) 385 struct pglist *pglst; 386 { 387 int error; 388 struct vm_page *p, *nextpg = NULL; /* Quell compiler warning */ 389 struct uvm_object *uobj; 390 struct vm_anon *anon; 391 struct vm_page *swpps[round_page(MAXPHYS) >> PAGE_SHIFT]; 392 struct simplelock *slock; 393 int swnpages, swcpages; 394 int swslot; 395 int dirtyreacts, t, result; 396 boolean_t anonunder, fileunder, execunder; 397 boolean_t anonover, fileover, execover; 398 boolean_t anonreact, filereact, execreact; 399 UVMHIST_FUNC("uvmpd_scan_inactive"); UVMHIST_CALLED(pdhist); 400 401 /* 402 * swslot is non-zero if we are building a swap cluster. we want 403 * to stay in the loop while we have a page to scan or we have 404 * a swap-cluster to build. 405 */ 406 407 swslot = 0; 408 swnpages = swcpages = 0; 409 dirtyreacts = 0; 410 411 /* 412 * decide which types of pages we want to reactivate instead of freeing 413 * to keep usage within the minimum and maximum usage limits. 414 */ 415 416 t = uvmexp.active + uvmexp.inactive + uvmexp.free; 417 anonunder = (uvmexp.anonpages <= (t * uvmexp.anonmin) >> 8); 418 fileunder = (uvmexp.filepages <= (t * uvmexp.filemin) >> 8); 419 execunder = (uvmexp.execpages <= (t * uvmexp.execmin) >> 8); 420 anonover = uvmexp.anonpages > ((t * uvmexp.anonmax) >> 8); 421 fileover = uvmexp.filepages > ((t * uvmexp.filemax) >> 8); 422 execover = uvmexp.execpages > ((t * uvmexp.execmax) >> 8); 423 anonreact = anonunder || (!anonover && (fileover || execover)); 424 filereact = fileunder || (!fileover && (anonover || execover)); 425 execreact = execunder || (!execover && (anonover || fileover)); 426 if (filereact && execreact && (anonreact || uvm_swapisfull())) { 427 anonreact = filereact = execreact = FALSE; 428 } 429 for (p = TAILQ_FIRST(pglst); p != NULL || swslot != 0; p = nextpg) { 430 uobj = NULL; 431 anon = NULL; 432 if (p) { 433 434 /* 435 * see if we've met the free target. 436 */ 437 438 if (uvmexp.free + uvmexp.paging >= 439 uvmexp.freetarg << 2 || 440 dirtyreacts == UVMPD_NUMDIRTYREACTS) { 441 UVMHIST_LOG(pdhist," met free target: " 442 "exit loop", 0, 0, 0, 0); 443 444 if (swslot == 0) { 445 /* exit now if no swap-i/o pending */ 446 break; 447 } 448 449 /* set p to null to signal final swap i/o */ 450 p = NULL; 451 nextpg = NULL; 452 } 453 } 454 if (p) { /* if (we have a new page to consider) */ 455 456 /* 457 * we are below target and have a new page to consider. 458 */ 459 460 uvmexp.pdscans++; 461 nextpg = TAILQ_NEXT(p, pageq); 462 463 /* 464 * move referenced pages back to active queue and 465 * skip to next page. 466 */ 467 468 if (pmap_clear_reference(p)) { 469 uvm_pageactivate(p); 470 uvmexp.pdreact++; 471 continue; 472 } 473 anon = p->uanon; 474 uobj = p->uobject; 475 476 /* 477 * enforce the minimum thresholds on different 478 * types of memory usage. if reusing the current 479 * page would reduce that type of usage below its 480 * minimum, reactivate the page instead and move 481 * on to the next page. 482 */ 483 484 if (uobj && UVM_OBJ_IS_VTEXT(uobj) && execreact) { 485 uvm_pageactivate(p); 486 uvmexp.pdreexec++; 487 continue; 488 } 489 if (uobj && UVM_OBJ_IS_VNODE(uobj) && 490 !UVM_OBJ_IS_VTEXT(uobj) && filereact) { 491 uvm_pageactivate(p); 492 uvmexp.pdrefile++; 493 continue; 494 } 495 if ((anon || UVM_OBJ_IS_AOBJ(uobj)) && anonreact) { 496 uvm_pageactivate(p); 497 uvmexp.pdreanon++; 498 continue; 499 } 500 501 /* 502 * first we attempt to lock the object that this page 503 * belongs to. if our attempt fails we skip on to 504 * the next page (no harm done). it is important to 505 * "try" locking the object as we are locking in the 506 * wrong order (pageq -> object) and we don't want to 507 * deadlock. 