1 /* 2 * (MPSAFE) 3 * 4 * Copyright (c) 2010 The DragonFly Project. All rights reserved. 5 * 6 * This code is derived from software contributed to The DragonFly Project 7 * by Matthew Dillon <dillon@backplane.com> 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in 17 * the documentation and/or other materials provided with the 18 * distribution. 19 * 3. Neither the name of The DragonFly Project nor the names of its 20 * contributors may be used to endorse or promote products derived 21 * from this software without specific, prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 24 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 25 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 26 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 27 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 28 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING, 29 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 30 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 31 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 32 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 33 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 */ 36 37 /* 38 * Implement the swapcache daemon. When enabled swap is assumed to be 39 * configured on a fast storage device such as a SSD. Swap is assigned 40 * to clean vnode-backed pages in the inactive queue, clustered by object 41 * if possible, and written out. The swap assignment sticks around even 42 * after the underlying pages have been recycled. 43 * 44 * The daemon manages write bandwidth based on sysctl settings to control 45 * wear on the SSD. 46 * 47 * The vnode strategy code will check for the swap assignments and divert 48 * reads to the swap device when the data is present in the swapcache. 49 * 50 * This operates on both regular files and the block device vnodes used by 51 * filesystems to manage meta-data. 52 */ 53 54 #include "opt_vm.h" 55 #include <sys/param.h> 56 #include <sys/systm.h> 57 #include <sys/kernel.h> 58 #include <sys/proc.h> 59 #include <sys/kthread.h> 60 #include <sys/resourcevar.h> 61 #include <sys/signalvar.h> 62 #include <sys/vnode.h> 63 #include <sys/vmmeter.h> 64 #include <sys/sysctl.h> 65 #include <sys/eventhandler.h> 66 67 #include <vm/vm.h> 68 #include <vm/vm_param.h> 69 #include <sys/lock.h> 70 #include <vm/vm_object.h> 71 #include <vm/vm_page.h> 72 #include <vm/vm_map.h> 73 #include <vm/vm_pageout.h> 74 #include <vm/vm_pager.h> 75 #include <vm/swap_pager.h> 76 #include <vm/vm_extern.h> 77 78 #include <sys/thread2.h> 79 #include <sys/spinlock2.h> 80 #include <vm/vm_page2.h> 81 82 /* the kernel process "vm_pageout"*/ 83 static int vm_swapcached_flush (vm_page_t m, int isblkdev); 84 static int vm_swapcache_test(vm_page_t m); 85 static int vm_swapcache_writing_heuristic(void); 86 static int vm_swapcache_writing(vm_page_t marker, int count, int scount); 87 static void vm_swapcache_cleaning(vm_object_t marker, int *swindexp); 88 static void vm_swapcache_movemarker(vm_object_t marker, int swindex, 89 vm_object_t object); 90 struct thread *swapcached_thread; 91 92 SYSCTL_NODE(_vm, OID_AUTO, swapcache, CTLFLAG_RW, NULL, NULL); 93 94 int vm_swapcache_read_enable; 95 int vm_swapcache_inactive_heuristic; 96 static int vm_swapcache_sleep; 97 static int vm_swapcache_maxscan = PQ_L2_SIZE * 8; 98 static int vm_swapcache_maxlaunder = PQ_L2_SIZE * 4; 99 static int vm_swapcache_data_enable = 0; 100 static int vm_swapcache_meta_enable = 0; 101 static int vm_swapcache_maxswappct = 75; 102 static int vm_swapcache_hysteresis; 103 static int vm_swapcache_min_hysteresis; 104 int vm_swapcache_use_chflags = 1; /* require chflags cache */ 105 static int64_t vm_swapcache_minburst = 10000000LL; /* 10MB */ 106 static int64_t vm_swapcache_curburst = 4000000000LL; /* 4G after boot */ 107 static int64_t vm_swapcache_maxburst = 2000000000LL; /* 2G nominal max */ 108 static int64_t vm_swapcache_accrate = 100000LL; /* 100K/s */ 109 static int64_t vm_swapcache_write_count; 110 static int64_t vm_swapcache_maxfilesize; 111 static int64_t vm_swapcache_cleanperobj = 16*1024*1024; 112 113 SYSCTL_INT(_vm_swapcache, OID_AUTO, maxlaunder, 114 CTLFLAG_RW, &vm_swapcache_maxlaunder, 0, ""); 115 SYSCTL_INT(_vm_swapcache, OID_AUTO, maxscan, 116 CTLFLAG_RW, &vm_swapcache_maxscan, 0, ""); 117 118 SYSCTL_INT(_vm_swapcache, OID_AUTO, data_enable, 119 CTLFLAG_RW, &vm_swapcache_data_enable, 0, ""); 120 SYSCTL_INT(_vm_swapcache, OID_AUTO, meta_enable, 121 CTLFLAG_RW, &vm_swapcache_meta_enable, 0, ""); 122 SYSCTL_INT(_vm_swapcache, OID_AUTO, read_enable, 123 CTLFLAG_RW, &vm_swapcache_read_enable, 0, ""); 124 SYSCTL_INT(_vm_swapcache, OID_AUTO, maxswappct, 125 CTLFLAG_RW, &vm_swapcache_maxswappct, 0, ""); 126 SYSCTL_INT(_vm_swapcache, OID_AUTO, hysteresis, 127 CTLFLAG_RD, &vm_swapcache_hysteresis, 0, ""); 128 SYSCTL_INT(_vm_swapcache, OID_AUTO, min_hysteresis, 129 CTLFLAG_RW, &vm_swapcache_min_hysteresis, 0, ""); 130 SYSCTL_INT(_vm_swapcache, OID_AUTO, use_chflags, 131 CTLFLAG_RW, &vm_swapcache_use_chflags, 0, ""); 132 133 SYSCTL_QUAD(_vm_swapcache, OID_AUTO, minburst, 134 CTLFLAG_RW, &vm_swapcache_minburst, 0, ""); 135 SYSCTL_QUAD(_vm_swapcache, OID_AUTO, curburst, 136 CTLFLAG_RW, &vm_swapcache_curburst, 0, ""); 137 SYSCTL_QUAD(_vm_swapcache, OID_AUTO, maxburst, 138 CTLFLAG_RW, &vm_swapcache_maxburst, 0, ""); 139 SYSCTL_QUAD(_vm_swapcache, OID_AUTO, maxfilesize, 140 CTLFLAG_RW, &vm_swapcache_maxfilesize, 0, ""); 141 SYSCTL_QUAD(_vm_swapcache, OID_AUTO, accrate, 142 CTLFLAG_RW, &vm_swapcache_accrate, 0, ""); 143 SYSCTL_QUAD(_vm_swapcache, OID_AUTO, write_count, 144 CTLFLAG_RW, &vm_swapcache_write_count, 0, ""); 145 SYSCTL_QUAD(_vm_swapcache, OID_AUTO, cleanperobj, 146 CTLFLAG_RW, &vm_swapcache_cleanperobj, 0, ""); 147 148 #define SWAPMAX(adj) \ 149 ((int64_t)vm_swap_max * (vm_swapcache_maxswappct + (adj)) / 100) 150 151 /* 152 * When shutting down the machine we want to stop swapcache operation 153 * immediately so swap is not accessed after devices have been shuttered. 154 */ 155 static void 156 shutdown_swapcache(void *arg __unused) 157 { 158 vm_swapcache_read_enable = 0; 159 vm_swapcache_data_enable = 0; 160 vm_swapcache_meta_enable = 0; 161 wakeup(&vm_swapcache_sleep); /* shortcut 5-second wait */ 162 } 163 164 /* 165 * vm_swapcached is the high level pageout daemon. 166 * 167 * No requirements. 168 */ 169 static void 170 vm_swapcached_thread(void) 171 { 172 enum { SWAPC_WRITING, SWAPC_CLEANING } state = SWAPC_WRITING; 173 enum { SWAPB_BURSTING, SWAPB_RECOVERING } burst = SWAPB_BURSTING; 174 static struct vm_page page_marker[PQ_L2_SIZE]; 175 static struct vm_object swmarker; 176 static int swindex; 177 int q; 178 179 /* 180 * Thread setup 181 */ 182 curthread->td_flags |= TDF_SYSTHREAD; 183 EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_kproc, 184 swapcached_thread, SHUTDOWN_PRI_FIRST); 185 EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_swapcache, 186 NULL, SHUTDOWN_PRI_SECOND); 187 188 /* 189 * Initialize our marker for