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7 * it under the terms of the GNU General Public License version 2 only,
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10 * This program is distributed in the hope that it will be useful, but
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13 * General Public License version 2 for more details (a copy is included
14 * in the LICENSE file that accompanied this code).
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18 * http://www.gnu.org/licenses/gpl-2.0.html
23 * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
24 * Use is subject to license terms.
26 * Copyright (c) 2011, 2015, Intel Corporation.
29 * This file is part of Lustre, http://www.lustre.org/
30 * Lustre is a trademark of Sun Microsystems, Inc.
32 * Implementation of cl_page for OSC layer.
34 * Author: Nikita Danilov <nikita.danilov@sun.com>
35 * Author: Jinshan Xiong <jinshan.xiong@intel.com>
38 #define DEBUG_SUBSYSTEM S_OSC
40 #include "osc_cl_internal.h"
42 static void osc_lru_del(struct client_obd *cli, struct osc_page *opg);
43 static void osc_lru_use(struct client_obd *cli, struct osc_page *opg);
44 static int osc_lru_alloc(const struct lu_env *env, struct client_obd *cli,
45 struct osc_page *opg);
54 static void osc_page_transfer_get(struct osc_page *opg, const char *label)
56 struct cl_page *page = opg->ops_cl.cpl_page;
58 LASSERT(!opg->ops_transfer_pinned);
60 lu_ref_add_atomic(&page->cp_reference, label, page);
61 opg->ops_transfer_pinned = 1;
64 static void osc_page_transfer_put(const struct lu_env *env,
67 struct cl_page *page = opg->ops_cl.cpl_page;
69 if (opg->ops_transfer_pinned) {
70 opg->ops_transfer_pinned = 0;
71 lu_ref_del(&page->cp_reference, "transfer", page);
72 cl_page_put(env, page);
77 * This is called once for every page when it is submitted for a transfer
78 * either opportunistic (osc_page_cache_add()), or immediate
79 * (osc_page_submit()).
81 static void osc_page_transfer_add(const struct lu_env *env,
82 struct osc_page *opg, enum cl_req_type crt)
84 struct osc_object *obj = cl2osc(opg->ops_cl.cpl_obj);
86 /* ops_lru and ops_inflight share the same field, so take it from LRU
87 * first and then use it as inflight. */
88 osc_lru_use(osc_cli(obj), opg);
91 int osc_page_cache_add(const struct lu_env *env,
92 const struct cl_page_slice *slice, struct cl_io *io)
94 struct osc_page *opg = cl2osc_page(slice);
98 osc_page_transfer_get(opg, "transfer\0cache");
99 result = osc_queue_async_io(env, io, opg);
101 osc_page_transfer_put(env, opg);
103 osc_page_transfer_add(env, opg, CRT_WRITE);
108 void osc_index2policy(union ldlm_policy_data *policy,
109 const struct cl_object *obj, pgoff_t start, pgoff_t end)
111 memset(policy, 0, sizeof *policy);
112 policy->l_extent.start = cl_offset(obj, start);
113 policy->l_extent.end = cl_offset(obj, end + 1) - 1;
116 static const char *osc_list(struct list_head *head)
118 return list_empty(head) ? "-" : "+";
121 static inline cfs_time_t osc_submit_duration(struct osc_page *opg)
123 if (opg->ops_submit_time == 0)
126 return (cfs_time_current() - opg->ops_submit_time);
129 static int osc_page_print(const struct lu_env *env,
130 const struct cl_page_slice *slice,
131 void *cookie, lu_printer_t printer)
133 struct osc_page *opg = cl2osc_page(slice);
134 struct osc_async_page *oap = &opg->ops_oap;
135 struct osc_object *obj = cl2osc(slice->cpl_obj);
136 struct client_obd *cli = &osc_export(obj)->exp_obd->u.cli;
138 return (*printer)(env, cookie, LUSTRE_OSC_NAME"-page@%p %lu: "
139 "1< %#x %d %u %s %s > "
140 "2< %lld %u %u %#x %#x | %p %p %p > "
142 "4< %d %d %d %lu %s | %s %s %s %s > "
143 "5< %s %s %s %s | %d %s | %d %s %s>\n",
146 oap->oap_magic, oap->oap_cmd,