508 * 509 * the only time we expect to see an ownerless page 510 * (i.e. a page with no uobject and !PQ_ANON) is if an 511 * anon has loaned a page from a uvm_object and the 512 * uvm_object has dropped the ownership. in that 513 * case, the anon can "take over" the loaned page 514 * and make it its own. 515 */ 516 517 /* does the page belong to an object? */ 518 if (uobj != NULL) { 519 slock = &uobj->vmobjlock; 520 if (!simple_lock_try(slock)) { 521 continue; 522 } 523 if (p->flags & PG_BUSY) { 524 simple_unlock(slock); 525 uvmexp.pdbusy++; 526 continue; 527 } 528 uvmexp.pdobscan++; 529 } else { 530 KASSERT(anon != NULL); 531 slock = &anon->an_lock; 532 if (!simple_lock_try(slock)) { 533 continue; 534 } 535 536 /* 537 * set PQ_ANON if it isn't set already. 538 */ 539 540 if ((p->pqflags & PQ_ANON) == 0) { 541 KASSERT(p->loan_count > 0); 542 p->loan_count--; 543 p->pqflags |= PQ_ANON; 544 /* anon now owns it */ 545 } 546 if (p->flags & PG_BUSY) { 547 simple_unlock(slock); 548 uvmexp.pdbusy++; 549 continue; 550 } 551 uvmexp.pdanscan++; 552 } 553 554 555 /* 556 * we now have the object and the page queues locked. 557 * if the page is not swap-backed, call the object's 558 * pager to flush and free the page. 559 */ 560 561 if ((p->pqflags & PQ_SWAPBACKED) == 0) { 562 uvm_unlock_pageq(); 563 (void) (uobj->pgops->pgo_put)(uobj, p->offset, 564 p->offset + PAGE_SIZE, 565 PGO_CLEANIT|PGO_FREE); 566 uvm_lock_pageq(); 567 if (nextpg && 568 (nextpg->pqflags & PQ_INACTIVE) == 0) { 569 nextpg = TAILQ_FIRST(pglst); 570 } 571 continue; 572 } 573 574 /* 575 * the page is swap-backed. remove all the permissions 576 * from the page so we can sync the modified info 577 * without any race conditions. if the page is clean 578 * we can free it now and continue. 579 */ 580 581 pmap_page_protect(p, VM_PROT_NONE); 582 if ((p->flags & PG_CLEAN) && pmap_clear_modify(p)) { 583 p->flags &= ~(PG_CLEAN); 584 } 585 if (p->flags & PG_CLEAN) { 586 int slot; 587 int pageidx; 588 589 pageidx = p->offset >> PAGE_SHIFT; 590 uvm_pagefree(p); 591 uvmexp.pdfreed++; 592 593 /* 594 * for anons, we need to remove the page 595 * from the anon ourselves. for aobjs, 596 * pagefree did that for us. 597 */ 598 599 if (anon) { 600 KASSERT(anon->an_swslot != 0); 601 anon->u.an_page = NULL; 602 slot = anon->an_swslot; 603 } else { 604 slot = uao_find_swslot(uobj, pageidx); 605 } 606 simple_unlock(slock); 607 608 if (slot > 0) { 609 /* this page is now only in swap. */ 610 simple_lock(&uvm.swap_data_lock); 611 KASSERT(uvmexp.swpgonly < 612 uvmexp.swpginuse); 613 uvmexp.swpgonly++; 614 simple_unlock(&uvm.swap_data_lock); 615 } 616 continue; 617 } 618 619 /* 620 * this page is dirty, skip it if we'll have met our 621 * free target when all the current pageouts complete. 622 */ 623 624 if (uvmexp.free + uvmexp.paging > 625 uvmexp.freetarg << 2) { 626 simple_unlock(slock); 627 continue; 628 } 629 630 /* 631 * free any swap space allocated to the page since 632 * we'll have to write it again with its new data. 633 */ 634 635 if ((p->pqflags & PQ_ANON) && anon->an_swslot) { 636 uvm_swap_free(anon->an_swslot, 1); 637 anon->an_swslot = 0; 638 } else if (p->pqflags & PQ_AOBJ) { 639 uao_dropswap(uobj, p->offset >> PAGE_SHIFT); 640 } 641 642 /* 643 * if all pages in swap are only in swap, 644 * the swap space is full and we can't page out 645 * any more swap-backed pages. reactivate this page 646 * so that we eventually cycle all pages through 647 * the inactive queue. 