1 /* $NetBSD: uvm_pdaemon.c,v 1.72 2006/01/05 10:47:33 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 1.72 2006/01/05 10:47:33 yamt Exp $"); 75 76 #include "opt_uvmhist.h" 77 #include "opt_readahead.h" 78 79 #include <sys/param.h> 80 #include <sys/proc.h> 81 #include <sys/systm.h> 82 #include <sys/kernel.h> 83 #include <sys/pool.h> 84 #include <sys/buf.h> 85 #include <sys/vnode.h> 86 87 #include <uvm/uvm.h> 88 89 /* 90 * UVMPD_NUMDIRTYREACTS is how many dirty pages the pagedaemon will reactivate 91 * in a pass thru the inactive list when swap is full. the value should be 92 * "small"... if it's too large we'll cycle the active pages thru the inactive 93 * queue too quickly to for them to be referenced and avoid being freed. 94 */ 95 96 #define UVMPD_NUMDIRTYREACTS 16 97 98 99 /* 100 * local prototypes 101 */ 102 103 static void uvmpd_scan(void); 104 static void uvmpd_scan_inactive(struct pglist *); 105 static void uvmpd_tune(void); 106 107 /* 108 * XXX hack to avoid hangs when large processes fork. 109 */ 110 int uvm_extrapages; 111 112 /* 113 * uvm_wait: wait (sleep) for the page daemon to free some pages 114 * 115 * => should be called with all locks released 116 * => should _not_ be called by the page daemon (to avoid deadlock) 117 */ 118 119 void 120 uvm_wait(const char *wmsg) 121 { 122 int timo = 0; 123 int s = splbio(); 124 125 /* 126 * check for page daemon going to sleep (waiting for itself) 127 */ 128 129 if (curproc == uvm.pagedaemon_proc && uvmexp.paging == 0) { 130 /* 131 * now we have a problem: the pagedaemon wants to go to 132 * sleep until it frees more memory. but how can it 133 * free more memory if it is asleep? that is a deadlock. 134 * we have two options: 135 * [1] panic now 136 * [2] put a timeout on the sleep, thus causing the 137 * pagedaemon to only pause (rather than sleep forever) 138 * 139 * note that option [2] will only help us if we get lucky 140 * and some other process on the system breaks the deadlock 141 * by exiting or freeing memory (thus allowing the pagedaemon 142 * to continue). for now we panic if DEBUG is defined, 143 * otherwise we hope for the best with option [2] (better 144 * yet, this should never happen in the first place!). 145 */ 146 147 printf("pagedaemon: deadlock detected!\n"); 148 timo = hz >> 3; /* set timeout */ 149 #if defined(DEBUG) 150 /* DEBUG: panic so we can debug it */ 151 panic("pagedaemon deadlock"); 152 #endif 153 } 154 155 simple_lock(&uvm.pagedaemon_lock); 156 wakeup(&uvm.pagedaemon); /* wake the daemon! */ 157 UVM_UNLOCK_AND_WAIT(&uvmexp.free, &uvm.pagedaemon_lock, FALSE, wmsg, 158 timo); 159 160 splx(s); 161 } 162 163 164 /* 165 * uvmpd_tune: tune paging parameters 166 * 167 * => called when ever memory is added (or removed?) to the system 168 * => caller must call with page queues locked 169 */ 170 171 static void 172 uvmpd_tune(void) 173 { 174 UVMHIST_FUNC("uvmpd_tune"); UVMHIST_CALLED(pdhist); 175 176 uvmexp.freemin = uvmexp.npages / 20; 177 178 /* between 16k and 256k */ 179 /* XXX: what are these values good for? */ 180 uvmexp.freemin = MAX(uvmexp.freemin, (16*1024) >> PAGE_SHIFT); 181 uvmexp.freemin = MIN(uvmexp.freemin, (256*1024) >> PAGE_SHIFT); 182 183 /* Make sure there's always a user page free. */ 184 if (uvmexp.freemin < uvmexp.reserve_kernel + 1) 185 