1 /* $NetBSD: uvm_pdaemon.c,v 1.31 2001/03/10 22:46:50 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 static void uvmpd_scan __P((void)); 100 static boolean_t uvmpd_scan_inactive __P((struct pglist *)); 101 static 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) { 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 static void 164 uvmpd_tune() 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 (void) spl0(); 208 uvm_lock_pageq(); 209 npages = uvmexp.npages; 210 uvmpd_tune(); 211 uvm_unlock_pageq(); 212 213 /* 214 * main loop 215 */ 216 217 for (;;) { 218 simple_lock(&uvm.pagedaemon_lock); 219 220 UVMHIST_LOG(pdhist," <<SLEEPING>>",0,0,0,0); 221 UVM_UNLOCK_AND_WAIT(&uvm.pagedaemon, 222 &uvm.pagedaemon_lock, FALSE, "pgdaemon", 0); 223 uvmexp.pdwoke++; 224 UVMHIST_LOG(pdhist," <<WOKE UP>>",0,0,0,0); 225 226 /* drain pool resources */ 227 pool_drain(0); 228 229 /* 230 * now lock page queues and recompute inactive count 231 */ 232 233 uvm_lock_pageq(); 234 if (npages != uvmexp.npages) { /* check for new pages? */ 235 npages = uvmexp.npages; 236 uvmpd_tune(); 237 } 238 239 uvmexp.inactarg = (uvmexp.active + uvmexp.inactive) / 3; 240 if (uvmexp.inactarg <= uvmexp.freetarg) { 241 uvmexp.inactarg = uvmexp.freetarg + 1; 242 } 243 244 UVMHIST_LOG(pdhist," free/ftarg=%d/%d, inact/itarg=%d/%d", 245 uvmexp.free, uvmexp.freetarg, uvmexp.inactive, 246 uvmexp.inactarg); 247 248 /* 249 * scan if needed 250 */ 251 252 if (uvmexp.free + uvmexp.paging < uvmexp.freetarg || 253 uvmexp.inactive < uvmexp.inactarg) { 254 uvmpd_scan(); 255 } 256 257 /* 258 * if there's any free memory to be had, 259 * wake up any waiters. 260 */ 261 262 if (uvmexp.free > uvmexp.reserve_kernel || 263 uvmexp.paging == 0) { 264 wakeup(&uvmexp.free); 265 } 266 267 /* 268 * scan done. unlock page queues (the only lock we are holding) 269 */ 270 271 uvm_unlock_pageq(); 272 } 273 /*NOTREACHED*/ 274 } 275 276 277 /* 278 * uvm_aiodone_daemon: main loop for the aiodone daemon. 279 */ 280 281 void 282 uvm_aiodone_daemon(void *arg) 283 { 284 int s, free; 285 struct buf *bp, *nbp; 286 UVMHIST_FUNC("uvm_aiodoned"); UVMHIST_CALLED(pdhist); 287 288 for (;;) { 289 290 /* 291 * carefully attempt to go to sleep (without losing "wakeups"!). 292 * we need splbio because we want to make sure the aio_done list 293 * is totally empty before we go to sleep. 294 */ 295 296 s = splbio(); 297 simple_lock(&uvm.aiodoned_lock); 298 if (TAILQ_FIRST(&uvm.aio_done) == NULL) { 299 UVMHIST_LOG(pdhist," <<SLEEPING>>",0,0,0,0); 300 UVM_UNLOCK_AND_WAIT(&uvm.aiodoned, 301 &uvm.aiodoned_lock, FALSE, "aiodoned", 0); 302 UVMHIST_LOG(pdhist," <<WOKE UP>>",0,0,0,0); 303 304 /* relock aiodoned_lock, still at splbio */ 305 simple_lock(&uvm.aiodoned_lock); 306 } 307 308 /* 309 * check for done aio structures 310 */ 311 312 bp = TAILQ_FIRST(&uvm.aio_done); 313 if (bp) { 314 TAILQ_INIT(&uvm.aio_done); 315 } 316 317 simple_unlock(&uvm.aiodoned_lock); 318 splx(s); 319 320 /* 321 * process each i/o that's done. 322 */ 323 324 free = uvmexp.free; 325 while (bp != NULL) { 326 if (bp->b_flags & B_PDAEMON) { 327 uvmexp.paging -= bp->b_bufsize >> PAGE_SHIFT; 328 } 329 nbp = TAILQ_NEXT(bp, b_freelist); 330 (*bp->b_iodone)(bp); 331 bp = nbp; 332 } 333 if (free <= uvmexp.reserve_kernel) { 334 s = uvm_lock_fpageq(); 335 wakeup(&uvm.pagedaemon); 336 uvm_unlock_fpageq(s); 337 } else { 338 simple_lock(&uvm.pagedaemon_lock); 339 wakeup(&uvmexp.free); 340 simple_unlock(&uvm.pagedaemon_lock); 341 } 342 } 343 } 344 345 346 347 /* 348 * uvmpd_scan_inactive: scan an inactive list for pages to clean or free. 349 * 350 * => called with page queues locked 351 * => we work on meeting our free target by converting inactive pages 352 * into free pages. 