147 oap->oap_interrupted,
148 osc_list(&oap->oap_pending_item),
149 osc_list(&oap->oap_rpc_item),
151 oap->oap_obj_off, oap->oap_page_off, oap->oap_count,
152 oap->oap_async_flags, oap->oap_brw_flags,
153 oap->oap_request, oap->oap_cli, obj,
155 opg->ops_transfer_pinned,
156 osc_submit_duration(opg), opg->ops_srvlock,
158 cli->cl_r_in_flight, cli->cl_w_in_flight,
159 cli->cl_max_rpcs_in_flight,
161 osc_list(&cli->cl_cache_waiters),
162 osc_list(&cli->cl_loi_ready_list),
163 osc_list(&cli->cl_loi_hp_ready_list),
164 osc_list(&cli->cl_loi_write_list),
165 osc_list(&cli->cl_loi_read_list),
167 osc_list(&obj->oo_ready_item),
168 osc_list(&obj->oo_hp_ready_item),
169 osc_list(&obj->oo_write_item),
170 osc_list(&obj->oo_read_item),
171 atomic_read(&obj->oo_nr_reads),
172 osc_list(&obj->oo_reading_exts),
173 atomic_read(&obj->oo_nr_writes),
174 osc_list(&obj->oo_hp_exts),
175 osc_list(&obj->oo_urgent_exts));
178 static void osc_page_delete(const struct lu_env *env,
179 const struct cl_page_slice *slice)
181 struct osc_page *opg = cl2osc_page(slice);
182 struct osc_object *obj = cl2osc(opg->ops_cl.cpl_obj);
186 CDEBUG(D_TRACE, "%p\n", opg);
187 osc_page_transfer_put(env, opg);
188 rc = osc_teardown_async_page(env, obj, opg);
190 CL_PAGE_DEBUG(D_ERROR, env, slice->cpl_page,
191 "Trying to teardown failed: %d\n", rc);
195 osc_lru_del(osc_cli(obj), opg);
197 if (slice->cpl_page->cp_type == CPT_CACHEABLE) {
200 spin_lock(&obj->oo_tree_lock);
201 value = radix_tree_delete(&obj->oo_tree, osc_index(opg));
204 spin_unlock(&obj->oo_tree_lock);
206 LASSERT(ergo(value != NULL, value == opg));
212 static void osc_page_clip(const struct lu_env *env,
213 const struct cl_page_slice *slice,
216 struct osc_page *opg = cl2osc_page(slice);
217 struct osc_async_page *oap = &opg->ops_oap;
219 opg->ops_from = from;
221 spin_lock(&oap->oap_lock);
222 oap->oap_async_flags |= ASYNC_COUNT_STABLE;
223 spin_unlock(&oap->oap_lock);
226 static int osc_page_cancel(const struct lu_env *env,
227 const struct cl_page_slice *slice)
229 struct osc_page *opg = cl2osc_page(slice);
232 /* Check if the transferring against this page
233 * is completed, or not even queued. */
234 if (opg->ops_transfer_pinned)
235 /* FIXME: may not be interrupted.. */
236 rc = osc_cancel_async_page(env, opg);
237 LASSERT(ergo(rc == 0, opg->ops_transfer_pinned == 0));
241 static int osc_page_flush(const struct lu_env *env,
242 const struct cl_page_slice *slice,
245 struct osc_page *opg = cl2osc_page(slice);
248 rc = osc_flush_async_page(env, io, opg);
252 static const struct cl_page_operations osc_page_ops = {
253 .cpo_print = osc_page_print,
254 .cpo_delete = osc_page_delete,
255 .cpo_clip = osc_page_clip,
256 .cpo_cancel = osc_page_cancel,
257 .cpo_flush = osc_page_flush
260 int osc_page_init(const struct lu_env *env, struct cl_object *obj,
261 struct cl_page *page, pgoff_t index)
263 struct osc_object *osc = cl2osc(obj);
264 struct osc_page *opg = cl_object_page_slice(obj, page);
268 opg->ops_to = PAGE_SIZE;
270 result = osc_prep_async_page(osc, opg, page->cp_vmpage,
271 cl_offset(obj, index));
273 struct osc_io *oio = osc_env_io(env);
274 opg->ops_srvlock = osc_io_srvlock(oio);
275 cl_page_slice_add(page, &opg->ops_cl, obj, index,
278 INIT_LIST_HEAD(&opg->ops_lru);
280 /* reserve an LRU space for this page */
281 if (page->cp_type == CPT_CACHEABLE && result == 0) {
282 result = osc_lru_alloc(env, osc_cli(osc), opg);
284 spin_lock(&osc->oo_tree_lock);
285 result = radix_tree_insert(&osc->oo_tree, index, opg);
288 spin_unlock(&osc->oo_tree_lock);
289 LASSERT(result == 0);
297 * Helper function called by osc_io_submit() for every page in an immediate
298 * transfer (i.e., transferred synchronously).