uvmexp.freemin = uvmexp.reserve_kernel + 1; 186 187 uvmexp.freetarg = (uvmexp.freemin * 4) / 3; 188 if (uvmexp.freetarg <= uvmexp.freemin) 189 uvmexp.freetarg = uvmexp.freemin + 1; 190 191 uvmexp.freetarg += uvm_extrapages; 192 uvm_extrapages = 0; 193 194 /* uvmexp.inactarg: computed in main daemon loop */ 195 196 uvmexp.wiredmax = uvmexp.npages / 3; 197 UVMHIST_LOG(pdhist, "<- done, freemin=%d, freetarg=%d, wiredmax=%d", 198 uvmexp.freemin, uvmexp.freetarg, uvmexp.wiredmax, 0); 199 } 200 201 /* 202 * uvm_pageout: the main loop for the pagedaemon 203 */ 204 205 void 206 uvm_pageout(void *arg) 207 { 208 int bufcnt, npages = 0; 209 int extrapages = 0; 210 UVMHIST_FUNC("uvm_pageout"); UVMHIST_CALLED(pdhist); 211 212 UVMHIST_LOG(pdhist,"<starting uvm pagedaemon>", 0, 0, 0, 0); 213 214 /* 215 * ensure correct priority and set paging parameters... 216 */ 217 218 uvm.pagedaemon_proc = curproc; 219 uvm_lock_pageq(); 220 npages = uvmexp.npages; 221 uvmpd_tune(); 222 uvm_unlock_pageq(); 223 224 /* 225 * main loop 226 */ 227 228 for (;;) { 229 simple_lock(&uvm.pagedaemon_lock); 230 231 UVMHIST_LOG(pdhist," <<SLEEPING>>",0,0,0,0); 232 UVM_UNLOCK_AND_WAIT(&uvm.pagedaemon, 233 &uvm.pagedaemon_lock, FALSE, "pgdaemon", 0); 234 uvmexp.pdwoke++; 235 UVMHIST_LOG(pdhist," <<WOKE UP>>",0,0,0,0); 236 237 /* 238 * now lock page queues and recompute inactive count 239 */ 240 241 uvm_lock_pageq(); 242 if (npages != uvmexp.npages || extrapages != uvm_extrapages) { 243 npages = uvmexp.npages; 244 extrapages = uvm_extrapages; 245 uvmpd_tune(); 246 } 247 248 uvmexp.inactarg = UVM_PCTPARAM_APPLY(&uvmexp.inactivepct, 249 uvmexp.active + uvmexp.inactive); 250 if (uvmexp.inactarg <= uvmexp.freetarg) { 251 uvmexp.inactarg = uvmexp.freetarg + 1; 252 } 253 254 /* 255 * Estimate a hint. Note that bufmem are returned to 256 * system only when entire pool page is empty. 257 */ 258 bufcnt = uvmexp.freetarg - uvmexp.free; 259 if (bufcnt < 0) 260 bufcnt = 0; 261 262 UVMHIST_LOG(pdhist," free/ftarg=%d/%d, inact/itarg=%d/%d", 263 uvmexp.free, uvmexp.freetarg, uvmexp.inactive, 264 uvmexp.inactarg); 265 266 /* 267 * scan if needed 268 */ 269 270 if (uvmexp.free + uvmexp.paging < uvmexp.freetarg || 271 uvmexp.inactive < uvmexp.inactarg) { 272 uvmpd_scan(); 273 } 274 275 /* 276 * if there's any free memory to be had, 277 * wake up any waiters. 278 */ 279 280 if (uvmexp.free > uvmexp.reserve_kernel || 281 uvmexp.paging == 0) { 282 wakeup(&uvmexp.free); 283 } 284 285 /* 286 * scan done. unlock page queues (the only lock we are holding) 287 */ 288 289 uvm_unlock_pageq(); 290 291 buf_drain(bufcnt << PAGE_SHIFT); 292 293 /* 294 * drain pool resources now that we're not holding any locks 295 */ 296 297 pool_drain(0); 298 299 /* 300 * free any cached u-areas we don't need 301 */ 302 uvm_uarea_drain(TRUE); 303 304 } 305 /*NOTREACHED*/ 306 } 307 308 309 /* 310 * uvm_aiodone_daemon: main loop for the aiodone daemon. 311 */ 312 313 void 314 uvm_aiodone_daemon(void *arg) 315 { 316 int s, free; 317 struct buf *bp, *nbp; 318 UVMHIST_FUNC("uvm_aiodoned"); UVMHIST_CALLED(pdhist); 319 320 for (;;) { 321 322 /* 323 * carefully attempt to go to sleep (without losing "wakeups"!). 324 * we need splbio because we want to make sure the aio_done list 325 * is totally empty before we go to sleep. 