353 * => we handle the building of swap-backed clusters 354 * => we return TRUE if we are exiting because we met our target 355 */ 356 357 static boolean_t 358 uvmpd_scan_inactive(pglst) 359 struct pglist *pglst; 360 { 361 boolean_t retval = FALSE; /* assume we haven't hit target */ 362 int s, free, result; 363 struct vm_page *p, *nextpg; 364 struct uvm_object *uobj; 365 struct vm_page *pps[MAXBSIZE >> PAGE_SHIFT], **ppsp; 366 int npages; 367 struct vm_page *swpps[MAXBSIZE >> PAGE_SHIFT]; /* XXX: see below */ 368 int swnpages, swcpages; /* XXX: see below */ 369 int swslot; 370 struct vm_anon *anon; 371 boolean_t swap_backed; 372 vaddr_t start; 373 int dirtyreacts, t; 374 UVMHIST_FUNC("uvmpd_scan_inactive"); UVMHIST_CALLED(pdhist); 375 376 /* 377 * note: we currently keep swap-backed pages on a seperate inactive 378 * list from object-backed pages. however, merging the two lists 379 * back together again hasn't been ruled out. thus, we keep our 380 * swap cluster in "swpps" rather than in pps (allows us to mix 381 * clustering types in the event of a mixed inactive queue). 382 */ 383 384 /* 385 * swslot is non-zero if we are building a swap cluster. we want 386 * to stay in the loop while we have a page to scan or we have 387 * a swap-cluster to build. 388 */ 389 390 swslot = 0; 391 swnpages = swcpages = 0; 392 free = 0; 393 dirtyreacts = 0; 394 395 for (p = TAILQ_FIRST(pglst); p != NULL || swslot != 0; p = nextpg) { 396 397 /* 398 * note that p can be NULL iff we have traversed the whole 399 * list and need to do one final swap-backed clustered pageout. 400 */ 401 402 uobj = NULL; 403 anon = NULL; 404 405 if (p) { 406 407 /* 408 * update our copy of "free" and see if we've met 409 * our target 410 */ 411 412 s = uvm_lock_fpageq(); 413 free = uvmexp.free; 414 uvm_unlock_fpageq(s); 415 416 if (free + uvmexp.paging >= uvmexp.freetarg << 2 || 417 dirtyreacts == UVMPD_NUMDIRTYREACTS) { 418 UVMHIST_LOG(pdhist," met free target: " 419 "exit loop", 0, 0, 0, 0); 420 retval = TRUE; 421 422 if (swslot == 0) { 423 /* exit now if no swap-i/o pending */ 424 break; 425 } 426 427 /* set p to null to signal final swap i/o */ 428 p = NULL; 429 } 430 } 431 432 if (p) { /* if (we have a new page to consider) */ 433 434 /* 435 * we are below target and have a new page to consider. 436 */ 437 uvmexp.pdscans++; 438 nextpg = TAILQ_NEXT(p, pageq); 439 440 /* 441 * move referenced pages back to active queue and 442 * skip to next page. 443 */ 444 445 if (pmap_is_referenced(p)) { 446 uvm_pageactivate(p); 447 uvmexp.pdreact++; 448 continue; 449 } 450 451 /* 452 * enforce the minimum thresholds on different 453 * types of memory usage. if reusing the current 454 * page would reduce that type of usage below its 455 * minimum, reactivate the page instead and move 456 * on to the next page. 457 */ 458 459 t = uvmexp.active + uvmexp.inactive + uvmexp.free; 460 if (p->uanon && 461 uvmexp.anonpages <= (t * uvmexp.anonmin) >> 8) { 462 uvm_pageactivate(p); 463 uvmexp.pdreanon++; 