300 void osc_page_submit(const struct lu_env *env, struct osc_page *opg,
301 enum cl_req_type crt, int brw_flags)
303 struct osc_async_page *oap = &opg->ops_oap;
305 LASSERTF(oap->oap_magic == OAP_MAGIC, "Bad oap magic: oap %p, "
306 "magic 0x%x\n", oap, oap->oap_magic);
307 LASSERT(oap->oap_async_flags & ASYNC_READY);
308 LASSERT(oap->oap_async_flags & ASYNC_COUNT_STABLE);
310 oap->oap_cmd = crt == CRT_WRITE ? OBD_BRW_WRITE : OBD_BRW_READ;
311 oap->oap_page_off = opg->ops_from;
312 oap->oap_count = opg->ops_to - opg->ops_from;
313 oap->oap_brw_flags = OBD_BRW_SYNC | brw_flags;
315 if (cfs_capable(CFS_CAP_SYS_RESOURCE)) {
316 oap->oap_brw_flags |= OBD_BRW_NOQUOTA;
317 oap->oap_cmd |= OBD_BRW_NOQUOTA;
320 opg->ops_submit_time = cfs_time_current();
321 osc_page_transfer_get(opg, "transfer\0imm");
322 osc_page_transfer_add(env, opg, crt);
325 /* --------------- LRU page management ------------------ */
327 /* OSC is a natural place to manage LRU pages as applications are specialized
328 * to write OSC by OSC. Ideally, if one OSC is used more frequently it should
329 * occupy more LRU slots. On the other hand, we should avoid using up all LRU
330 * slots (client_obd::cl_lru_left) otherwise process has to be put into sleep
331 * for free LRU slots - this will be very bad so the algorithm requires each
332 * OSC to free slots voluntarily to maintain a reasonable number of free slots
336 static DECLARE_WAIT_QUEUE_HEAD(osc_lru_waitq);
339 * LRU pages are freed in batch mode. OSC should at least free this
340 * number of pages to avoid running out of LRU slots.
342 static inline int lru_shrink_min(struct client_obd *cli)
344 return cli->cl_max_pages_per_rpc * 2;
348 * free this number at most otherwise it will take too long time to finsih.
350 static inline int lru_shrink_max(struct client_obd *cli)
352 return cli->cl_max_pages_per_rpc * cli->cl_max_rpcs_in_flight;
356 * Check if we can free LRU slots from this OSC. If there exists LRU waiters,
357 * we should free slots aggressively. In this way, slots are freed in a steady
358 * step to maintain fairness among OSCs.
360 * Return how many LRU pages should be freed.
362 static int osc_cache_too_much(struct client_obd *cli)
364 struct cl_client_cache *cache = cli->cl_cache;
365 long pages = atomic_long_read(&cli->cl_lru_in_list);
366 unsigned long budget;
368 LASSERT(cache != NULL);
369 budget = cache->ccc_lru_max / (atomic_read(&cache->ccc_users) - 2);
371 /* if it's going to run out LRU slots, we should free some, but not
372 * too much to maintain faireness among OSCs. */
373 if (atomic_long_read(cli->cl_lru_left) < cache->ccc_lru_max >> 2) {
375 return lru_shrink_max(cli);
376 else if (pages >= budget / 2)
377 return lru_shrink_min(cli);
379 int duration = cfs_time_current_sec() - cli->cl_lru_last_used;
381 /* knock out pages by duration of no IO activity */
382 duration >>= 6; /* approximately 1 minute */
383 if (duration > 0 && pages >= budget / duration)
384 return lru_shrink_min(cli);
389 int lru_queue_work(const struct lu_env *env, void *data)
391 struct client_obd *cli = data;
394 CDEBUG(D_CACHE, "%s: run LRU work for client obd\n", cli_name(cli));
395 count = osc_cache_too_much(cli);
397 int rc = osc_lru_shrink(env, cli, count, false);
399 CDEBUG(D_CACHE, "%s: shrank %d/%d pages from client obd\n",
400 cli_name(cli), rc, count);
402 CDEBUG(D_CACHE, "%s: queue again\n", cli_name(cli));
403 ptlrpcd_queue_work(cli->cl_lru_work);
410 void osc_lru_add_batch(struct client_obd *cli, struct list_head *plist)
412 struct list_head lru = LIST_HEAD_INIT(lru);
413 struct osc_async_page *oap;
416 list_for_each_entry(oap, plist, oap_pending_item) {
417 struct osc_page *opg = oap2osc_page(oap);
419 if (!opg->ops_in_lru)
423 LASSERT(list_empty(&opg->ops_lru));
424 list_add(&opg->ops_lru, &lru);
428 spin_lock(&cli->cl_lru_list_lock);
429 list_splice_tail(&lru, &cli->cl_lru_list);
430 atomic_long_sub(npages, &cli->cl_lru_busy);
431 atomic_long_add(npages, &cli->cl_lru_in_list);
432 cli->cl_lru_last_used = cfs_time_current_sec();
433 spin_unlock(&cli->cl_lru_list_lock);
435 if (waitqueue_active(&osc_lru_waitq))
436 (void)ptlrpcd_queue_work(cli->cl_lru_work);
440 static void __osc_lru_del(struct client_obd *cli, struct osc_page *opg)
442 LASSERT(atomic_long_read(&cli->cl_lru_in_list) > 0);
443 list_del_init(&opg->ops_lru);
444 atomic_long_dec(&cli->cl_lru_in_list);
448 * Page is being destroyed. The page may be not in LRU list, if the transfer
449 * has never finished(error occurred).