326 */ 327 328 s = splbio(); 329 simple_lock(&uvm.aiodoned_lock); 330 if (TAILQ_FIRST(&uvm.aio_done) == NULL) { 331 UVMHIST_LOG(pdhist," <<SLEEPING>>",0,0,0,0); 332 UVM_UNLOCK_AND_WAIT(&uvm.aiodoned, 333 &uvm.aiodoned_lock, FALSE, "aiodoned", 0); 334 UVMHIST_LOG(pdhist," <<WOKE UP>>",0,0,0,0); 335 336 /* relock aiodoned_lock, still at splbio */ 337 simple_lock(&uvm.aiodoned_lock); 338 } 339 340 /* 341 * check for done aio structures 342 */ 343 344 bp = TAILQ_FIRST(&uvm.aio_done); 345 if (bp) { 346 TAILQ_INIT(&uvm.aio_done); 347 } 348 349 simple_unlock(&uvm.aiodoned_lock); 350 splx(s); 351 352 /* 353 * process each i/o that's done. 354 */ 355 356 free = uvmexp.free; 357 while (bp != NULL) { 358 nbp = TAILQ_NEXT(bp, b_freelist); 359 (*bp->b_iodone)(bp); 360 bp = nbp; 361 } 362 if (free <= uvmexp.reserve_kernel) { 363 s = uvm_lock_fpageq(); 364 wakeup(&uvm.pagedaemon); 365 uvm_unlock_fpageq(s); 366 } else { 367 simple_lock(&uvm.pagedaemon_lock); 368 wakeup(&uvmexp.free); 369 simple_unlock(&uvm.pagedaemon_lock); 370 } 371 } 372 } 373 374 /* 375 * uvmpd_scan_inactive: scan an inactive list for pages to clean or free. 376 * 377 * => called with page queues locked 378 * => we work on meeting our free target by converting inactive pages 379 * into free pages. 380 * => we handle the building of swap-backed clusters 381 * => we return TRUE if we are exiting because we met our target 382 */ 383 384 static void 385 uvmpd_scan_inactive(struct pglist *pglst) 386 { 387 struct vm_page *p, *nextpg = NULL; /* Quell compiler warning */ 388 struct uvm_object *uobj; 389 struct vm_anon *anon; 390 #if defined(VMSWAP) 391 struct vm_page *swpps[round_page(MAXPHYS) >> PAGE_SHIFT]; 392 int error; 393 int result; 394 #endif /* defined(VMSWAP) */ 395 struct simplelock *slock; 396 int swnpages, swcpages; 397 int swslot; 398 int dirtyreacts, t; 399 boolean_t anonunder, fileunder, execunder; 400 boolean_t anonover, fileover, execover; 401 boolean_t anonreact, filereact, execreact; 402 UVMHIST_FUNC("uvmpd_scan_inactive"); UVMHIST_CALLED(pdhist); 403 404 /* 405 * swslot is non-zero if we are building a swap cluster. we want 406 * to stay in the loop while we have a page to scan or we have 407 * a swap-cluster to build. 408 */ 409 410 swslot = 0; 411 swnpages = swcpages = 0; 412 dirtyreacts = 0; 413 414 /* 415 * decide which types of pages we want to reactivate instead of freeing 416 * to keep usage within the minimum and maximum usage limits. 417 */ 418 419 t = uvmexp.active + uvmexp.inactive + uvmexp.free; 420 anonunder = (uvmexp.anonpages <= (t * uvmexp.anonmin) >> 8); 421 fileunder = (uvmexp.filepages <= (t * uvmexp.filemin) >> 8); 422 execunder = (uvmexp.execpages <= (t * uvmexp.execmin) >> 8); 423 anonover = uvmexp.anonpages > ((t * uvmexp.anonmax) >> 8); 424 fileover = uvmexp.filepages > ((t * uvmexp.filemax) >> 8); 425 execover = uvmexp.execpages > ((t * uvmexp.execmax) >> 8); 426 anonreact = anonunder || (!anonover && (fileover || execover)); 427 filereact = fileunder || (!fileover && (anonover || execover)); 428 execreact = execunder || (!execover && (anonover || fileover)); 429 if (filereact && execreact && (anonreact || uvm_swapisfull())) { 430 anonreact = filereact = execreact = FALSE; 431 } 432 #if !defined(VMSWAP) 433 /* 434 * XXX no point to put swap-backed pages on the page queue. 