464 continue; 465 } 466 if (p->uobject && UVM_OBJ_IS_VTEXT(p->uobject) && 467 uvmexp.vtextpages <= (t * uvmexp.vtextmin) >> 8) { 468 uvm_pageactivate(p); 469 uvmexp.pdrevtext++; 470 continue; 471 } 472 if (p->uobject && UVM_OBJ_IS_VNODE(p->uobject) && 473 !UVM_OBJ_IS_VTEXT(p->uobject) && 474 uvmexp.vnodepages <= (t * uvmexp.vnodemin) >> 8) { 475 uvm_pageactivate(p); 476 uvmexp.pdrevnode++; 477 continue; 478 } 479 480 /* 481 * first we attempt to lock the object that this page 482 * belongs to. if our attempt fails we skip on to 483 * the next page (no harm done). it is important to 484 * "try" locking the object as we are locking in the 485 * wrong order (pageq -> object) and we don't want to 486 * deadlock. 487 * 488 * the only time we expect to see an ownerless page 489 * (i.e. a page with no uobject and !PQ_ANON) is if an 490 * anon has loaned a page from a uvm_object and the 491 * uvm_object has dropped the ownership. in that 492 * case, the anon can "take over" the loaned page 493 * and make it its own. 494 */ 495 496 /* is page part of an anon or ownerless ? */ 497 if ((p->pqflags & PQ_ANON) || p->uobject == NULL) { 498 anon = p->uanon; 499 KASSERT(anon != NULL); 500 if (!simple_lock_try(&anon->an_lock)) { 501 /* lock failed, skip this page */ 502 continue; 503 } 504 505 /* 506 * if the page is ownerless, claim it in the 507 * name of "anon"! 508 */ 509 510 if ((p->pqflags & PQ_ANON) == 0) { 511 KASSERT(p->loan_count > 0); 512 p->loan_count--; 513 p->pqflags |= PQ_ANON; 514 /* anon now owns it */ 515 } 516 if (p->flags & PG_BUSY) { 517 simple_unlock(&anon->an_lock); 518 uvmexp.pdbusy++; 519 /* someone else owns page, skip it */ 520 continue; 521 } 522 uvmexp.pdanscan++; 523 } else { 524 uobj = p->uobject; 525 KASSERT(uobj != NULL); 526 if (!simple_lock_try(&uobj->vmobjlock)) { 527 /* lock failed, skip this page */ 528 continue; 529 } 530 if (p->flags & PG_BUSY) { 531 simple_unlock(&uobj->vmobjlock); 532 uvmexp.pdbusy++; 533 /* someone else owns page, skip it */ 534 continue; 535 } 536 uvmexp.pdobscan++; 537 } 538 539 /* 540 * we now have the object and the page queues locked. 541 * the page is not busy. remove all the permissions 542 * from the page so we can sync the modified info 543 * without any race conditions. if the page is clean 544 * we can free it now and continue. 545 */ 546 547 pmap_page_protect(p, VM_PROT_NONE); 548 if ((p->flags & PG_CLEAN) != 0 && pmap_is_modified(p)) { 549 p->flags &= ~PG_CLEAN; 550 } 551 552 if (p->flags & PG_CLEAN) { 553 if (p->pqflags & PQ_SWAPBACKED) { 554 /* this page now lives only in swap */ 555 simple_lock(&uvm.swap_data_lock); 556 uvmexp.swpgonly++; 557 simple_unlock(&uvm.swap_data_lock); 558 } 559 560 uvm_pagefree(p); 561 uvmexp.pdfreed++; 562 563 if (anon) { 564 565 /* 566 * an anonymous page can only be clean 567 * if it has backing store assigned. 568 */ 569 570 KASSERT(anon->an_swslot != 0); 571 572 /* remove from object */ 573 anon->u.an_page = NULL; 574 simple_unlock(&anon->an_lock); 575 } else { 576 /* pagefree has already removed the 577 * page from the object */ 578 simple_unlock(&uobj->vmobjlock); 579 } 580 continue; 581 } 582 583 /* 584 * this page is dirty, skip it if we'll have met our 585 * free target when all the current pageouts complete. 