1 /*
2 * (MPSAFE)
3 *
4 * Copyright (c) 2010,2019 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 <sys/param.h>
55 #include <sys/systm.h>
56 #include <sys/kernel.h>
57 #include <sys/proc.h>
58 #include <sys/kthread.h>
59 #include <sys/resourcevar.h>
60 #include <sys/signalvar.h>
61 #include <sys/vnode.h>
62 #include <sys/vmmeter.h>
63 #include <sys/sysctl.h>
64 #include <sys/eventhandler.h>
65
66 #include <vm/vm.h>
67 #include <vm/vm_param.h>
68 #include <sys/lock.h>
69 #include <vm/vm_object.h>
70 #include <vm/vm_page.h>
71 #include <vm/vm_map.h>
72 #include <vm/vm_pageout.h>
73 #include <vm/vm_pager.h>
74 #include <vm/swap_pager.h>
75 #include <vm/vm_extern.h>
76
77 #include <sys/spinlock2.h>
78 #include <vm/vm_page2.h>
79
80 struct swmarker {
81 struct vm_object dummy_obj;
82 struct vm_object *save_obj;
83 vm_ooffset_t save_off;
84 };
85
86 typedef struct swmarker swmarker_t;
87
88 /* the kernel process "vm_pageout"*/
89 static int vm_swapcached_flush (vm_page_t m, int isblkdev);
90 static int vm_swapcache_test(vm_page_t m);
91 static int vm_swapcache_writing_heuristic(void);
92 static int vm_swapcache_writing(vm_page_t marker, int count, int scount);
93 static void vm_swapcache_cleaning(swmarker_t *marker,
94 struct vm_object_hash **swindexp);
95 static void vm_swapcache_movemarker(swmarker_t *marker,
96 struct vm_object_hash *swindex, vm_object_t object);
97 struct thread *swapcached_thread;
98
99 SYSCTL_NODE(_vm, OID_AUTO, swapcache, CTLFLAG_RW, NULL, NULL);
100
101 int vm_swapcache_read_enable;
102 static long vm_swapcache_wtrigger;
103 static int vm_swapcache_sleep;
104 static int vm_swapcache_maxscan = PQ_L2_SIZE * 8;
105 static int vm_swapcache_maxlaunder = PQ_L2_SIZE * 4;
106 static int vm_swapcache_data_enable = 0;
107 static int vm_swapcache_meta_enable = 0;
108 static int vm_swapcache_maxswappct = 75;
109 static int vm_swapcache_hysteresis;
110 static int vm_swapcache_min_hysteresis;
111 int vm_swapcache_use_chflags = 0; /* require chflags cache */
112 static int64_t vm_swapcache_minburst = 10000000LL; /* 10MB */
113 static int64_t vm_swapcache_curburst = 4000000000LL; /* 4G after boot */
114 static int64_t vm_swapcache_maxburst = 2000000000LL; /* 2G nominal max */
115 static int64_t vm_swapcache_accrate = 100000LL; /* 100K/s */
116 static int64_t vm_swapcache_write_count;
117 static int64_t vm_swapcache_maxfilesize;
118 static int64_t vm_swapcache_cleanperobj = 16*1024*1024;
119
120 SYSCTL_INT(_vm_swapcache, OID_AUTO, maxlaunder,
121 CTLFLAG_RW, &vm_swapcache_maxlaunder, 0, "");
122 SYSCTL_INT(_vm_swapcache, OID_AUTO, maxscan,
123 CTLFLAG_RW, &vm_swapcache_maxscan, 0, "");
124
125 SYSCTL_INT(_vm_swapcache, OID_AUTO, data_enable,
126 CTLFLAG_RW, &vm_swapcache_data_enable, 0, "");
127 SYSCTL_INT(_vm_swapcache, OID_AUTO, meta_enable,
128 CTLFLAG_RW, &vm_swapcache_meta_enable, 0, "");
129 SYSCTL_INT(_vm_swapcache, OID_AUTO, read_enable,
130 CTLFLAG_RW, &vm_swapcache_read_enable, 0, "");
131 SYSCTL_INT(_vm_swapcache, OID_AUTO, maxswappct,
132 CTLFLAG_RW, &vm_swapcache_maxswappct, 0, "");
133 SYSCTL_INT(_vm_swapcache, OID_AUTO, hysteresis,
134 CTLFLAG_RD, &vm_swapcache_hysteresis, 0, "");
135 SYSCTL_INT(_vm_swapcache, OID_AUTO, min_hysteresis,
136 CTLFLAG_RW, &vm_swapcache_min_hysteresis, 0, "");
137 SYSCTL_INT(_vm_swapcache, OID_AUTO, use_chflags,