435 */ 436 437 anonreact = TRUE; 438 #endif /* !defined(VMSWAP) */ 439 for (p = TAILQ_FIRST(pglst); p != NULL || swslot != 0; p = nextpg) { 440 uobj = NULL; 441 anon = NULL; 442 if (p) { 443 444 /* 445 * see if we've met the free target. 446 */ 447 448 if (uvmexp.free + uvmexp.paging >= 449 uvmexp.freetarg << 2 || 450 dirtyreacts == UVMPD_NUMDIRTYREACTS) { 451 UVMHIST_LOG(pdhist," met free target: " 452 "exit loop", 0, 0, 0, 0); 453 454 if (swslot == 0) { 455 /* exit now if no swap-i/o pending */ 456 break; 457 } 458 459 /* set p to null to signal final swap i/o */ 460 p = NULL; 461 nextpg = NULL; 462 } 463 } 464 if (p) { /* if (we have a new page to consider) */ 465 466 /* 467 * we are below target and have a new page to consider. 468 */ 469 470 uvmexp.pdscans++; 471 nextpg = TAILQ_NEXT(p, pageq); 472 473 /* 474 * move referenced pages back to active queue and 475 * skip to next page. 476 */ 477 478 if (pmap_is_referenced(p)) { 479 uvm_pageactivate(p); 480 uvmexp.pdreact++; 481 continue; 482 } 483 anon = p->uanon; 484 uobj = p->uobject; 485 486 /* 487 * enforce the minimum thresholds on different 488 * types of memory usage. if reusing the current 489 * page would reduce that type of usage below its 490 * minimum, reactivate the page instead and move 491 * on to the next page. 492 */ 493 494 if (uobj && UVM_OBJ_IS_VTEXT(uobj) && execreact) { 495 uvm_pageactivate(p); 496 uvmexp.pdreexec++; 497 continue; 498 } 499 if (uobj && UVM_OBJ_IS_VNODE(uobj) && 500 !UVM_OBJ_IS_VTEXT(uobj) && filereact) { 501 uvm_pageactivate(p); 502 uvmexp.pdrefile++; 503 continue; 504 } 505 if ((anon || UVM_OBJ_IS_AOBJ(uobj)) && anonreact) { 506 uvm_pageactivate(p); 507 uvmexp.pdreanon++; 508 continue; 509 } 510 511 /* 512 * first we attempt to lock the object that this page 513 * belongs to. if our attempt fails we skip on to 514 * the next page (no harm done). it is important to 515 * "try" locking the object as we are locking in the 516 * wrong order (pageq -> object) and we don't want to 517 * deadlock. 518 * 519 * the only time we expect to see an ownerless page 520 * (i.e. a page with no uobject and !PQ_ANON) is if an 521 * anon has loaned a page from a uvm_object and the 522 * uvm_object has dropped the ownership. in that 523 * case, the anon can "take over" the loaned page 524 * and make it its own. 525 */ 526 527 /* does the page belong to an object? */ 528 if (uobj != NULL) { 529 slock = &uobj->vmobjlock; 530 if (!simple_lock_try(slock)) { 531 continue; 532 } 533 if (p->flags & PG_BUSY) { 534 simple_unlock(slock); 535 uvmexp.pdbusy++; 536 continue; 537 } 538 uvmexp.pdobscan++; 539 } else { 540 #if defined(VMSWAP) 541 KASSERT(anon != NULL); 542 slock = &anon->an_lock; 543 if (!simple_lock_try(slock)) { 544 continue; 545 } 546 547 /* 548 * set PQ_ANON if it isn't set already. 549 */ 550 551 if ((p->pqflags & PQ_ANON) == 0) { 552 KASSERT(p->loan_count > 0); 553 p->loan_count--; 554 p->pqflags |= PQ_ANON; 555 /* anon now owns it */ 556 } 557 if (p->flags & PG_BUSY) { 558 simple_unlock(slock); 559 uvmexp.pdbusy++; 560 continue; 561 } 562 uvmexp.pdanscan++; 563 #else /* defined(VMSWAP) */ 564 panic("%s: anon", __func__); 565 #endif /* defined(VMSWAP) */ 566 } 567 568 569 /* 570 * we now have the object and the page queues locked. 