the inactive scan (SWAPC_WRITING) 190 */ 191 bzero(&page_marker, sizeof(page_marker)); 192 for (q = 0; q < PQ_L2_SIZE; ++q) { 193 page_marker[q].flags = PG_BUSY | PG_FICTITIOUS | PG_MARKER; 194 page_marker[q].queue = PQ_INACTIVE + q; 195 page_marker[q].pc = q; 196 page_marker[q].wire_count = 1; 197 vm_page_queues_spin_lock(PQ_INACTIVE + q); 198 TAILQ_INSERT_HEAD( 199 &vm_page_queues[PQ_INACTIVE + q].pl, 200 &page_marker[q], pageq); 201 vm_page_queues_spin_unlock(PQ_INACTIVE + q); 202 } 203 204 vm_swapcache_min_hysteresis = 1024; 205 vm_swapcache_hysteresis = vm_swapcache_min_hysteresis; 206 vm_swapcache_inactive_heuristic = -vm_swapcache_hysteresis; 207 208 /* 209 * Initialize our marker for the vm_object scan (SWAPC_CLEANING) 210 */ 211 bzero(&swmarker, sizeof(swmarker)); 212 swmarker.type = OBJT_MARKER; 213 swindex = 0; 214 lwkt_gettoken(&vmobj_tokens[swindex]); 215 TAILQ_INSERT_HEAD(&vm_object_lists[swindex], 216 &swmarker, object_list); 217 lwkt_reltoken(&vmobj_tokens[swindex]); 218 219 for (;;) { 220 int reached_end; 221 int scount; 222 int count; 223 224 /* 225 * Handle shutdown 226 */ 227 kproc_suspend_loop(); 228 229 /* 230 * Check every 5 seconds when not enabled or if no swap 231 * is present. 232 */ 233 if ((vm_swapcache_data_enable == 0 && 234 vm_swapcache_meta_enable == 0 && 235 vm_swap_cache_use <= SWAPMAX(0)) || 236 vm_swap_max == 0) { 237 tsleep(&vm_swapcache_sleep, 0, "csleep", hz * 5); 238 continue; 239 } 240 241 /* 242 * Polling rate when enabled is approximately 10 hz. 243 */ 244 tsleep(&vm_swapcache_sleep, 0, "csleep", hz / 10); 245 246 /* 247 * State hysteresis. Generate write activity up to 75% of 248 * swap, then clean out swap assignments down to 70%, then 249 * repeat. 250 */ 251 if (state == SWAPC_WRITING) { 252 if (vm_swap_cache_use > SWAPMAX(0)) 253 state = SWAPC_CLEANING; 254 } else { 255 if (vm_swap_cache_use < SWAPMAX(-10)) 256 state = SWAPC_WRITING; 257 } 258 259 /* 260 * We are allowed to continue accumulating burst value 261 * in either state. Allow the user to set curburst > maxburst 262 * for the initial load-in. 263 */ 264 if (vm_swapcache_curburst < vm_swapcache_maxburst) { 265 vm_swapcache_curburst += vm_swapcache_accrate / 10; 266 if (vm_swapcache_curburst > vm_swapcache_maxburst) 267 vm_swapcache_curburst = vm_swapcache_maxburst; 268 } 269 270 /* 271 * We don't want to nickle-and-dime the scan as that will 272 * create unnecessary fragmentation. The minimum burst 273 * is one-seconds worth of accumulation. 274 */ 275 if (state != SWAPC_WRITING) { 276 vm_swapcache_cleaning(&swmarker, &swindex); 277 continue; 278 } 279 if (vm_swapcache_curburst < vm_swapcache_accrate) 280 continue; 281 282 reached_end = 0; 283 count = vm_swapcache_maxlaunder / PQ_L2_SIZE + 2; 284 scount = vm_swapcache_maxscan / PQ_L2_SIZE + 2; 285 286 if (burst == SWAPB_BURSTING) { 287 if (vm_swapcache_writing_heuristic()) { 288 for (q = 0; q < PQ_L2_SIZE; ++q) { 289 reached_end += 290 vm_swapcache_writing( 291 &page_marker[q], 292 count, 293 scount); 294 } 295 } 296 if (vm_swapcache_curburst <= 0) 297 burst = SWAPB_RECOVERING; 298 } else if (vm_swapcache_curburst > vm_swapcache_minburst) { 299 if (vm_swapcache_writing_heuristic()) { 300 for (q = 0; q < PQ_L2_SIZE; ++q) { 301 reached_end += 302 vm_swapcache_writing( 303 &page_marker[q], 304 count, 305 scount); 306 } 307 } 308 burst = SWAPB_BURSTING; 309 } 310 if (reached_end == PQ_L2_SIZE) { 311 vm_swapcache_inactive_heuristic = 312 -vm_swapcache_hysteresis; 313 } 314 } 315 316 /* 