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, 88 struct vm_object_hash **swindexp); 89 static void vm_swapcache_movemarker(vm_object_t marker, 90 struct vm_object_hash *swindex, vm_object_t object); 91 struct thread *swapcached_thread; 92 93 SYSCTL_NODE(_vm, OID_AUTO, swapcache, CTLFLAG_RW, NULL, NULL); 94 95 int vm_swapcache_read_enable; 96 int vm_swapcache_inactive_heuristic; 97 static int vm_swapcache_sleep; 98 static int vm_swapcache_maxscan = PQ_L2_SIZE * 8; 99 static int vm_swapcache_maxlaunder = PQ_L2_SIZE * 4; 100 static int vm_swapcache_data_enable = 0; 101 static int vm_swapcache_meta_enable = 0; 102 static int vm_swapcache_maxswappct = 75; 103 static int vm_swapcache_hysteresis; 104 static int vm_swapcache_min_hysteresis; 105 int vm_swapcache_use_chflags = 0; /* require chflags cache */ 106 static int64_t vm_swapcache_minburst = 10000000LL; /* 10MB */ 107 static int64_t vm_swapcache_curburst = 4000000000LL; /* 4G after boot */ 108 static int64_t vm_swapcache_maxburst = 2000000000LL; /* 2G nominal max */ 109 static int64_t vm_swapcache_accrate = 100000LL; /* 100K/s */ 110 static int64_t vm_swapcache_write_count; 111 static int64_t vm_swapcache_maxfilesize; 112 static int64_t vm_swapcache_cleanperobj = 16*1024*1024; 113 114 SYSCTL_INT(_vm_swapcache, OID_AUTO, maxlaunder, 115 CTLFLAG_RW, &vm_swapcache_maxlaunder, 0, ""); 116 SYSCTL_INT(_vm_swapcache, OID_AUTO, maxscan, 117 CTLFLAG_RW, &vm_swapcache_maxscan, 0, ""); 118 119 SYSCTL_INT(_vm_swapcache, OID_AUTO, data_enable, 120 CTLFLAG_RW, &vm_swapcache_data_enable, 0, ""); 121 SYSCTL_INT(_vm_swapcache, OID_AUTO, meta_enable, 122 CTLFLAG_RW, &vm_swapcache_meta_enable, 0, ""); 123 SYSCTL_INT(_vm_swapcache, OID_AUTO, read_enable, 124 CTLFLAG_RW, &vm_swapcache_read_enable, 0, ""); 125 SYSCTL_INT(_vm_swapcache, OID_AUTO, maxswappct, 126 CTLFLAG_RW, &vm_swapcache_maxswappct, 0, ""); 127 SYSCTL_INT(_vm_swapcache, OID_AUTO, hysteresis, 128 CTLFLAG_RD, &vm_swapcache_hysteresis, 0, ""); 129 SYSCTL_INT(_vm_swapcache, OID_AUTO, min_hysteresis, 130 CTLFLAG_RW, &vm_swapcache_min_hysteresis, 0, ""); 131 SYSCTL_INT(_vm_swapcache, OID_AUTO, use_chflags, 132 CTLFLAG_RW, &vm_swapcache_use_chflags, 0, ""); 133 134 SYSCTL_QUAD(_vm_swapcache, OID_AUTO, minburst, 135 CTLFLAG_RW, &vm_swapcache_minburst, 0, ""); 136 SYSCTL_QUAD(_vm_swapcache, OID_AUTO, curburst, 137 CTLFLAG_RW, &vm_swapcache_curburst, 0, ""); 138 SYSCTL_QUAD(_vm_swapcache, OID_AUTO, maxburst, 139 CTLFLAG_RW, &vm_swapcache_maxburst, 0, ""); 140 SYSCTL_QUAD(_vm_swapcache, OID_AUTO, maxfilesize, 141 CTLFLAG_RW, &vm_swapcache_maxfilesize, 0, ""); 142 SYSCTL_QUAD(_vm_swapcache, OID_AUTO, accrate, 143 CTLFLAG_RW, &vm_swapcache_accrate, 0, ""); 144 SYSCTL_QUAD(_vm_swapcache, OID_AUTO, write_count, 145 CTLFLAG_RW, &vm_swapcache_write_count, 0, ""); 146 SYSCTL_QUAD(_vm_swapcache, OID_AUTO, cleanperobj, 147 CTLFLAG_RW, &vm_swapcache_cleanperobj, 0, ""); 148 149 #define SWAPMAX(adj) \ 150 ((int64_t)vm_swap_max * (vm_swapcache_maxswappct + (adj)) / 100) 151 152 /* 153 * When shutting down the machine we want to stop swapcache operation 154 * immediately so swap is not accessed after devices have been shuttered. 