571 * if the page is not swap-backed, call the object's 572 * pager to flush and free the page. 573 */ 574 575 #if defined(READAHEAD_STATS) 576 if ((p->flags & PG_SPECULATIVE) != 0) { 577 p->flags &= ~PG_SPECULATIVE; 578 uvm_ra_miss.ev_count++; 579 } 580 #endif /* defined(READAHEAD_STATS) */ 581 582 if ((p->pqflags & PQ_SWAPBACKED) == 0) { 583 uvm_unlock_pageq(); 584 (void) (uobj->pgops->pgo_put)(uobj, p->offset, 585 p->offset + PAGE_SIZE, 586 PGO_CLEANIT|PGO_FREE); 587 uvm_lock_pageq(); 588 if (nextpg && 589 (nextpg->pqflags & PQ_INACTIVE) == 0) { 590 nextpg = TAILQ_FIRST(pglst); 591 } 592 continue; 593 } 594 595 #if defined(VMSWAP) 596 /* 597 * the page is swap-backed. remove all the permissions 598 * from the page so we can sync the modified info 599 * without any race conditions. if the page is clean 600 * we can free it now and continue. 601 */ 602 603 pmap_page_protect(p, VM_PROT_NONE); 604 if ((p->flags & PG_CLEAN) && pmap_clear_modify(p)) { 605 p->flags &= ~(PG_CLEAN); 606 } 607 if (p->flags & PG_CLEAN) { 608 int slot; 609 int pageidx; 610 611 pageidx = p->offset >> PAGE_SHIFT; 612 uvm_pagefree(p); 613 uvmexp.pdfreed++; 614 615 /* 616 * for anons, we need to remove the page 617 * from the anon ourselves. for aobjs, 618 * pagefree did that for us. 619 */ 620 621 if (anon) { 622 KASSERT(anon->an_swslot != 0); 623 anon->an_page = NULL; 624 slot = anon->an_swslot; 625 } else { 626 slot = uao_find_swslot(uobj, pageidx); 627 } 628 simple_unlock(slock); 629 630 if (slot > 0) { 631 /* this page is now only in swap. */ 632 simple_lock(&uvm.swap_data_lock); 633 KASSERT(uvmexp.swpgonly < 634 uvmexp.swpginuse); 635 uvmexp.swpgonly++; 636 simple_unlock(&uvm.swap_data_lock); 637 } 638 continue; 639 } 640 641 /* 642 * this page is dirty, skip it if we'll have met our 643 * free target when all the current pageouts complete. 644 */ 645 646 if (uvmexp.free + uvmexp.paging > 647 uvmexp.freetarg << 2) { 648 simple_unlock(slock); 649 continue; 650 } 651 652 /* 653 * free any swap space allocated to the page since 654 * we'll have to write it again with its new data. 655 */ 656 657 if ((p->pqflags & PQ_ANON) && anon->an_swslot) { 658 uvm_swap_free(anon->an_swslot, 1); 659 anon->an_swslot = 0; 660 } else if (p->pqflags & PQ_AOBJ) { 661 uao_dropswap(uobj, p->offset >> PAGE_SHIFT); 662 } 663 664 /* 665 * if all pages in swap are only in swap, 666 * the swap space is full and we can't page out 667 * any more swap-backed pages. reactivate this page 668 * so that we eventually cycle all pages through 669 * the inactive queue. 670 */ 671 672 if (uvm_swapisfull()) { 673 dirtyreacts++; 674 uvm_pageactivate(p); 675 simple_unlock(slock); 676 continue; 677 } 678 679 /* 680 * start new swap pageout cluster (if necessary). 681 */ 682 683 if (swslot == 0) { 684 /* Even with strange MAXPHYS, the shift 685 implicitly rounds down to a page. */ 686 swnpages = MAXPHYS >> PAGE_SHIFT; 687 swslot = uvm_swap_alloc(&swnpages, TRUE); 688 if (swslot == 0) { 689 simple_unlock(slock); 690 continue; 691 } 692 swcpages = 0; 693 } 694 695 /* 696 * at this point, we're definitely going reuse this 697 * page. mark the page busy and delayed-free. 698 * we should remove the page from the page queues 699 * so we don't ever look at it again. 