317 * Cleanup (NOT REACHED) 318 */ 319 for (q = 0; q < PQ_L2_SIZE; ++q) { 320 vm_page_queues_spin_lock(PQ_INACTIVE + q); 321 TAILQ_REMOVE( 322 &vm_page_queues[PQ_INACTIVE + q].pl, 323 &page_marker[q], pageq); 324 vm_page_queues_spin_unlock(PQ_INACTIVE + q); 325 } 326 327 lwkt_gettoken(&vmobj_tokens[swindex]); 328 TAILQ_REMOVE(&vm_object_lists[swindex], &swmarker, object_list); 329 lwkt_reltoken(&vmobj_tokens[swindex]); 330 } 331 332 static struct kproc_desc swpc_kp = { 333 "swapcached", 334 vm_swapcached_thread, 335 &swapcached_thread 336 }; 337 SYSINIT(swapcached, SI_SUB_KTHREAD_PAGE, SI_ORDER_SECOND, kproc_start, &swpc_kp); 338 339 /* 340 * Deal with an overflow of the heuristic counter or if the user 341 * manually changes the hysteresis. 342 * 343 * Try to avoid small incremental pageouts by waiting for enough 344 * pages to buildup in the inactive queue to hopefully get a good 345 * burst in. This heuristic is bumped by the VM system and reset 346 * when our scan hits the end of the queue. 347 * 348 * Return TRUE if we need to take a writing pass. 349 */ 350 static int 351 vm_swapcache_writing_heuristic(void) 352 { 353 int hyst; 354 355 hyst = vmstats.v_inactive_count / 4; 356 if (hyst < vm_swapcache_min_hysteresis) 357 hyst = vm_swapcache_min_hysteresis; 358 cpu_ccfence(); 359 vm_swapcache_hysteresis = hyst; 360 361 if (vm_swapcache_inactive_heuristic < -hyst) 362 vm_swapcache_inactive_heuristic = -hyst; 363 364 return (vm_swapcache_inactive_heuristic >= 0); 365 } 366 367 /* 368 * Take a writing pass on one of the inactive queues, return non-zero if 369 * we hit the end of the queue. 370 */ 371 static int 372 vm_swapcache_writing(vm_page_t marker, int count, int scount) 373 { 374 vm_object_t object; 375 struct vnode *vp; 376 vm_page_t m; 377 int isblkdev; 378 379 /* 380 * Scan the inactive queue from our marker to locate 381 * suitable pages to push to the swap cache. 382 * 383 * We are looking for clean vnode-backed pages. 384 */ 385 vm_page_queues_spin_lock(marker->queue); 386 while ((m = TAILQ_NEXT(marker, pageq)) != NULL && 387 count > 0 && scount-- > 0) { 388 KKASSERT(m->queue == marker->queue); 389 390 /* 391 * Stop using swap if paniced, dumping, or dumped. 392 * Don't try to write if our curburst has been exhausted. 393 */ 394 if (panicstr || dumping) 395 break; 396 if (vm_swapcache_curburst < 0) 397 break; 398 399 /* 400 * Move marker 401 */ 402 TAILQ_REMOVE( 403 &vm_page_queues[marker->queue].pl, marker, pageq); 404 TAILQ_INSERT_AFTER( 405 &vm_page_queues[marker->queue].pl, m, marker, pageq); 406 407 /* 408 * Ignore markers and ignore pages that already have a swap 409 * assignment. 410 */ 411 if (m->flags & (PG_MARKER | PG_SWAPPED)) 412 continue; 413 if (vm_page_busy_try(m, TRUE)) 414 continue; 415 vm_page_queues_spin_unlock(marker->queue); 416 417 if ((object = m->object) == NULL) { 418 vm_page_wakeup(m); 419 vm_page_queues_spin_lock(marker->queue); 420 continue; 421 } 422 vm_object_hold(object); 423 if (m->object != object) { 424 vm_object_drop(object); 425 vm_page_wakeup(m); 426 vm_page_queues_spin_lock(marker->queue); 427 continue; 428 } 429 if (vm_swapcache_test(m)) { 430 vm_object_drop(object); 431 vm_page_wakeup(m); 432 vm_page_queues_spin_lock(marker->queue); 433 continue; 434 } 435 436 vp = object->handle; 437 if (vp == NULL) { 438 vm_object_drop(object); 439 vm_page_wakeup(m); 440 vm_page_queues_spin_lock(marker->queue); 441 continue; 442 } 443 444 switch(vp->v_type) { 445 case VREG: 446 /* 447 * PG_NOTMETA generically means 'don't swapcache this', 448 * and HAMMER will set this for regular data buffers 449 * (and leave it unset for meta-data buffers) as 450 * appropriate when double buffering is enabled. 