648 */ 649 650 if (uvm_swapisfull()) { 651 dirtyreacts++; 652 uvm_pageactivate(p); 653 simple_unlock(slock); 654 continue; 655 } 656 657 /* 658 * start new swap pageout cluster (if necessary). 659 */ 660 661 if (swslot == 0) { 662 /* Even with strange MAXPHYS, the shift 663 implicitly rounds down to a page. */ 664 swnpages = MAXPHYS >> PAGE_SHIFT; 665 swslot = uvm_swap_alloc(&swnpages, TRUE); 666 if (swslot == 0) { 667 simple_unlock(slock); 668 continue; 669 } 670 swcpages = 0; 671 } 672 673 /* 674 * at this point, we're definitely going reuse this 675 * page. mark the page busy and delayed-free. 676 * we should remove the page from the page queues 677 * so we don't ever look at it again. 678 * adjust counters and such. 679 */ 680 681 p->flags |= PG_BUSY; 682 UVM_PAGE_OWN(p, "scan_inactive"); 683 684 p->flags |= PG_PAGEOUT; 685 uvmexp.paging++; 686 uvm_pagedequeue(p); 687 688 uvmexp.pgswapout++; 689 690 /* 691 * add the new page to the cluster. 692 */ 693 694 if (anon) { 695 anon->an_swslot = swslot + swcpages; 696 simple_unlock(slock); 697 } else { 698 result = uao_set_swslot(uobj, 699 p->offset >> PAGE_SHIFT, swslot + swcpages); 700 if (result == -1) { 701 p->flags &= ~(PG_BUSY|PG_PAGEOUT); 702 UVM_PAGE_OWN(p, NULL); 703 uvmexp.paging--; 704 uvm_pageactivate(p); 705 simple_unlock(slock); 706 continue; 707 } 708 simple_unlock(slock); 709 } 710 swpps[swcpages] = p; 711 swcpages++; 712 713 /* 714 * if the cluster isn't full, look for more pages 715 * before starting the i/o. 716 */ 717 718 if (swcpages < swnpages) { 719 continue; 720 } 721 } 722 723 /* 724 * if this is the final pageout we could have a few 725 * unused swap blocks. if so, free them now. 726 */ 727 728 if (swcpages < swnpages) { 729 uvm_swap_free(swslot + swcpages, (swnpages - swcpages)); 730 } 731 732 /* 733 * now start the pageout. 734 */ 735 736 uvm_unlock_pageq(); 737 uvmexp.pdpageouts++; 738 error = uvm_swap_put(swslot, swpps, swcpages, 0); 739 KASSERT(error == 0); 740 uvm_lock_pageq(); 741 742 /* 743 * zero swslot to indicate that we are 744 * no longer building a swap-backed cluster. 745 */ 746 747 swslot = 0; 748 749 /* 750 * the pageout is in progress. bump counters and set up 751 * for the next loop. 752 */ 753 754 uvmexp.pdpending++; 755 if (nextpg && (nextpg->pqflags & PQ_INACTIVE) == 0) { 756 nextpg = TAILQ_FIRST(pglst); 757 } 758 } 759 } 760 761 /* 762 * uvmpd_scan: scan the page queues and attempt to meet our targets. 763 * 764 * => called with pageq's locked 765 */ 766 767 void 768 uvmpd_scan(void) 769 { 770 int inactive_shortage, swap_shortage, pages_freed; 771 struct vm_page *p, *nextpg; 772 struct uvm_object *uobj; 773 struct vm_anon *anon; 774 struct simplelock *slock; 775 UVMHIST_FUNC("uvmpd_scan"); UVMHIST_CALLED(pdhist); 776 777 uvmexp.pdrevs++; 778 uobj = NULL; 779 anon = NULL; 780 781 #ifndef __SWAP_BROKEN 782 783 /* 784 * swap out some processes if we are below our free target. 785 * we need to unlock the page queues for this. 786 */ 787 788 if (uvmexp.free < uvmexp.freetarg && uvmexp.nswapdev != 0) { 789 uvmexp.pdswout++; 790 UVMHIST_LOG(pdhist," free %d < target %d: swapout", 791 uvmexp.free, uvmexp.freetarg, 0, 0); 792 uvm_unlock_pageq(); 793 uvm_swapout_threads(); 794 uvm_lock_pageq(); 795 796 } 797 #endif 798 799 /* 800 * now we want to work on meeting our targets. first we work on our 801 * free target by converting inactive pages into free pages. then 802 * we work on meeting our inactive target by converting active pages 803 * to inactive ones. 804 */ 805 806 UVMHIST_LOG(pdhist, " starting 'free' loop",0,0,0,0); 807 808 pages_freed = uvmexp.pdfreed; 809 uvmpd_scan_inactive(&uvm.page_inactive); 810 pages_freed = uvmexp.pdfreed - pages_freed; 811 812 /* 813 * we have done the scan to get free pages. now we work on meeting 814 * our inactive target. 