451 static void osc_lru_del(struct client_obd *cli, struct osc_page *opg)
453 if (opg->ops_in_lru) {
454 spin_lock(&cli->cl_lru_list_lock);
455 if (!list_empty(&opg->ops_lru)) {
456 __osc_lru_del(cli, opg);
458 LASSERT(atomic_long_read(&cli->cl_lru_busy) > 0);
459 atomic_long_dec(&cli->cl_lru_busy);
461 spin_unlock(&cli->cl_lru_list_lock);
463 atomic_long_inc(cli->cl_lru_left);
464 /* this is a great place to release more LRU pages if
465 * this osc occupies too many LRU pages and kernel is
466 * stealing one of them. */
467 if (osc_cache_too_much(cli)) {
468 CDEBUG(D_CACHE, "%s: queue LRU work\n", cli_name(cli));
469 (void)ptlrpcd_queue_work(cli->cl_lru_work);
471 wake_up(&osc_lru_waitq);
473 LASSERT(list_empty(&opg->ops_lru));
478 * Delete page from LRUlist for redirty.
480 static void osc_lru_use(struct client_obd *cli, struct osc_page *opg)
482 /* If page is being transferred for the first time,
483 * ops_lru should be empty */
484 if (opg->ops_in_lru && !list_empty(&opg->ops_lru)) {
485 spin_lock(&cli->cl_lru_list_lock);
486 __osc_lru_del(cli, opg);
487 spin_unlock(&cli->cl_lru_list_lock);
488 atomic_long_inc(&cli->cl_lru_busy);
492 static void discard_pagevec(const struct lu_env *env, struct cl_io *io,
493 struct cl_page **pvec, int max_index)
497 for (i = 0; i < max_index; i++) {
498 struct cl_page *page = pvec[i];
500 LASSERT(cl_page_is_owned(page, io));
501 cl_page_delete(env, page);
502 cl_page_discard(env, io, page);
503 cl_page_disown(env, io, page);
504 cl_page_put(env, page);
511 * Check if a cl_page can be released, i.e, it's not being used.
513 * If unstable account is turned on, bulk transfer may hold one refcount
514 * for recovery so we need to check vmpage refcount as well; otherwise,
515 * even we can destroy cl_page but the corresponding vmpage can't be reused.
517 static inline bool lru_page_busy(struct client_obd *cli, struct cl_page *page)
519 if (cl_page_in_use_noref(page))
522 if (cli->cl_cache->ccc_unstable_check) {
523 struct page *vmpage = cl_page_vmpage(page);
525 /* vmpage have two known users: cl_page and VM page cache */
526 if (page_count(vmpage) - page_mapcount(vmpage) > 2)
533 * Drop @target of pages from LRU at most.