155 */ 156 static void 157 shutdown_swapcache(void *arg __unused) 158 { 159 vm_swapcache_read_enable = 0; 160 vm_swapcache_data_enable = 0; 161 vm_swapcache_meta_enable = 0; 162 wakeup(&vm_swapcache_sleep); /* shortcut 5-second wait */ 163 } 164 165 /* 166 * vm_swapcached is the high level pageout daemon. 167 * 168 * No requirements. 169 */ 170 static void 171 vm_swapcached_thread(void) 172 { 173 enum { SWAPC_WRITING, SWAPC_CLEANING } state = SWAPC_WRITING; 174 enum { SWAPB_BURSTING, SWAPB_RECOVERING } burst = SWAPB_BURSTING; 175 static struct vm_page page_marker[PQ_L2_SIZE]; 176 static struct vm_object swmarker; 177 static struct vm_object_hash *swindex; 178 int q; 179 180 /* 181 * Thread setup 182 */ 183 curthread->td_flags |= TDF_SYSTHREAD; 184 EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_kproc, 185 swapcached_thread, SHUTDOWN_PRI_FIRST); 186 EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_swapcache, 187 NULL, SHUTDOWN_PRI_SECOND); 188 189 /* 190 * Initialize our marker for the inactive scan (SWAPC_WRITING) 191 */ 192 bzero(&page_marker, sizeof(page_marker)); 193 for (q = 0; q < PQ_L2_SIZE; ++q) { 194 page_marker[q].flags = PG_FICTITIOUS | PG_MARKER; 195 page_marker[q].busy_count = PBUSY_LOCKED; 196 page_marker[q].queue = PQ_INACTIVE + q; 197 page_marker[q].pc = q; 198 page_marker[q].wire_count = 1; 199 vm_page_queues_spin_lock(PQ_INACTIVE + q); 200 TAILQ_INSERT_HEAD( 201 &vm_page_queues[PQ_INACTIVE + q].pl, 202 &page_marker[q], pageq); 203 vm_page_queues_spin_unlock(PQ_INACTIVE + q); 204 } 205 206 vm_swapcache_min_hysteresis = 1024; 207 vm_swapcache_hysteresis = vm_swapcache_min_hysteresis; 208 vm_swapcache_inactive_heuristic = -vm_swapcache_hysteresis; 209 210 /* 211 * Initialize our marker for the vm_object scan (SWAPC_CLEANING) 212 */ 213 bzero(&swmarker, sizeof(swmarker)); 214 swmarker.type = OBJT_MARKER; 215 swindex = &vm_object_hash[0]; 216 lwkt_gettoken(&swindex->token); 217 TAILQ_INSERT_HEAD(&swindex->list, &swmarker, object_list); 218 lwkt_reltoken(&swindex->token); 219 220 for (;;) { 221 int reached_end; 222 int scount; 223 int count; 224 225 /* 226 * Handle shutdown 227 */ 228 kproc_suspend_loop(); 229 230 /* 231 * Check every 5 seconds when not enabled or if no swap 232 * is present. 233 */ 234 if ((vm_swapcache_data_enable == 0 && 235 vm_swapcache_meta_enable == 0 && 236 vm_swap_cache_use <= SWAPMAX(0)) || 237 vm_swap_max == 0) { 238 tsleep(&vm_swapcache_sleep, 0, "csleep", hz * 5); 239 continue; 240 } 241 242 /* 243 * Polling rate when enabled is approximately 10 hz. 244 */ 245 tsleep(&vm_swapcache_sleep, 0, "csleep", hz / 10); 246 247 /* 248 * State hysteresis. Generate write activity up to 75% of 249 * swap, then clean out swap assignments down to 70%, then 250 * repeat. 