138 CTLFLAG_RW, &vm_swapcache_use_chflags, 0, "");
139
140 SYSCTL_QUAD(_vm_swapcache, OID_AUTO, minburst,
141 CTLFLAG_RW, &vm_swapcache_minburst, 0, "");
142 SYSCTL_QUAD(_vm_swapcache, OID_AUTO, curburst,
143 CTLFLAG_RW, &vm_swapcache_curburst, 0, "");
144 SYSCTL_QUAD(_vm_swapcache, OID_AUTO, maxburst,
145 CTLFLAG_RW, &vm_swapcache_maxburst, 0, "");
146 SYSCTL_QUAD(_vm_swapcache, OID_AUTO, maxfilesize,
147 CTLFLAG_RW, &vm_swapcache_maxfilesize, 0, "");
148 SYSCTL_QUAD(_vm_swapcache, OID_AUTO, accrate,
149 CTLFLAG_RW, &vm_swapcache_accrate, 0, "");
150 SYSCTL_QUAD(_vm_swapcache, OID_AUTO, write_count,
151 CTLFLAG_RW, &vm_swapcache_write_count, 0, "");
152 SYSCTL_QUAD(_vm_swapcache, OID_AUTO, cleanperobj,
153 CTLFLAG_RW, &vm_swapcache_cleanperobj, 0, "");
154
155 #define SWAPMAX(adj) \
156 ((int64_t)vm_swap_max * (vm_swapcache_maxswappct + (adj)) / 100)
157
158 /*
159 * When shutting down the machine we want to stop swapcache operation
160 * immediately so swap is not accessed after devices have been shuttered.
161 */
162 static void
shutdown_swapcache(void * arg __unused)163 shutdown_swapcache(void *arg __unused)
164 {
165 vm_swapcache_read_enable = 0;
166 vm_swapcache_data_enable = 0;
167 vm_swapcache_meta_enable = 0;
168 wakeup(&vm_swapcache_sleep); /* shortcut 5-second wait */
169 }
170
171 /*
172 * vm_swapcached is the high level pageout daemon.
173 *
174 * No requirements.
175 */
176 static void
vm_swapcached_thread(void)177 vm_swapcached_thread(void)
178 {
179 enum { SWAPC_WRITING, SWAPC_CLEANING } state = SWAPC_WRITING;
180 enum { SWAPB_BURSTING, SWAPB_RECOVERING } burst = SWAPB_BURSTING;
181 static struct vm_page page_marker[PQ_L2_SIZE];
182 static swmarker_t swmarker;
183 static struct vm_object_hash *swindex;
184 int q;
185
186 /*
187 * Thread setup
188 */
189 curthread->td_flags |= TDF_SYSTHREAD;
190 EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_kproc,
191 swapcached_thread, SHUTDOWN_PRI_FIRST);
192 EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_swapcache,
193 NULL, SHUTDOWN_PRI_SECOND);
194
195 /*
196 * Initialize our marker for the inactive scan (SWAPC_WRITING)
197 */
198 bzero(&page_marker, sizeof(page_marker));
199 for (q = 0; q < PQ_L2_SIZE; ++q) {
200 page_marker[q].flags = PG_FICTITIOUS | PG_MARKER;
201 page_marker[q].busy_count = PBUSY_LOCKED;
202 page_marker[q].queue = PQ_INACTIVE + q;
203 page_marker[q].pc = q;
204 page_marker[q].wire_count = 1;
205 vm_page_queues_spin_lock(PQ_INACTIVE + q);
206 TAILQ_INSERT_HEAD(
207 &vm_page_queues[PQ_INACTIVE + q].pl,
208 &page_marker[q], pageq);
209 vm_page_queues_spin_unlock(PQ_INACTIVE + q);
210 }
211
212 vm_swapcache_min_hysteresis = 1024;
213 vm_swapcache_hysteresis = vm_swapcache_min_hysteresis;
214 vm_swapcache_wtrigger = -vm_swapcache_hysteresis;
215
216 /*
217 * Initialize our marker for the vm_object scan (SWAPC_CLEANING)
218 */
219 bzero(&swmarker, sizeof(swmarker));
220 swmarker.dummy_obj.type = OBJT_MARKER;
221 swindex = &vm_object_hash[0];
222 lwkt_gettoken(&swindex->token);
223 TAILQ_INSERT_HEAD(&swindex->list, &swmarker.dummy_obj, object_entry);
224 lwkt_reltoken(&swindex->token);
225
226 for (;;) {
227 int reached_end;
228 int scount;
229 int count;
230
231 /*
232 * Handle shutdown
233 */
234 kproc_suspend_loop();
235
236 /*
237 * Check every 5 seconds when not enabled or if no swap
238 * is present.