700 * adjust counters and such. 701 */ 702 703 p->flags |= PG_BUSY; 704 UVM_PAGE_OWN(p, "scan_inactive"); 705 706 p->flags |= PG_PAGEOUT; 707 uvmexp.paging++; 708 uvm_pagedequeue(p); 709 710 uvmexp.pgswapout++; 711 712 /* 713 * add the new page to the cluster. 714 */ 715 716 if (anon) { 717 anon->an_swslot = swslot + swcpages; 718 simple_unlock(slock); 719 } else { 720 result = uao_set_swslot(uobj, 721 p->offset >> PAGE_SHIFT, swslot + swcpages); 722 if (result == -1) { 723 p->flags &= ~(PG_BUSY|PG_PAGEOUT); 724 UVM_PAGE_OWN(p, NULL); 725 uvmexp.paging--; 726 uvm_pageactivate(p); 727 simple_unlock(slock); 728 continue; 729 } 730 simple_unlock(slock); 731 } 732 swpps[swcpages] = p; 733 swcpages++; 734 735 /* 736 * if the cluster isn't full, look for more pages 737 * before starting the i/o. 738 */ 739 740 if (swcpages < swnpages) { 741 continue; 742 } 743 #else /* defined(VMSWAP) */ 744 panic("%s: swap-backed", __func__); 745 #endif /* defined(VMSWAP) */ 746 747 } 748 749 #if defined(VMSWAP) 750 /* 751 * if this is the final pageout we could have a few 752 * unused swap blocks. if so, free them now. 753 */ 754 755 if (swcpages < swnpages) { 756 uvm_swap_free(swslot + swcpages, (swnpages - swcpages)); 757 } 758 759 /* 760 * now start the pageout. 761 */ 762 763 uvm_unlock_pageq(); 764 uvmexp.pdpageouts++; 765 error = uvm_swap_put(swslot, swpps, swcpages, 0); 766 KASSERT(error == 0); 767 uvm_lock_pageq(); 768 769 /* 770 * zero swslot to indicate that we are 771 * no longer building a swap-backed cluster. 772 */ 773 774 swslot = 0; 775 776 /* 777 * the pageout is in progress. bump counters and set up 778 * for the next loop. 779 */ 780 781 uvmexp.pdpending++; 782 if (nextpg && (nextpg->pqflags & PQ_INACTIVE) == 0) { 783 nextpg = TAILQ_FIRST(pglst); 784 } 785 #endif /* defined(VMSWAP) */ 786 } 787 } 788 789 /* 790 * uvmpd_scan: scan the page queues and attempt to meet our targets. 791 * 792 * => called with pageq's locked 793 */ 794 795 static void 796 uvmpd_scan(void) 797 { 798 int inactive_shortage, swap_shortage, pages_freed; 799 struct vm_page *p, *nextpg; 800 struct uvm_object *uobj; 801 struct vm_anon *anon; 802 struct simplelock *slock; 803 UVMHIST_FUNC("uvmpd_scan"); UVMHIST_CALLED(pdhist); 804 805 uvmexp.pdrevs++; 806 uobj = NULL; 807 anon = NULL; 808 809 #ifndef __SWAP_BROKEN 810 811 /* 812 * swap out some processes if we are below our free target. 813 * we need to unlock the page queues for this. 814 */ 815 816 if (uvmexp.free < uvmexp.freetarg && uvmexp.nswapdev != 0) { 817 uvmexp.pdswout++; 818 UVMHIST_LOG(pdhist," free %d < target %d: swapout", 819 uvmexp.free, uvmexp.freetarg, 0, 0); 820 uvm_unlock_pageq(); 821 uvm_swapout_threads(); 822 uvm_lock_pageq(); 823 824 } 825 #endif 826 827 /* 828 * now we want to work on meeting our targets. first we work on our 829 * free target by converting inactive pages into free pages. then 830 * we work on meeting our inactive target by converting active pages 831 * to inactive ones. 832 */ 833 834 UVMHIST_LOG(pdhist, " starting 'free' loop",0,0,0,0); 835 836 pages_freed = uvmexp.pdfreed; 837 uvmpd_scan_inactive(&uvm.page_inactive); 838 pages_freed = uvmexp.pdfreed - pages_freed; 839 840 /* 841 * we have done the scan to get free pages. now we work on meeting 842 * our inactive target. 843 */ 844 845 inactive_shortage = uvmexp.inactarg - uvmexp.inactive; 846 847 /* 848 * detect if we're not going to be able to page anything out 849 * until we free some swap resources from active pages. 