251 */ 252 if (state == SWAPC_WRITING) { 253 if (vm_swap_cache_use > SWAPMAX(0)) 254 state = SWAPC_CLEANING; 255 } else { 256 if (vm_swap_cache_use < SWAPMAX(-10)) 257 state = SWAPC_WRITING; 258 } 259 260 /* 261 * We are allowed to continue accumulating burst value 262 * in either state. Allow the user to set curburst > maxburst 263 * for the initial load-in. 264 */ 265 if (vm_swapcache_curburst < vm_swapcache_maxburst) { 266 vm_swapcache_curburst += vm_swapcache_accrate / 10; 267 if (vm_swapcache_curburst > vm_swapcache_maxburst) 268 vm_swapcache_curburst = vm_swapcache_maxburst; 269 } 270 271 /* 272 * We don't want to nickle-and-dime the scan as that will 273 * create unnecessary fragmentation. The minimum burst 274 * is one-seconds worth of accumulation. 275 */ 276 if (state != SWAPC_WRITING) { 277 vm_swapcache_cleaning(&swmarker, &swindex); 278 continue; 279 } 280 if (vm_swapcache_curburst < vm_swapcache_accrate) 281 continue; 282 283 reached_end = 0; 284 count = vm_swapcache_maxlaunder / PQ_L2_SIZE + 2; 285 scount = vm_swapcache_maxscan / PQ_L2_SIZE + 2; 286 287 if (burst == SWAPB_BURSTING) { 288 if (vm_swapcache_writing_heuristic()) { 289 for (q = 0; q < PQ_L2_SIZE; ++q) { 290 reached_end += 291 vm_swapcache_writing( 292 &page_marker[q], 293 count, 294 scount); 295 } 296 } 297 if (vm_swapcache_curburst <= 0) 298 burst = SWAPB_RECOVERING; 299 } else if (vm_swapcache_curburst > vm_swapcache_minburst) { 300 if (vm_swapcache_writing_heuristic()) { 301 for (q = 0; q < PQ_L2_SIZE; ++q) { 302 reached_end += 303 vm_swapcache_writing( 304 &page_marker[q], 305 count, 306 scount); 307 } 308 } 309 burst = SWAPB_BURSTING; 310 } 311 if (reached_end == PQ_L2_SIZE) { 312 vm_swapcache_inactive_heuristic = 313 -vm_swapcache_hysteresis; 314 } 315 } 316 317 /* 318 * Cleanup (NOT REACHED) 319 */ 320 for (q = 0; q < PQ_L2_SIZE; ++q) { 321 vm_page_queues_spin_lock(PQ_INACTIVE + q); 322 TAILQ_REMOVE( 323 &vm_page_queues[PQ_INACTIVE + q].pl, 324 &page_marker[q], pageq); 325 vm_page_queues_spin_unlock(PQ_INACTIVE + q); 326 } 327 328 lwkt_gettoken(&swindex->token); 329 TAILQ_REMOVE(&swindex->list, &swmarker, object_list); 330 lwkt_reltoken(&swindex->token); 331 } 332 333 static struct kproc_desc swpc_kp = { 334 "swapcached", 335 vm_swapcached_thread, 336 &swapcached_thread 337 }; 338 SYSINIT(swapcached, SI_SUB_KTHREAD_PAGE, SI_ORDER_SECOND, kproc_start, &swpc_kp); 339 340 /* 341 * Deal with an overflow of the heuristic counter or if the user 342 * manually changes the hysteresis. 343 * 344 * Try to avoid small incremental pageouts by waiting for enough 345 * pages to buildup in the inactive queue to hopefully get a good 346 * burst in. This heuristic is bumped by the VM system and reset 347 * when our scan hits the end of the queue. 348 * 349 * Return TRUE if we need to take a writing pass. 350 */ 351 static int 352 vm_swapcache_writing_heuristic(void) 353 { 354 int hyst; 355 356 hyst = vmstats.v_inactive_count / 4; 357 if (hyst < vm_swapcache_min_hysteresis) 358 hyst = vm_swapcache_min_hysteresis; 359 cpu_ccfence(); 360 vm_swapcache_hysteresis = hyst; 361 362 if (vm_swapcache_inactive_heuristic < -hyst) 363 vm_swapcache_inactive_heuristic = -hyst; 364 365 return (vm_swapcache_inactive_heuristic >= 0); 366 } 367 368 /* 369 * Take a writing pass on one of the inactive queues, return non-zero if 370 * we hit the end of the queue. 