239 */
240 if ((vm_swapcache_data_enable == 0 &&
241 vm_swapcache_meta_enable == 0 &&
242 vm_swap_cache_use <= SWAPMAX(0)) ||
243 vm_swap_max == 0) {
244 tsleep(&vm_swapcache_sleep, 0, "csleep", hz * 5);
245 continue;
246 }
247
248 /*
249 * Polling rate when enabled is approximately 10 hz.
250 */
251 tsleep(&vm_swapcache_sleep, 0, "csleep", hz / 10);
252
253 /*
254 * State hysteresis. Generate write activity up to 75% of
255 * swap, then clean out swap assignments down to 70%, then
256 * repeat.
257 */
258 if (state == SWAPC_WRITING) {
259 if (vm_swap_cache_use > SWAPMAX(0))
260 state = SWAPC_CLEANING;
261 } else {
262 if (vm_swap_cache_use < SWAPMAX(-10))
263 state = SWAPC_WRITING;
264 }
265
266 /*
267 * We are allowed to continue accumulating burst value
268 * in either state. Allow the user to set curburst > maxburst
269 * for the initial load-in.
270 */
271 if (vm_swapcache_curburst < vm_swapcache_maxburst) {
272 vm_swapcache_curburst += vm_swapcache_accrate / 10;
273 if (vm_swapcache_curburst > vm_swapcache_maxburst)
274 vm_swapcache_curburst = vm_swapcache_maxburst;
275 }
276
277 /*
278 * We don't want to nickle-and-dime the scan as that will
279 * create unnecessary fragmentation. The minimum burst
280 * is one-seconds worth of accumulation.
281 */
282 if (state != SWAPC_WRITING) {
283 vm_swapcache_cleaning(&swmarker, &swindex);
284 continue;
285 }
286 if (vm_swapcache_curburst < vm_swapcache_accrate)
287 continue;
288
289 reached_end = 0;
290 count = vm_swapcache_maxlaunder / PQ_L2_SIZE + 2;
291 scount = vm_swapcache_maxscan / PQ_L2_SIZE + 2;
292
293 if (burst == SWAPB_BURSTING) {
294 if (vm_swapcache_writing_heuristic()) {
295 for (q = 0; q < PQ_L2_SIZE; ++q) {
296 reached_end +=
297 vm_swapcache_writing(
298 &page_marker[q],
299 count,
300 scount);
301 }
302 }
303 if (vm_swapcache_curburst <= 0)
304 burst = SWAPB_RECOVERING;
305 } else if (vm_swapcache_curburst > vm_swapcache_minburst) {
306 if (vm_swapcache_writing_heuristic()) {
307 for (q = 0; q < PQ_L2_SIZE; ++q) {
308 reached_end +=
309 vm_swapcache_writing(
310 &page_marker[q],
311 count,
312 scount);
313 }
314 }
315 burst = SWAPB_BURSTING;
316 }
317 if (reached_end == PQ_L2_SIZE) {
318 vm_swapcache_wtrigger = -vm_swapcache_hysteresis;
319 }
320 }
321
322 /*
323 * Cleanup (NOT REACHED)
324 */
325 for (q = 0; q < PQ_L2_SIZE; ++q) {
326 vm_page_queues_spin_lock(PQ_INACTIVE + q);
327 TAILQ_REMOVE(
328 &vm_page_queues[PQ_INACTIVE + q].pl,
329 &page_marker[q], pageq);
330 vm_page_queues_spin_unlock(PQ_INACTIVE + q);
331 }
332
333 lwkt_gettoken(&swindex->token);
334 TAILQ_REMOVE(&swindex->list, &swmarker.dummy_obj, object_entry);
335 lwkt_reltoken(&swindex->token);
336 }
337
338 static struct kproc_desc swpc_kp = {
339 "swapcached",
340 vm_swapcached_thread,
341 &swapcached_thread
342 };
343 SYSINIT(swapcached, SI_SUB_KTHREAD_PAGE, SI_ORDER_SECOND, kproc_start, &swpc_kp);
344
345 /*
346 * Deal with an overflow of the heuristic counter or if the user
347 * manually changes the hysteresis.