586 */ 587 588 if (free + uvmexp.paging > uvmexp.freetarg << 2) { 589 if (anon) { 590 simple_unlock(&anon->an_lock); 591 } else { 592 simple_unlock(&uobj->vmobjlock); 593 } 594 continue; 595 } 596 597 /* 598 * this page is dirty, but we can't page it out 599 * since all pages in swap are only in swap. 600 * reactivate it so that we eventually cycle 601 * all pages thru the inactive queue. 602 */ 603 604 KASSERT(uvmexp.swpgonly <= uvmexp.swpages); 605 if ((p->pqflags & PQ_SWAPBACKED) && 606 uvmexp.swpgonly == uvmexp.swpages) { 607 dirtyreacts++; 608 uvm_pageactivate(p); 609 if (anon) { 610 simple_unlock(&anon->an_lock); 611 } else { 612 simple_unlock(&uobj->vmobjlock); 613 } 614 continue; 615 } 616 617 /* 618 * if the page is swap-backed and dirty and swap space 619 * is full, free any swap allocated to the page 620 * so that other pages can be paged out. 621 */ 622 623 KASSERT(uvmexp.swpginuse <= uvmexp.swpages); 624 if ((p->pqflags & PQ_SWAPBACKED) && 625 uvmexp.swpginuse == uvmexp.swpages) { 626 627 if ((p->pqflags & PQ_ANON) && 628 p->uanon->an_swslot) { 629 uvm_swap_free(p->uanon->an_swslot, 1); 630 p->uanon->an_swslot = 0; 631 } 632 if (p->pqflags & PQ_AOBJ) { 633 uao_dropswap(p->uobject, 634 p->offset >> PAGE_SHIFT); 635 } 636 } 637 638 /* 639 * the page we are looking at is dirty. we must 640 * clean it before it can be freed. to do this we 641 * first mark the page busy so that no one else will 642 * touch the page. 643 */ 644 645 swap_backed = ((p->pqflags & PQ_SWAPBACKED) != 0); 646 p->flags |= PG_BUSY; /* now we own it */ 647 UVM_PAGE_OWN(p, "scan_inactive"); 648 uvmexp.pgswapout++; 649 650 /* 651 * for swap-backed pages we need to (re)allocate 652 * swap space. 653 */ 654 655 if (swap_backed) { 656 657 /* 658 * free old swap slot (if any) 659 */ 660 661 if (anon) { 662 if (anon->an_swslot) { 663 uvm_swap_free(anon->an_swslot, 664 1); 665 anon->an_swslot = 0; 666 } 667 } else { 668 uao_dropswap(uobj, 669 p->offset >> PAGE_SHIFT); 670 } 671 672 /* 673 * start new cluster (if necessary) 674 */ 675 676 if (swslot == 0) { 677 swnpages = MAXBSIZE >> PAGE_SHIFT; 678 swslot = uvm_swap_alloc(&swnpages, 679 TRUE); 680 if (swslot == 0) { 681 /* no swap? give up! */ 682 p->flags &= ~PG_BUSY; 683 UVM_PAGE_OWN(p, NULL); 684 if (anon) 685 simple_unlock( 686 &anon->an_lock); 687 else 688 simple_unlock( 689 &uobj->vmobjlock); 690 continue; 691 } 692 swcpages = 0; /* cluster is empty */ 693 } 694 695 /* 696 * add block to cluster 697 */ 698 699 swpps[swcpages] = p; 700 if (anon) 701 anon->an_swslot = swslot + swcpages; 702 else 703 uao_set_swslot(uobj, 704 p->offset >> PAGE_SHIFT, 705 swslot + swcpages); 706 swcpages++; 707 } 708 } else { 709 710 /* if p == NULL we must be doing a last swap i/o */ 711 swap_backed = TRUE; 712 } 713 714 /* 715 * now consider doing the pageout. 716 * 717 * for swap-backed pages, we do the pageout if we have either 718 * filled the cluster (in which case (swnpages == swcpages) or 719 * run out of pages (p == NULL). 720 * 721 * for object pages, we always do the pageout. 