371 */ 372 static int 373 vm_swapcache_writing(vm_page_t marker, int count, int scount) 374 { 375 vm_object_t object; 376 struct vnode *vp; 377 vm_page_t m; 378 int isblkdev; 379 380 /* 381 * Scan the inactive queue from our marker to locate 382 * suitable pages to push to the swap cache. 383 * 384 * We are looking for clean vnode-backed pages. 385 */ 386 vm_page_queues_spin_lock(marker->queue); 387 while ((m = TAILQ_NEXT(marker, pageq)) != NULL && 388 count > 0 && scount-- > 0) { 389 KKASSERT(m->queue == marker->queue); 390 391 /* 392 * Stop using swap if paniced, dumping, or dumped. 393 * Don't try to write if our curburst has been exhausted. 394 */ 395 if (panicstr || dumping) 396 break; 397 if (vm_swapcache_curburst < 0) 398 break; 399 400 /* 401 * Move marker 402 */ 403 TAILQ_REMOVE( 404 &vm_page_queues[marker->queue].pl, marker, pageq); 405 TAILQ_INSERT_AFTER( 406 &vm_page_queues[marker->queue].pl, m, marker, pageq); 407 408 /* 409 * Ignore markers and ignore pages that already have a swap 410 * assignment. 411 */ 412 if (m->flags & (PG_MARKER | PG_SWAPPED)) 413 continue; 414 if (vm_page_busy_try(m, TRUE)) 415 continue; 416 vm_page_queues_spin_unlock(marker->queue); 417 418 if ((object = m->object) == NULL) { 419 vm_page_wakeup(m); 420 vm_page_queues_spin_lock(marker->queue); 421 continue; 422 } 423 vm_object_hold(object); 424 if (m->object != object) { 425 vm_object_drop(object); 426 vm_page_wakeup(m); 427 vm_page_queues_spin_lock(marker->queue); 428 continue; 429 } 430 if (vm_swapcache_test(m)) { 431 vm_object_drop(object); 432 vm_page_wakeup(m); 433 vm_page_queues_spin_lock(marker->queue); 434 continue; 435 } 436 437 vp = object->handle; 438 if (vp == NULL) { 439 vm_object_drop(object); 440 vm_page_wakeup(m); 441 vm_page_queues_spin_lock(marker->queue); 442 continue; 443 } 444 445 switch(vp->v_type) { 446 case VREG: 447 /* 448 * PG_NOTMETA generically means 'don't swapcache this', 449 * and HAMMER will set this for regular data buffers 450 * (and leave it unset for meta-data buffers) as 451 * appropriate when double buffering is enabled. 452 */ 453 if (m->flags & PG_NOTMETA) { 454 vm_object_drop(object); 455 vm_page_wakeup(m); 456 vm_page_queues_spin_lock(marker->queue); 457 continue; 458 } 459 460 /* 461 * If data_enable is 0 do not try to swapcache data. 462 * If use_chflags is set then only swapcache data for 463 * VSWAPCACHE marked vnodes, otherwise any vnode. 464 */ 465 if (vm_swapcache_data_enable == 0 || 466 ((vp->v_flag & VSWAPCACHE) == 0 && 467 vm_swapcache_use_chflags)) { 468 vm_object_drop(object); 469 vm_page_wakeup(m); 470 vm_page_queues_spin_lock(marker->queue); 471 continue; 472 } 473 if (vm_swapcache_maxfilesize && 474 object->size > 475 (vm_swapcache_maxfilesize >> PAGE_SHIFT)) { 476 vm_object_drop(object); 477 vm_page_wakeup(m); 478 vm_page_queues_spin_lock(marker->queue); 479 continue; 480 } 481 isblkdev = 0; 482 break; 483 case VCHR: 484 /* 485 * PG_NOTMETA generically means 'don't swapcache this', 486 * and HAMMER will set this for regular data buffers 487 * (and leave it unset for meta-data buffers) as 488 * appropriate when double buffering is enabled. 