451 */ 452 if (m->flags & PG_NOTMETA) { 453 vm_object_drop(object); 454 vm_page_wakeup(m); 455 vm_page_queues_spin_lock(marker->queue); 456 continue; 457 } 458 459 /* 460 * If data_enable is 0 do not try to swapcache data. 461 * If use_chflags is set then only swapcache data for 462 * VSWAPCACHE marked vnodes, otherwise any vnode. 463 */ 464 if (vm_swapcache_data_enable == 0 || 465 ((vp->v_flag & VSWAPCACHE) == 0 && 466 vm_swapcache_use_chflags)) { 467 vm_object_drop(object); 468 vm_page_wakeup(m); 469 vm_page_queues_spin_lock(marker->queue); 470 continue; 471 } 472 if (vm_swapcache_maxfilesize && 473 object->size > 474 (vm_swapcache_maxfilesize >> PAGE_SHIFT)) { 475 vm_object_drop(object); 476 vm_page_wakeup(m); 477 vm_page_queues_spin_lock(marker->queue); 478 continue; 479 } 480 isblkdev = 0; 481 break; 482 case VCHR: 483 /* 484 * PG_NOTMETA generically means 'don't swapcache this', 485 * and HAMMER will set this for regular data buffers 486 * (and leave it unset for meta-data buffers) as 487 * appropriate when double buffering is enabled. 488 */ 489 if (m->flags & PG_NOTMETA) { 490 vm_object_drop(object); 491 vm_page_wakeup(m); 492 vm_page_queues_spin_lock(marker->queue); 493 continue; 494 } 495 if (vm_swapcache_meta_enable == 0) { 496 vm_object_drop(object); 497 vm_page_wakeup(m); 498 vm_page_queues_spin_lock(marker->queue); 499 continue; 500 } 501 isblkdev = 1; 502 break; 503 default: 504 vm_object_drop(object); 505 vm_page_wakeup(m); 506 vm_page_queues_spin_lock(marker->queue); 507 continue; 508 } 509 510 511 /* 512 * Assign swap and initiate I/O. 513 * 514 * (adjust for the --count which also occurs in the loop) 515 */ 516 count -= vm_swapcached_flush(m, isblkdev); 517 518 /* 519 * Setup for next loop using marker. 520 */ 521 vm_object_drop(object); 522 vm_page_queues_spin_lock(marker->queue); 523 } 524 525 /* 526 * The marker could wind up at the end, which is ok. If we hit the 527 * end of the list adjust the heuristic. 528 * 529 * Earlier inactive pages that were dirty and become clean 530 * are typically moved to the end of PQ_INACTIVE by virtue 531 * of vfs_vmio_release() when they become unwired from the 532 * buffer cache. 533 */ 534 vm_page_queues_spin_unlock(marker->queue); 535 536 /* 537 * m invalid but can be used to test for NULL 538 */ 539 return (m == NULL); 540 } 541 542 /* 543 * Flush the specified page using the swap_pager. The page 544 * must be busied by the caller and its disposition will become 545 * the responsibility of this function. 546 * 547 * Try to collect surrounding pages, including pages which may 548 * have already been assigned swap. Try to cluster within a 549 * contiguous aligned SMAP_META_PAGES (typ 16 x PAGE_SIZE) block 550 * to match what swap_pager_putpages() can do. 551 * 552 * We also want to try to match against the buffer cache blocksize 553 * but we don't really know what it is here. Since the buffer cache 554 * wires and unwires pages in groups the fact that we skip wired pages 555 * should be sufficient. 