850 */ 851 852 swap_shortage = 0; 853 if (uvmexp.free < uvmexp.freetarg && 854 uvmexp.swpginuse >= uvmexp.swpgavail && 855 !uvm_swapisfull() && 856 pages_freed == 0) { 857 swap_shortage = uvmexp.freetarg - uvmexp.free; 858 } 859 860 UVMHIST_LOG(pdhist, " loop 2: inactive_shortage=%d swap_shortage=%d", 861 inactive_shortage, swap_shortage,0,0); 862 for (p = TAILQ_FIRST(&uvm.page_active); 863 p != NULL && (inactive_shortage > 0 || swap_shortage > 0); 864 p = nextpg) { 865 nextpg = TAILQ_NEXT(p, pageq); 866 if (p->flags & PG_BUSY) { 867 continue; 868 } 869 870 /* 871 * lock the page's owner. 872 */ 873 874 if (p->uobject != NULL) { 875 uobj = p->uobject; 876 slock = &uobj->vmobjlock; 877 if (!simple_lock_try(slock)) { 878 continue; 879 } 880 } else { 881 anon = p->uanon; 882 KASSERT(anon != NULL); 883 slock = &anon->an_lock; 884 if (!simple_lock_try(slock)) { 885 continue; 886 } 887 888 /* take over the page? */ 889 if ((p->pqflags & PQ_ANON) == 0) { 890 KASSERT(p->loan_count > 0); 891 p->loan_count--; 892 p->pqflags |= PQ_ANON; 893 } 894 } 895 896 /* 897 * skip this page if it's busy. 898 */ 899 900 if ((p->flags & PG_BUSY) != 0) { 901 simple_unlock(slock); 902 continue; 903 } 904 905 #if defined(VMSWAP) 906 /* 907 * if there's a shortage of swap, free any swap allocated 908 * to this page so that other pages can be paged out. 909 */ 910 911 if (swap_shortage > 0) { 912 if ((p->pqflags & PQ_ANON) && anon->an_swslot) { 913 uvm_swap_free(anon->an_swslot, 1); 914 anon->an_swslot = 0; 915 p->flags &= ~PG_CLEAN; 916 swap_shortage--; 917 } else if (p->pqflags & PQ_AOBJ) { 918 int slot = uao_set_swslot(uobj, 919 p->offset >> PAGE_SHIFT, 0); 920 if (slot) { 921 uvm_swap_free(slot, 1); 922 p->flags &= ~PG_CLEAN; 923 swap_shortage--; 924 } 925 } 926 } 927 #endif /* defined(VMSWAP) */ 928 929 /* 930 * if there's a shortage of inactive pages, deactivate. 931 */ 932 933 if (inactive_shortage > 0) { 934 /* no need to check wire_count as pg is "active" */ 935 pmap_clear_reference(p); 936 uvm_pagedeactivate(p); 937 uvmexp.pddeact++; 938 inactive_shortage--; 939 } 940 941 /* 942 * we're done with this page. 943 */ 944 945 simple_unlock(slock); 946 } 947 } 948 949 /* 950 * uvm_reclaimable: decide whether to wait for pagedaemon. 951 * 952 * => return TRUE if it seems to be worth to do uvm_wait. 953 * 954 * XXX should be tunable. 955 * XXX should consider pools, etc? 956 */ 957 958 boolean_t 959 uvm_reclaimable(void) 960 { 961 int filepages; 962 963 /* 964 * if swap is not full, no problem. 965 */ 966 967 if (!uvm_swapisfull()) { 968 return TRUE; 969 } 970 971 /* 972 * file-backed pages can be reclaimed even when swap is full. 973 * if we have more than 1/16 of pageable memory or 5MB, try to reclaim. 974 * 975 * XXX assume the worst case, ie. all wired pages are file-backed. 976 * 977 * XXX should consider about other reclaimable memory. 978 * XXX ie. pools, traditional buffer cache. 979 */ 980 981 filepages = uvmexp.filepages + uvmexp.execpages - uvmexp.wired; 982 if (filepages >= MIN((uvmexp.active + uvmexp.inactive) >> 4, 983 5 * 1024 * 1024 >> PAGE_SHIFT)) { 984 return TRUE; 985 } 986 987 /* 988 * kill the process, fail allocation, etc.. 989 */ 990 991 return FALSE; 992 } 993