815 */ 816 817 inactive_shortage = uvmexp.inactarg - uvmexp.inactive; 818 819 /* 820 * detect if we're not going to be able to page anything out 821 * until we free some swap resources from active pages. 822 */ 823 824 swap_shortage = 0; 825 if (uvmexp.free < uvmexp.freetarg && 826 uvmexp.swpginuse >= uvmexp.swpgavail && 827 !uvm_swapisfull() && 828 pages_freed == 0) { 829 swap_shortage = uvmexp.freetarg - uvmexp.free; 830 } 831 832 UVMHIST_LOG(pdhist, " loop 2: inactive_shortage=%d swap_shortage=%d", 833 inactive_shortage, swap_shortage,0,0); 834 for (p = TAILQ_FIRST(&uvm.page_active); 835 p != NULL && (inactive_shortage > 0 || swap_shortage > 0); 836 p = nextpg) { 837 nextpg = TAILQ_NEXT(p, pageq); 838 if (p->flags & PG_BUSY) { 839 continue; 840 } 841 842 /* 843 * lock the page's owner. 844 */ 845 846 if (p->uobject != NULL) { 847 uobj = p->uobject; 848 slock = &uobj->vmobjlock; 849 if (!simple_lock_try(slock)) { 850 continue; 851 } 852 } else { 853 anon = p->uanon; 854 KASSERT(anon != NULL); 855 slock = &anon->an_lock; 856 if (!simple_lock_try(slock)) { 857 continue; 858 } 859 860 /* take over the page? */ 861 if ((p->pqflags & PQ_ANON) == 0) { 862 KASSERT(p->loan_count > 0); 863 p->loan_count--; 864 p->pqflags |= PQ_ANON; 865 } 866 } 867 868 /* 869 * skip this page if it's busy. 870 */ 871 872 if ((p->flags & PG_BUSY) != 0) { 873 simple_unlock(slock); 874 continue; 875 } 876 877 /* 878 * if there's a shortage of swap, free any swap allocated 879 * to this page so that other pages can be paged out. 880 */ 881 882 if (swap_shortage > 0) { 883 if ((p->pqflags & PQ_ANON) && anon->an_swslot) { 884 uvm_swap_free(anon->an_swslot, 1); 885 anon->an_swslot = 0; 886 p->flags &= ~PG_CLEAN; 887 swap_shortage--; 888 } else if (p->pqflags & PQ_AOBJ) { 889 int slot = uao_set_swslot(uobj, 890 p->offset >> PAGE_SHIFT, 0); 891 if (slot) { 892 uvm_swap_free(slot, 1); 893 p->flags &= ~PG_CLEAN; 894 swap_shortage--; 895 } 896 } 897 } 898 899 /* 900 * if there's a shortage of inactive pages, deactivate. 901 */ 902 903 if (inactive_shortage > 0) { 904 /* no need to check wire_count as pg is "active" */ 905 uvm_pagedeactivate(p); 906 uvmexp.pddeact++; 907 inactive_shortage--; 908 } 909 910 /* 911 * we're done with this page. 912 */ 913 914 simple_unlock(slock); 915 } 916 } 917 918 /* 919 * uvm_reclaimable: decide whether to wait for pagedaemon. 920 * 921 * => return TRUE if it seems to be worth to do uvm_wait. 922 * 923 * XXX should be tunable. 924 * XXX should consider pools, etc? 925 */ 926 927 boolean_t 928 uvm_reclaimable(void) 929 { 930 int filepages; 931 932 /* 933 * if swap is not full, no problem. 934 */ 935 936 if (!uvm_swapisfull()) { 937 return TRUE; 938 } 939 940 /* 941 * file-backed pages can be reclaimed even when swap is full. 942 * if we have more than 1/16 of pageable memory or 5MB, try to reclaim. 943 * 944 * XXX assume the worst case, ie. all wired pages are file-backed. 945 */ 946 947 filepages = uvmexp.filepages + uvmexp.execpages - uvmexp.wired; 948 if (filepages >= MIN((uvmexp.active + uvmexp.inactive) >> 4, 949 5 * 1024 * 1024 >> PAGE_SHIFT)) { 950 return TRUE; 951 } 952 953 /* 954 * kill the process, fail allocation, etc.. 955 */ 956 957 return FALSE; 958 } 959