348 *
349 * Try to avoid small incremental pageouts by waiting for enough
350 * pages to buildup in the inactive queue to hopefully get a good
351 * burst in. This heuristic is bumped by the VM system and reset
352 * when our scan hits the end of the queue.
353 *
354 * Return TRUE if we need to take a writing pass.
355 */
356 static int
vm_swapcache_writing_heuristic(void)357 vm_swapcache_writing_heuristic(void)
358 {
359 int hyst;
360 int q;
361 long adds;
362
363 hyst = vmstats.v_inactive_count / 4;
364 if (hyst < vm_swapcache_min_hysteresis)
365 hyst = vm_swapcache_min_hysteresis;
366 cpu_ccfence();
367 vm_swapcache_hysteresis = hyst;
368
369 adds = 0;
370 for (q = PQ_INACTIVE; q < PQ_INACTIVE + PQ_L2_SIZE; ++q) {
371 adds += atomic_swap_long(&vm_page_queues[q].adds, 0);
372 }
373 vm_swapcache_wtrigger += adds;
374 if (vm_swapcache_wtrigger < -hyst)
375 vm_swapcache_wtrigger = -hyst;
376 return (vm_swapcache_wtrigger >= 0);
377 }
378
379 /*
380 * Take a writing pass on one of the inactive queues, return non-zero if
381 * we hit the end of the queue.
382 */
383 static int
vm_swapcache_writing(vm_page_t marker,int count,int scount)384 vm_swapcache_writing(vm_page_t marker, int count, int scount)
385 {
386 vm_object_t object;
387 struct vnode *vp;
388 vm_page_t m;
389 int isblkdev;
390
391 /*
392 * Scan the inactive queue from our marker to locate
393 * suitable pages to push to the swap cache.
394 *
395 * We are looking for clean vnode-backed pages.
396 */
397 vm_page_queues_spin_lock(marker->queue);
398 while ((m = TAILQ_NEXT(marker, pageq)) != NULL &&
399 count > 0 && scount-- > 0) {
400 KKASSERT(m->queue == marker->queue);
401
402 /*
403 * Stop using swap if paniced, dumping, or dumped.
404 * Don't try to write if our curburst has been exhausted.
405 */
406 if (panicstr || dumping)
407 break;
408 if (vm_swapcache_curburst < 0)
409 break;
410
411 /*
412 * Move marker
413 */
414 TAILQ_REMOVE(
415 &vm_page_queues[marker->queue].pl, marker, pageq);
416 TAILQ_INSERT_AFTER(
417 &vm_page_queues[marker->queue].pl, m, marker, pageq);
418
419 /*
420 * Ignore markers and ignore pages that already have a swap
421 * assignment.
422 */
423 if (m->flags & (PG_MARKER | PG_SWAPPED))
424 continue;
425 if (vm_page_busy_try(m, TRUE))
426 continue;
427 vm_page_queues_spin_unlock(marker->queue);
428
429 if ((object = m->object) == NULL) {
430 vm_page_wakeup(m);
431 vm_page_queues_spin_lock(marker->queue);
432 continue;
433 }
434 vm_object_hold(object);
435 if (m->object != object) {
436 vm_object_drop(object);
437 vm_page_wakeup(m);
438 vm_page_queues_spin_lock(marker->queue);
439 continue;
440 }
441 if (vm_swapcache_test(m)) {
442 vm_object_drop(object);
443 vm_page_wakeup(m);
444 vm_page_queues_spin_lock(marker->queue);
445 continue;
446 }
447
448 vp = object->handle;
449 if (vp == NULL) {
450 vm_object_drop(object);
451 vm_page_wakeup(m);
452 vm_page_queues_spin_lock(marker->queue);
453 continue;
454 }
455
456 switch(vp->v_type) {
457 case VREG:
458 /*
459 * PG_NOTMETA generically means 'don't swapcache this',
460 * and HAMMER will set this for regular data buffers
461 * (and leave it unset for meta-data buffers) as
462 * appropriate when double buffering is enabled.