489 */ 490 if (m->flags & PG_NOTMETA) { 491 vm_object_drop(object); 492 vm_page_wakeup(m); 493 vm_page_queues_spin_lock(marker->queue); 494 continue; 495 } 496 if (vm_swapcache_meta_enable == 0) { 497 vm_object_drop(object); 498 vm_page_wakeup(m); 499 vm_page_queues_spin_lock(marker->queue); 500 continue; 501 } 502 isblkdev = 1; 503 break; 504 default: 505 vm_object_drop(object); 506 vm_page_wakeup(m); 507 vm_page_queues_spin_lock(marker->queue); 508 continue; 509 } 510 511 512 /* 513 * Assign swap and initiate I/O. 514 * 515 * (adjust for the --count which also occurs in the loop) 516 */ 517 count -= vm_swapcached_flush(m, isblkdev); 518 519 /* 520 * Setup for next loop using marker. 521 */ 522 vm_object_drop(object); 523 vm_page_queues_spin_lock(marker->queue); 524 } 525 526 /* 527 * The marker could wind up at the end, which is ok. If we hit the 528 * end of the list adjust the heuristic. 529 * 530 * Earlier inactive pages that were dirty and become clean 531 * are typically moved to the end of PQ_INACTIVE by virtue 532 * of vfs_vmio_release() when they become unwired from the 533 * buffer cache. 534 */ 535 vm_page_queues_spin_unlock(marker->queue); 536 537 /* 538 * m invalid but can be used to test for NULL 539 */ 540 return (m == NULL); 541 } 542 543 /* 544 * Flush the specified page using the swap_pager. The page 545 * must be busied by the caller and its disposition will become 546 * the responsibility of this function. 547 * 548 * Try to collect surrounding pages, including pages which may 549 * have already been assigned swap. Try to cluster within a 550 * contiguous aligned SMAP_META_PAGES (typ 16 x PAGE_SIZE) block 551 * to match what swap_pager_putpages() can do. 552 * 553 * We also want to try to match against the buffer cache blocksize 554 * but we don't really know what it is here. Since the buffer cache 555 * wires and unwires pages in groups the fact that we skip wired pages 556 * should be sufficient. 557 * 558 * Returns a count of pages we might have flushed (minimum 1) 559 */ 560 static 561 int 562 vm_swapcached_flush(vm_page_t m, int isblkdev) 563 { 564 vm_object_t object; 565 vm_page_t marray[SWAP_META_PAGES]; 566 vm_pindex_t basei; 567 int rtvals[SWAP_META_PAGES]; 568 int x; 569 int i; 570 int j; 571 int count; 572 int error; 573 574 vm_page_io_start(m); 575 vm_page_protect(m, VM_PROT_READ); 576 object = m->object; 577 vm_object_hold(object); 578 579 /* 580 * Try to cluster around (m), keeping in mind that the swap pager 581 * can only do SMAP_META_PAGES worth of continguous write. 582 */ 583 x = (int)m->pindex & SWAP_META_MASK; 584 marray[x] = m; 585 basei = m->pindex; 586 vm_page_wakeup(m); 587 588 for (i = x - 1; i >= 0; --i) { 589 m = vm_page_lookup_busy_try(object, basei - x + i, 590 TRUE, &error); 591 if (error || m == NULL) 592 break; 593 if (vm_swapcache_test(m)) { 594 vm_page_wakeup(m); 595 break; 596 } 597 if (isblkdev && (m->flags & PG_NOTMETA)) { 598 vm_page_wakeup(m); 599 break; 600 } 601 vm_page_io_start(m); 602 vm_page_protect(m, VM_PROT_READ); 603 if (m->queue - m->pc == PQ_CACHE) { 604 vm_page_unqueue_nowakeup(m); 605 vm_page_deactivate(m); 606 } 607 