556 * 557 * Returns a count of pages we might have flushed (minimum 1) 558 */ 559 static 560 int 561 vm_swapcached_flush(vm_page_t m, int isblkdev) 562 { 563 vm_object_t object; 564 vm_page_t marray[SWAP_META_PAGES]; 565 vm_pindex_t basei; 566 int rtvals[SWAP_META_PAGES]; 567 int x; 568 int i; 569 int j; 570 int count; 571 int error; 572 573 vm_page_io_start(m); 574 vm_page_protect(m, VM_PROT_READ); 575 object = m->object; 576 vm_object_hold(object); 577 578 /* 579 * Try to cluster around (m), keeping in mind that the swap pager 580 * can only do SMAP_META_PAGES worth of continguous write. 581 */ 582 x = (int)m->pindex & SWAP_META_MASK; 583 marray[x] = m; 584 basei = m->pindex; 585 vm_page_wakeup(m); 586 587 for (i = x - 1; i >= 0; --i) { 588 m = vm_page_lookup_busy_try(object, basei - x + i, 589 TRUE, &error); 590 if (error || m == NULL) 591 break; 592 if (vm_swapcache_test(m)) { 593 vm_page_wakeup(m); 594 break; 595 } 596 if (isblkdev && (m->flags & PG_NOTMETA)) { 597 vm_page_wakeup(m); 598 break; 599 } 600 vm_page_io_start(m); 601 vm_page_protect(m, VM_PROT_READ); 602 if (m->queue - m->pc == PQ_CACHE) { 603 vm_page_unqueue_nowakeup(m); 604 vm_page_deactivate(m); 605 } 606 marray[i] = m; 607 vm_page_wakeup(m); 608 } 609 ++i; 610 611 for (j = x + 1; j < SWAP_META_PAGES; ++j) { 612 m = vm_page_lookup_busy_try(object, basei - x + j, 613 TRUE, &error); 614 if (error || m == NULL) 615 break; 616 if (vm_swapcache_test(m)) { 617 vm_page_wakeup(m); 618 break; 619 } 620 if (isblkdev && (m->flags & PG_NOTMETA)) { 621 vm_page_wakeup(m); 622 break; 623 } 624 vm_page_io_start(m); 625 vm_page_protect(m, VM_PROT_READ); 626 if (m->queue - m->pc == PQ_CACHE) { 627 vm_page_unqueue_nowakeup(m); 628 vm_page_deactivate(m); 629 } 630 marray[j] = m; 631 vm_page_wakeup(m); 632 } 633 634 count = j - i; 635 vm_object_pip_add(object, count); 636 swap_pager_putpages(object, marray + i, count, FALSE, rtvals + i); 637 vm_swapcache_write_count += count * PAGE_SIZE; 638 vm_swapcache_curburst -= count * PAGE_SIZE; 639 640 while (i < j) { 641 if (rtvals[i] != VM_PAGER_PEND) { 642 vm_page_busy_wait(marray[i], FALSE, "swppgfd"); 643 vm_page_io_finish(marray[i]); 644 vm_page_wakeup(marray[i]); 645 vm_object_pip_wakeup(object); 646 } 647 ++i; 648 } 649 vm_object_drop(object); 650 return(count); 651 } 652 653 /* 654 * Test whether a VM page is suitable for writing to the swapcache. 655 * Does not test m->queue, PG_MARKER, or PG_SWAPPED. 656 * 657 * Returns 0 on success, 1 on failure 658 */ 659 static int 660 vm_swapcache_test(vm_page_t m) 661 { 662 vm_object_t object; 663 664 if (m->flags & PG_UNMANAGED) 665 return(1); 666 if (m->hold_count || m->wire_count) 667 return(1); 668 if (m->valid != VM_PAGE_BITS_ALL) 669 return(1); 670 if (m->dirty & m->valid) 671 return(1); 672 if ((object = m->object) == NULL) 673 return(1); 674 if (object->type != OBJT_VNODE || 675 (object->flags & OBJ_DEAD)) { 676 return(1); 677 } 678 vm_page_test_dirty(m); 679 if (m->dirty & m->valid) 680 return(1); 681 return(0); 682 } 683 684 /* 685 * Cleaning pass. 686 * 687 * We clean whole objects up to 16MB 688 */ 689 static 690 void 691 vm_swapcache_cleaning(vm_object_t marker, int *swindexp) 692 { 693 vm_object_t object; 694 struct vnode *vp; 695 int count; 696 int scount; 697 int n; 698 699 count = vm_swapcache_maxlaunder; 700 scount = vm_swapcache_maxscan; 701 702 /* 703 * Look for vnode objects 704 */ 705 lwkt_gettoken(&vmobj_tokens[*swindexp]); 706 707 outerloop: 708 while ((object = TAILQ_NEXT(marker, object_list)) != NULL) { 709 /* 710 * We have to skip markers. We cannot hold/drop marker 711 * objects! 712 */ 713 if (object->type == OBJT_MARKER) { 714 vm_swapcache_movemarker(marker, *swindexp, object); 715 continue; 716 } 717 718 /* 719 * Safety, or in case there are millions of VM objects 720 * without swapcache backing. 