722 */ 723 724 if (swap_backed) { 725 if (p) { /* if we just added a page to cluster */ 726 if (anon) 727 simple_unlock(&anon->an_lock); 728 else 729 simple_unlock(&uobj->vmobjlock); 730 731 /* cluster not full yet? */ 732 if (swcpages < swnpages) 733 continue; 734 } 735 736 /* starting I/O now... set up for it */ 737 npages = swcpages; 738 ppsp = swpps; 739 /* for swap-backed pages only */ 740 start = (vaddr_t) swslot; 741 742 /* if this is final pageout we could have a few 743 * extra swap blocks */ 744 if (swcpages < swnpages) { 745 uvm_swap_free(swslot + swcpages, 746 (swnpages - swcpages)); 747 } 748 } else { 749 /* normal object pageout */ 750 ppsp = pps; 751 npages = sizeof(pps) / sizeof(struct vm_page *); 752 /* not looked at because PGO_ALLPAGES is set */ 753 start = 0; 754 } 755 756 /* 757 * now do the pageout. 758 * 759 * for swap_backed pages we have already built the cluster. 760 * for !swap_backed pages, uvm_pager_put will call the object's 761 * "make put cluster" function to build a cluster on our behalf. 762 * 763 * we pass the PGO_PDFREECLUST flag to uvm_pager_put to instruct 764 * it to free the cluster pages for us on a successful I/O (it 765 * always does this for un-successful I/O requests). this 766 * allows us to do clustered pageout without having to deal 767 * with cluster pages at this level. 768 * 769 * note locking semantics of uvm_pager_put with PGO_PDFREECLUST: 770 * IN: locked: uobj (if !swap_backed), page queues 771 * OUT:!locked: pageqs, uobj 772 */ 773 774 /* locked: uobj (if !swap_backed), page queues */ 775 uvmexp.pdpageouts++; 776 result = uvm_pager_put(swap_backed ? NULL : uobj, p, 777 &ppsp, &npages, PGO_ALLPAGES|PGO_PDFREECLUST, start, 0); 778 /* unlocked: pageqs, uobj */ 779 780 /* 781 * if we did i/o to swap, zero swslot to indicate that we are 782 * no longer building a swap-backed cluster. 783 */ 784 785 if (swap_backed) 786 swslot = 0; /* done with this cluster */ 787 788 /* 789 * if the pageout failed, reactivate the page and continue. 790 */ 791 792 if (result == EIO && curproc == uvm.pagedaemon_proc) { 793 uvm_lock_pageq(); 794 nextpg = TAILQ_NEXT(p, pageq); 795 uvm_pageactivate(p); 796 continue; 797 } 798 799 /* 800 * the pageout is in progress. bump counters and set up 801 * for the next loop. 802 */ 803 804 uvm_lock_pageq(); 805 uvmexp.paging += npages; 806 uvmexp.pdpending++; 807 if (p) { 808 if (p->pqflags & PQ_INACTIVE) 809 nextpg = TAILQ_NEXT(p, pageq); 810 else 811 nextpg = TAILQ_FIRST(pglst); 812 } else { 813 nextpg = NULL; 814 } 815 } 816 return (retval); 817 } 818 819 /* 820 * uvmpd_scan: scan the page queues and attempt to meet our targets. 821 * 822 * => called with pageq's locked 823 */ 824 825 void 826 uvmpd_scan() 827 { 828 int s, free, inactive_shortage, swap_shortage, pages_freed; 829 struct vm_page *p, *nextpg; 830 struct uvm_object *uobj; 831 boolean_t got_it; 832 UVMHIST_FUNC("uvmpd_scan"); UVMHIST_CALLED(pdhist); 833 834 uvmexp.pdrevs++; /* counter */ 835 uobj = NULL; 836 837 /* 838 * get current "free" page count 839 */ 840 s = uvm_lock_fpageq(); 841 free = uvmexp.free; 842 uvm_unlock_fpageq(s); 843 844 #ifndef __SWAP_BROKEN 845 /* 846 * swap out some processes if we are below our free target. 847 * we need to unlock the page queues for this. 848 */ 849 if (free < uvmexp.freetarg) { 850 uvmexp.pdswout++; 851 UVMHIST_LOG(pdhist," free %d < target %d: swapout", free, 852 uvmexp.freetarg, 0, 0); 853 uvm_unlock_pageq(); 854 uvm_swapout_threads(); 855 uvm_lock_pageq(); 856 857 } 858 #endif 859 860 /* 861 * now we want to work on meeting our targets. first we work on our 862 * free target by converting inactive pages into free pages. then 863 * we work on meeting our inactive target by converting active pages 864 * to inactive ones. 865 */ 866 867 UVMHIST_LOG(pdhist, " starting 'free' loop",0,0,0,0); 868 869 /* 870 * alternate starting queue between swap and object based on the 871 * low bit of uvmexp.pdrevs (which we bump by one each call). 