marray[i] = m; 608 vm_page_wakeup(m); 609 } 610 ++i; 611 612 for (j = x + 1; j < SWAP_META_PAGES; ++j) { 613 m = vm_page_lookup_busy_try(object, basei - x + j, 614 TRUE, &error); 615 if (error || m == NULL) 616 break; 617 if (vm_swapcache_test(m)) { 618 vm_page_wakeup(m); 619 break; 620 } 621 if (isblkdev && (m->flags & PG_NOTMETA)) { 622 vm_page_wakeup(m); 623 break; 624 } 625 vm_page_io_start(m); 626 vm_page_protect(m, VM_PROT_READ); 627 if (m->queue - m->pc == PQ_CACHE) { 628 vm_page_unqueue_nowakeup(m); 629 vm_page_deactivate(m); 630 } 631 marray[j] = m; 632 vm_page_wakeup(m); 633 } 634 635 count = j - i; 636 vm_object_pip_add(object, count); 637 swap_pager_putpages(object, marray + i, count, FALSE, rtvals + i); 638 vm_swapcache_write_count += count * PAGE_SIZE; 639 vm_swapcache_curburst -= count * PAGE_SIZE; 640 641 while (i < j) { 642 if (rtvals[i] != VM_PAGER_PEND) { 643 vm_page_busy_wait(marray[i], FALSE, "swppgfd"); 644 vm_page_io_finish(marray[i]); 645 vm_page_wakeup(marray[i]); 646 vm_object_pip_wakeup(object); 647 } 648 ++i; 649 } 650 vm_object_drop(object); 651 return(count); 652 } 653 654 /* 655 * Test whether a VM page is suitable for writing to the swapcache. 656 * Does not test m->queue, PG_MARKER, or PG_SWAPPED. 657 * 658 * Returns 0 on success, 1 on failure 659 */ 660 static int 661 vm_swapcache_test(vm_page_t m) 662 { 663 vm_object_t object; 664 665 if (m->flags & PG_UNMANAGED) 666 return(1); 667 if (m->hold_count || m->wire_count) 668 return(1); 669 if (m->valid != VM_PAGE_BITS_ALL) 670 return(1); 671 if (m->dirty & m->valid) 672 return(1); 673 if ((object = m->object) == NULL) 674 return(1); 675 if (object->type != OBJT_VNODE || 676 (object->flags & OBJ_DEAD)) { 677 return(1); 678 } 679 vm_page_test_dirty(m); 680 if (m->dirty & m->valid) 681 return(1); 682 return(0); 683 } 684 685 /* 686 * Cleaning pass. 687 * 688 * We clean whole objects up to 16MB 689 */ 690 static 691 void 692 vm_swapcache_cleaning(vm_object_t marker, struct vm_object_hash **swindexp) 693 { 694 vm_object_t object; 695 struct vnode *vp; 696 int count; 697 int scount; 698 int n; 699 int didmove; 700 701 count = vm_swapcache_maxlaunder; 702 scount = vm_swapcache_maxscan; 703 704 /* 705 * Look for vnode objects 706 */ 707 lwkt_gettoken(&(*swindexp)->token); 708 709 didmove = 0; 710 outerloop: 711 while ((object = TAILQ_NEXT(marker, object_list)) != NULL) { 712 /* 713 * We have to skip markers. We cannot hold/drop marker 714 * objects! 715 */ 716 if (object->type == OBJT_MARKER) { 717 vm_swapcache_movemarker(marker, *swindexp, object); 718 didmove = 1; 719 continue; 720 } 721 722 /* 723 * Safety, or in case there are millions of VM objects 724 * without swapcache backing. 725 */ 726 if (--scount <= 0) 727 goto breakout; 728 729 /* 730 * We must hold the object before potentially yielding. 731 */ 732 vm_object_hold(object); 733 lwkt_yield(); 734 735 /* 736 * Only operate on live VNODE objects that are either 737 * VREG or VCHR (VCHR for meta-data). 