721 */ 722 if (--scount <= 0) 723 goto breakout; 724 725 /* 726 * We must hold the object before potentially yielding. 727 */ 728 vm_object_hold(object); 729 lwkt_yield(); 730 731 /* 732 * Only operate on live VNODE objects that are either 733 * VREG or VCHR (VCHR for meta-data). 734 */ 735 if ((object->type != OBJT_VNODE) || 736 ((object->flags & OBJ_DEAD) || 737 object->swblock_count == 0) || 738 ((vp = object->handle) == NULL) || 739 (vp->v_type != VREG && vp->v_type != VCHR)) { 740 vm_object_drop(object); 741 /* object may be invalid now */ 742 vm_swapcache_movemarker(marker, *swindexp, object); 743 continue; 744 } 745 746 /* 747 * Reset the object pindex stored in the marker if the 748 * working object has changed. 749 */ 750 if (marker->backing_object != object) { 751 marker->size = 0; 752 marker->backing_object_offset = 0; 753 marker->backing_object = object; 754 } 755 756 /* 757 * Look for swblocks starting at our iterator. 758 * 759 * The swap_pager_condfree() function attempts to free 760 * swap space starting at the specified index. The index 761 * will be updated on return. The function will return 762 * a scan factor (NOT the number of blocks freed). 763 * 764 * If it must cut its scan of the object short due to an 765 * excessive number of swblocks, or is able to free the 766 * requested number of blocks, it will return n >= count 767 * and we break and pick it back up on a future attempt. 768 * 769 * Scan the object linearly and try to batch large sets of 770 * blocks that are likely to clean out entire swap radix 771 * tree leafs. 772 */ 773 lwkt_token_swap(); 774 lwkt_reltoken(&vmobj_tokens[*swindexp]); 775 776 n = swap_pager_condfree(object, &marker->size, 777 (count + SWAP_META_MASK) & ~SWAP_META_MASK); 778 779 vm_object_drop(object); /* object may be invalid now */ 780 lwkt_gettoken(&vmobj_tokens[*swindexp]); 781 782 /* 783 * If we have exhausted the object or deleted our per-pass 784 * page limit then move us to the next object. Note that 785 * the current object may no longer be on the vm_object_list. 786 */ 787 if (n <= 0 || 788 marker->backing_object_offset > vm_swapcache_cleanperobj) { 789 vm_swapcache_movemarker(marker, *swindexp, object); 790 } 791 792 /* 793 * If we have exhausted our max-launder stop for now. 794 */ 795 count -= n; 796 marker->backing_object_offset += n * PAGE_SIZE; 797 if (count < 0) 798 goto breakout; 799 } 800 801 /* 802 * Iterate vm_object_lists[] hash table 803 */ 804 TAILQ_REMOVE(&vm_object_lists[*swindexp], marker, object_list); 805 lwkt_reltoken(&vmobj_tokens[*swindexp]); 806 if (++*swindexp >= VMOBJ_HSIZE) 807 *swindexp = 0; 808 lwkt_gettoken(&vmobj_tokens[*swindexp]); 809 TAILQ_INSERT_HEAD(&vm_object_lists[*swindexp], marker, object_list); 810 811 if (*swindexp != 0) 812 goto outerloop; 813 814 breakout: 815 lwkt_reltoken(&vmobj_tokens[*swindexp]); 816 } 817 818 /* 819 * Move the marker past the current object. Object can be stale, but we 820 * still need it to determine if the marker has to be moved. If the object 821 * is still the 'current object' (object after the marker), we hop-scotch 822 * the marker past it. 823 */ 824 static void 825 vm_swapcache_movemarker(vm_object_t marker, int swindex, vm_object_t object) 826 { 827 if (TAILQ_NEXT(marker, object_list) == object) { 828 TAILQ_REMOVE(&vm_object_lists[swindex], marker, object_list); 829 TAILQ_INSERT_AFTER(&vm_object_lists[swindex], object, 830 marker, object_list); 831 } 832 } 833