463 */
464 if (m->flags & PG_NOTMETA) {
465 vm_object_drop(object);
466 vm_page_wakeup(m);
467 vm_page_queues_spin_lock(marker->queue);
468 continue;
469 }
470
471 /*
472 * If data_enable is 0 do not try to swapcache data.
473 * If use_chflags is set then only swapcache data for
474 * VSWAPCACHE marked vnodes, otherwise any vnode.
475 */
476 if (vm_swapcache_data_enable == 0 ||
477 ((vp->v_flag & VSWAPCACHE) == 0 &&
478 vm_swapcache_use_chflags)) {
479 vm_object_drop(object);
480 vm_page_wakeup(m);
481 vm_page_queues_spin_lock(marker->queue);
482 continue;
483 }
484 if (vm_swapcache_maxfilesize &&
485 object->size >
486 (vm_swapcache_maxfilesize >> PAGE_SHIFT)) {
487 vm_object_drop(object);
488 vm_page_wakeup(m);
489 vm_page_queues_spin_lock(marker->queue);
490 continue;
491 }
492 isblkdev = 0;
493 break;
494 case VCHR:
495 /*
496 * PG_NOTMETA generically means 'don't swapcache this',
497 * and HAMMER will set this for regular data buffers
498 * (and leave it unset for meta-data buffers) as
499 * appropriate when double buffering is enabled.
500 */
501 if (m->flags & PG_NOTMETA) {
502 vm_object_drop(object);
503 vm_page_wakeup(m);
504 vm_page_queues_spin_lock(marker->queue);
505 continue;
506 }
507 if (vm_swapcache_meta_enable == 0) {
508 vm_object_drop(object);
509 vm_page_wakeup(m);
510 vm_page_queues_spin_lock(marker->queue);
511 continue;
512 }
513 isblkdev = 1;
514 break;
515 default:
516 vm_object_drop(object);
517 vm_page_wakeup(m);
518 vm_page_queues_spin_lock(marker->queue);
519 continue;
520 }
521
522
523 /*
524 * Assign swap and initiate I/O.
525 *
526 * (adjust for the --count which also occurs in the loop)
527 */
528 count -= vm_swapcached_flush(m, isblkdev);
529
530 /*
531 * Setup for next loop using marker.
532 */
533 vm_object_drop(object);
534 vm_page_queues_spin_lock(marker->queue);
535 }
536
537 /*
538 * The marker could wind up at the end, which is ok. If we hit the
539 * end of the list adjust the heuristic.
540 *
541 * Earlier inactive pages that were dirty and become clean
542 * are typically moved to the end of PQ_INACTIVE by virtue
543 * of vfs_vmio_release() when they become unwired from the
544 * buffer cache.
545 */
546 vm_page_queues_spin_unlock(marker->queue);
547
548 /*
549 * m invalid but can be used to test for NULL
550 */
551 return (m == NULL);
552 }
553
554 /*
555 * Flush the specified page using the swap_pager. The page
556 * must be busied by the caller and its disposition will become
557 * the responsibility of this function.
558 *
559 * Try to collect surrounding pages, including pages which may
560 * have already been assigned swap. Try to cluster within a
561 * contiguous aligned SMAP_META_PAGES (typ 16 x PAGE_SIZE) block
562 * to match what swap_pager_putpages() can do.
563 *
564 * We also want to try to match against the buffer cache blocksize
565 * but we don't really know what it is here. Since the buffer cache
566 * wires and unwires pages in groups the fact that we skip wired pages
567 * should be sufficient.
568 *
569 * Returns a count of pages we might have flushed (minimum 1)
570 */
571 static
572 int
vm_swapcached_flush(vm_page_t m,int isblkdev)573 vm_swapcached_flush(vm_page_t m, int isblkdev)
574 {
575 vm_object_t object;
576 vm_page_t marray[SWAP_META_PAGES];
577 vm_pindex_t basei;
578 int rtvals[SWAP_META_PAGES];
579 int x;
580 int i;
581 int j;
582 int count;
583 int error;
584
585 vm_page_io_start(m);
586 vm_page_protect(m, VM_PROT_READ);
587 object = m->object;
588 vm_object_hold(object);
589
590 /*
591 * Try to cluster around (m), keeping in mind that the swap pager
592 * can only do SMAP_META_PAGES worth of continguous write.