872 */ 873 874 got_it = FALSE; 875 pages_freed = uvmexp.pdfreed; 876 if ((uvmexp.pdrevs & 1) != 0 && uvmexp.nswapdev != 0) 877 got_it = uvmpd_scan_inactive(&uvm.page_inactive_swp); 878 if (!got_it) 879 got_it = uvmpd_scan_inactive(&uvm.page_inactive_obj); 880 if (!got_it && (uvmexp.pdrevs & 1) == 0 && uvmexp.nswapdev != 0) 881 (void) uvmpd_scan_inactive(&uvm.page_inactive_swp); 882 pages_freed = uvmexp.pdfreed - pages_freed; 883 884 /* 885 * we have done the scan to get free pages. now we work on meeting 886 * our inactive target. 887 */ 888 889 inactive_shortage = uvmexp.inactarg - uvmexp.inactive; 890 891 /* 892 * detect if we're not going to be able to page anything out 893 * until we free some swap resources from active pages. 894 */ 895 896 swap_shortage = 0; 897 if (uvmexp.free < uvmexp.freetarg && 898 uvmexp.swpginuse == uvmexp.swpages && 899 uvmexp.swpgonly < uvmexp.swpages && 900 pages_freed == 0) { 901 swap_shortage = uvmexp.freetarg - uvmexp.free; 902 } 903 904 UVMHIST_LOG(pdhist, " loop 2: inactive_shortage=%d swap_shortage=%d", 905 inactive_shortage, swap_shortage,0,0); 906 for (p = TAILQ_FIRST(&uvm.page_active); 907 p != NULL && (inactive_shortage > 0 || swap_shortage > 0); 908 p = nextpg) { 909 nextpg = TAILQ_NEXT(p, pageq); 910 if (p->flags & PG_BUSY) 911 continue; /* quick check before trying to lock */ 912 913 /* 914 * lock the page's owner. 915 */ 916 /* is page anon owned or ownerless? */ 917 if ((p->pqflags & PQ_ANON) || p->uobject == NULL) { 918 KASSERT(p->uanon != NULL); 919 if (!simple_lock_try(&p->uanon->an_lock)) 920 continue; 921 922 /* take over the page? */ 923 if ((p->pqflags & PQ_ANON) == 0) { 924 KASSERT(p->loan_count > 0); 925 p->loan_count--; 926 p->pqflags |= PQ_ANON; 927 } 928 } else { 929 if (!simple_lock_try(&p->uobject->vmobjlock)) 930 continue; 931 } 932 933 /* 934 * skip this page if it's busy. 935 */ 936 937 if ((p->flags & PG_BUSY) != 0) { 938 if (p->pqflags & PQ_ANON) 939 simple_unlock(&p->uanon->an_lock); 940 else 941 simple_unlock(&p->uobject->vmobjlock); 942 continue; 943 } 944 945 /* 946 * if there's a shortage of swap, free any swap allocated 947 * to this page so that other pages can be paged out. 948 */ 949 950 if (swap_shortage > 0) { 951 if ((p->pqflags & PQ_ANON) && p->uanon->an_swslot) { 952 uvm_swap_free(p->uanon->an_swslot, 1); 953 p->uanon->an_swslot = 0; 954 p->flags &= ~PG_CLEAN; 955 swap_shortage--; 956 } 957 if (p->pqflags & PQ_AOBJ) { 958 int slot = uao_set_swslot(p->uobject, 959 p->offset >> PAGE_SHIFT, 0); 960 if (slot) { 961 uvm_swap_free(slot, 1); 962 p->flags &= ~PG_CLEAN; 963 swap_shortage--; 964 } 965 } 966 } 967 968 /* 969 * If the page has not been referenced since the 970 * last scan, deactivate the page if there is a 971 * shortage of inactive pages. 972 */ 973 974 if (inactive_shortage > 0 && 975 pmap_clear_reference(p) == FALSE) { 976 /* no need to check wire_count as pg is "active" */ 977 uvm_pagedeactivate(p); 978 uvmexp.pddeact++; 979 inactive_shortage--; 980 } 981 if (p->pqflags & PQ_ANON) 982 simple_unlock(&p->uanon->an_lock); 983 else 984 simple_unlock(&p->uobject->vmobjlock); 985 } 986 } 987