738 */ 739 if ((object->type != OBJT_VNODE) || 740 ((object->flags & OBJ_DEAD) || 741 object->swblock_count == 0) || 742 ((vp = object->handle) == NULL) || 743 (vp->v_type != VREG && vp->v_type != VCHR)) { 744 vm_object_drop(object); 745 /* object may be invalid now */ 746 vm_swapcache_movemarker(marker, *swindexp, object); 747 didmove = 1; 748 continue; 749 } 750 751 /* 752 * Reset the object pindex stored in the marker if the 753 * working object has changed. 754 */ 755 if (marker->backing_object != object || didmove) { 756 marker->size = 0; 757 marker->backing_object_offset = 0; 758 marker->backing_object = object; 759 didmove = 0; 760 } 761 762 /* 763 * Look for swblocks starting at our iterator. 764 * 765 * The swap_pager_condfree() function attempts to free 766 * swap space starting at the specified index. The index 767 * will be updated on return. The function will return 768 * a scan factor (NOT the number of blocks freed). 769 * 770 * If it must cut its scan of the object short due to an 771 * excessive number of swblocks, or is able to free the 772 * requested number of blocks, it will return n >= count 773 * and we break and pick it back up on a future attempt. 774 * 775 * Scan the object linearly and try to batch large sets of 776 * blocks that are likely to clean out entire swap radix 777 * tree leafs. 778 */ 779 lwkt_token_swap(); 780 lwkt_reltoken(&(*swindexp)->token); 781 782 n = swap_pager_condfree(object, &marker->size, 783 (count + SWAP_META_MASK) & ~SWAP_META_MASK); 784 785 vm_object_drop(object); /* object may be invalid now */ 786 lwkt_gettoken(&(*swindexp)->token); 787 788 /* 789 * If we have exhausted the object or deleted our per-pass 790 * page limit then move us to the next object. Note that 791 * the current object may no longer be on the vm_object_list. 792 */ 793 if (n <= 0 || 794 marker->backing_object_offset > vm_swapcache_cleanperobj) { 795 vm_swapcache_movemarker(marker, *swindexp, object); 796 didmove = 1; 797 } 798 799 /* 800 * If we have exhausted our max-launder stop for now. 801 */ 802 count -= n; 803 marker->backing_object_offset += n * PAGE_SIZE; 804 if (count < 0) 805 goto breakout; 806 } 807 808 /* 809 * Iterate vm_object_lists[] hash table 810 */ 811 TAILQ_REMOVE(&(*swindexp)->list, marker, object_list); 812 lwkt_reltoken(&(*swindexp)->token); 813 if (++*swindexp >= &vm_object_hash[VMOBJ_HSIZE]) 814 *swindexp = &vm_object_hash[0]; 815 lwkt_gettoken(&(*swindexp)->token); 816 TAILQ_INSERT_HEAD(&(*swindexp)->list, marker, object_list); 817 818 if (*swindexp != &vm_object_hash[0]) 819 goto outerloop; 820 821 breakout: 822 lwkt_reltoken(&(*swindexp)->token); 823 } 824 825 /* 826 * Move the marker past the current object. Object can be stale, but we 827 * still need it to determine if the marker has to be moved. If the object 828 * is still the 'current object' (object after the marker), we hop-scotch 829 * the marker past it. 830 */ 831 static void 832 vm_swapcache_movemarker(vm_object_t marker, struct vm_object_hash *swindex, 833 vm_object_t object) 834 { 835 if (TAILQ_NEXT(marker, object_list) == object) { 836 TAILQ_REMOVE(&swindex->list, marker, object_list); 837 TAILQ_INSERT_AFTER(&swindex->list, object, marker, object_list); 838 } 839 } 840