593 */
594 x = (int)m->pindex & SWAP_META_MASK;
595 marray[x] = m;
596 basei = m->pindex;
597 vm_page_wakeup(m);
598
599 for (i = x - 1; i >= 0; --i) {
600 m = vm_page_lookup_busy_try(object, basei - x + i,
601 TRUE, &error);
602 if (error || m == NULL)
603 break;
604 if (vm_swapcache_test(m)) {
605 vm_page_wakeup(m);
606 break;
607 }
608 if (isblkdev && (m->flags & PG_NOTMETA)) {
609 vm_page_wakeup(m);
610 break;
611 }
612 vm_page_io_start(m);
613 vm_page_protect(m, VM_PROT_READ);
614 if (m->queue - m->pc == PQ_CACHE) {
615 vm_page_unqueue_nowakeup(m);
616 vm_page_deactivate(m);
617 }
618 marray[i] = m;
619 vm_page_wakeup(m);
620 }
621 ++i;
622
623 for (j = x + 1; j < SWAP_META_PAGES; ++j) {
624 m = vm_page_lookup_busy_try(object, basei - x + j,
625 TRUE, &error);
626 if (error || m == NULL)
627 break;
628 if (vm_swapcache_test(m)) {
629 vm_page_wakeup(m);
630 break;
631 }
632 if (isblkdev && (m->flags & PG_NOTMETA)) {
633 vm_page_wakeup(m);
634 break;
635 }
636 vm_page_io_start(m);
637 vm_page_protect(m, VM_PROT_READ);
638 if (m->queue - m->pc == PQ_CACHE) {
639 vm_page_unqueue_nowakeup(m);
640 vm_page_deactivate(m);
641 }
642 marray[j] = m;
643 vm_page_wakeup(m);
644 }
645
646 count = j - i;
647 vm_object_pip_add(object, count);
648 swap_pager_putpages(object, marray + i, count, FALSE, rtvals + i);
649 vm_swapcache_write_count += count * PAGE_SIZE;
650 vm_swapcache_curburst -= count * PAGE_SIZE;
651
652 while (i < j) {
653 if (rtvals[i] != VM_PAGER_PEND) {
654 vm_page_busy_wait(marray[i], FALSE, "swppgfd");
655 vm_page_io_finish(marray[i]);
656 vm_page_wakeup(marray[i]);
657 vm_object_pip_wakeup(object);
658 }
659 ++i;
660 }
661 vm_object_drop(object);
662 return(count);
663 }
664
665 /*
666 * Test whether a VM page is suitable for writing to the swapcache.
667 * Does not test m->queue, PG_MARKER, or PG_SWAPPED.
668 *
669 * Returns 0 on success, 1 on failure
670 */
671 static int
vm_swapcache_test(vm_page_t m)672 vm_swapcache_test(vm_page_t m)
673 {
674 vm_object_t object;
675
676 if (m->flags & (PG_UNQUEUED | PG_FICTITIOUS))
677 return(1);
678 if (m->hold_count || m->wire_count)
679 return(1);
680 if (m->valid != VM_PAGE_BITS_ALL)
681 return(1);
682 if (m->dirty & m->valid)
683 return(1);
684 if ((object = m->object) == NULL)
685 return(1);
686 if (object->type != OBJT_VNODE ||
687 (object->flags & OBJ_DEAD)) {
688 return(1);
689 }
690 vm_page_test_dirty(m);
691 if (m->dirty & m->valid)
692 return(1);
693 return(0);
694 }
695
696 /*
697 * Cleaning pass.
698 *
699 * We clean whole objects up to 16MB
700 */
701 static
702 void
vm_swapcache_cleaning(swmarker_t * marker,struct vm_object_hash ** swindexp)703 vm_swapcache_cleaning(swmarker_t *marker, struct vm_object_hash **swindexp)
704 {
705 vm_object_t object;
706 struct vnode *vp;
707 int count;
708 int scount;
709 int n;
710 int didmove;
711
712 count = vm_swapcache_maxlaunder;
713 scount = vm_swapcache_maxscan;
714
715 /*
716 * Look for vnode objects
717 */
718 lwkt_gettoken(&(*swindexp)->token);
719
720 didmove = 0;
721 outerloop:
722 while ((object = TAILQ_NEXT(&marker->dummy_obj,
723 object_entry)) != NULL) {
724 /*
725 * We have to skip markers. We cannot hold/drop marker
726 * objects!
727 */
728 if (object->type == OBJT_MARKER) {
729 vm_swapcache_movemarker(marker, *swindexp, object);
730 didmove = 1;
731 continue;
732 }
733
734 /*
735 * Safety, or in case there are millions of VM objects
736 * without swapcache backing.
737 */
738 if (--scount <= 0)
739 goto breakout;
740
741 /*
742 * We must hold the object before potentially yielding.
743 */
744 vm_object_hold(object);
745 lwkt_yield();
746
747 /*
748 * Only operate on live VNODE objects that are either
749 * VREG or VCHR (VCHR for meta-data).
750 */
751 if ((object->type != OBJT_VNODE) ||
752 ((object->flags & OBJ_DEAD) ||
753 object->swblock_count == 0) ||
754 ((vp = object->handle) == NULL) ||
755 (vp->v_type != VREG && vp->v_type != VCHR)) {
756 vm_object_drop(object);
757 /* object may be invalid now */
758 vm_swapcache_movemarker(marker, *swindexp, object);
759 didmove = 1;
760 continue;
761 }
762
763 /*
764 * Reset the object pindex stored in the marker if the
765 * working object has changed.
766 */
767 if (marker->save_obj != object || didmove) {
768 marker->dummy_obj.size = 0;
769 marker->save_off = 0;
770 marker->save_obj = object;
771 didmove = 0;
772 }
773
774 /*
775 * Look for swblocks starting at our iterator.
776 *
777 * The swap_pager_condfree() function attempts to free
778 * swap space starting at the specified index. The index
779 * will be updated on return. The function will return
780 * a scan factor (NOT the number of blocks freed).
781 *
782 * If it must cut its scan of the object short due to an
783 * excessive number of swblocks, or is able to free the
784 * requested number of blocks, it will return n >= count
785 * and we break and pick it back up on a future attempt.
786 *
787 * Scan the object linearly and try to batch large sets of
788 * blocks that are likely to clean out entire swap radix
789 * tree leafs.
790 */
791 lwkt_token_swap();
792 lwkt_reltoken(&(*swindexp)->token);
793
794 n = swap_pager_condfree(object, &marker->dummy_obj.size,
795 (count + SWAP_META_MASK) & ~SWAP_META_MASK);
796
797 vm_object_drop(object); /* object may be invalid now */
798 lwkt_gettoken(&(*swindexp)->token);
799
800 /*
801 * If we have exhausted the object or deleted our per-pass
802 * page limit then move us to the next object. Note that
803 * the current object may no longer be on the vm_object_entry.
804 */
805 if (n <= 0 ||
806 marker->save_off > vm_swapcache_cleanperobj) {
807 vm_swapcache_movemarker(marker, *swindexp, object);
808 didmove = 1;
809 }
810
811 /*
812 * If we have exhausted our max-launder stop for now.
813 */
814 count -= n;
815 marker->save_off += n * PAGE_SIZE;
816 if (count < 0)
817 goto breakout;
818 }
819
820 /*
821 * Iterate vm_object_hash[] hash table
822 */
823 TAILQ_REMOVE(&(*swindexp)->list, &marker->dummy_obj, object_entry);
824 lwkt_reltoken(&(*swindexp)->token);
825 if (++*swindexp >= &vm_object_hash[VMOBJ_HSIZE])
826 *swindexp = &vm_object_hash[0];
827 lwkt_gettoken(&(*swindexp)->token);
828 TAILQ_INSERT_HEAD(&(*swindexp)->list, &marker->dummy_obj, object_entry);
829
830 if (*swindexp != &vm_object_hash[0])
831 goto outerloop;
832
833 breakout:
834 lwkt_reltoken(&(*swindexp)->token);
835 }
836
837 /*
838 * Move the marker past the current object. Object can be stale, but we
839 * still need it to determine if the marker has to be moved. If the object
840 * is still the 'current object' (object after the marker), we hop-scotch
841 * the marker past it.
842 */
843 static void
vm_swapcache_movemarker(swmarker_t * marker,struct vm_object_hash * swindex,vm_object_t object)844 vm_swapcache_movemarker(swmarker_t *marker, struct vm_object_hash *swindex,
845 vm_object_t object)
846 {
847 if (TAILQ_NEXT(&marker->dummy_obj, object_entry) == object) {
848 TAILQ_REMOVE(&swindex->list, &marker->dummy_obj, object_entry);
849 TAILQ_INSERT_AFTER(&swindex->list, object,
850 &marker->dummy_obj, object_entry);
851 }
852 }
853