535 long osc_lru_shrink(const struct lu_env *env, struct client_obd *cli,
536 long target, bool force)
539 struct cl_object *clobj = NULL;
540 struct cl_page **pvec;
541 struct osc_page *opg;
548 LASSERT(atomic_long_read(&cli->cl_lru_in_list) >= 0);
549 if (atomic_long_read(&cli->cl_lru_in_list) == 0 || target <= 0)
552 CDEBUG(D_CACHE, "%s: shrinkers: %d, force: %d\n",
553 cli_name(cli), atomic_read(&cli->cl_lru_shrinkers), force);
555 if (atomic_read(&cli->cl_lru_shrinkers) > 0)
558 if (atomic_inc_return(&cli->cl_lru_shrinkers) > 1) {
559 atomic_dec(&cli->cl_lru_shrinkers);
563 atomic_inc(&cli->cl_lru_shrinkers);
566 pvec = (struct cl_page **)osc_env_info(env)->oti_pvec;
567 io = &osc_env_info(env)->oti_io;
569 spin_lock(&cli->cl_lru_list_lock);
571 cli->cl_lru_reclaim++;
572 maxscan = min(target << 1, atomic_long_read(&cli->cl_lru_in_list));
573 while (!list_empty(&cli->cl_lru_list)) {
574 struct cl_page *page;
575 bool will_free = false;
577 if (!force && atomic_read(&cli->cl_lru_shrinkers) > 1)
583 opg = list_entry(cli->cl_lru_list.next, struct osc_page,
585 page = opg->ops_cl.cpl_page;
586 if (lru_page_busy(cli, page)) {
587 list_move_tail(&opg->ops_lru, &cli->cl_lru_list);
591 LASSERT(page->cp_obj != NULL);
592 if (clobj != page->cp_obj) {
593 struct cl_object *tmp = page->cp_obj;
596 spin_unlock(&cli->cl_lru_list_lock);
599 discard_pagevec(env, io, pvec, index);
603 cl_object_put(env, clobj);
609 io->ci_ignore_layout = 1;
610 rc = cl_io_init(env, io, CIT_MISC, clobj);
612 spin_lock(&cli->cl_lru_list_lock);
621 if (cl_page_own_try(env, io, page) == 0) {
622 if (!lru_page_busy(cli, page)) {
623 /* remove it from lru list earlier to avoid
625 __osc_lru_del(cli, opg);
626 opg->ops_in_lru = 0; /* will be discarded */
631 cl_page_disown(env, io, page);
636 list_move_tail(&opg->ops_lru, &cli->cl_lru_list);
640 /* Don't discard and free the page with cl_lru_list held */
641 pvec[index++] = page;
642 if (unlikely(index == OTI_PVEC_SIZE)) {
643 spin_unlock(&cli->cl_lru_list_lock);
644 discard_pagevec(env, io, pvec, index);
647 spin_lock(&cli->cl_lru_list_lock);
650 if (++count >= target)
653 spin_unlock(&cli->cl_lru_list_lock);
656 discard_pagevec(env, io, pvec, index);
659 cl_object_put(env, clobj);
662 atomic_dec(&cli->cl_lru_shrinkers);
664 atomic_long_add(count, cli->cl_lru_left);
665 wake_up_all(&osc_lru_waitq);
667 RETURN(count > 0 ? count : rc);
671 * Reclaim LRU pages by an IO thread. The caller wants to reclaim at least
672 * \@npages of LRU slots. For performance consideration, it's better to drop
673 * LRU pages in batch. Therefore, the actual number is adjusted at least
676 static long osc_lru_reclaim(struct client_obd *cli, unsigned long npages)
679 struct cl_client_cache *cache = cli->cl_cache;
685 LASSERT(cache != NULL);
687 env = cl_env_get(&refcheck);
691 npages = max_t(int, npages, cli->cl_max_pages_per_rpc);
692 CDEBUG(D_CACHE, "%s: start to reclaim %ld pages from LRU\n",
693 cli_name(cli), npages);
694 rc = osc_lru_shrink(env, cli, npages, true);
696 CDEBUG(D_CACHE, "%s: reclaimed %ld/%ld pages from LRU\n",
697 cli_name(cli), rc, npages);
698 if (osc_cache_too_much(cli) > 0)
699 ptlrpcd_queue_work(cli->cl_lru_work);
705 CDEBUG(D_CACHE, "%s: cli %p no free slots, pages: %ld/%ld, want: %ld\n",
706 cli_name(cli), cli, atomic_long_read(&cli->cl_lru_in_list),
707 atomic_long_read(&cli->cl_lru_busy), npages);
709 /* Reclaim LRU slots from other client_obd as it can't free enough
710 * from its own. This should rarely happen. */
711 spin_lock(&cache->ccc_lru_lock);
712 LASSERT(!list_empty(&cache->ccc_lru));
714 cache->ccc_lru_shrinkers++;
715 list_move_tail(&cli->cl_lru_osc, &cache->ccc_lru);
717 max_scans = atomic_read(&cache->ccc_users) - 2;
718 while (--max_scans > 0 && !list_empty(&cache->ccc_lru)) {
719 cli = list_entry(cache->ccc_lru.next, struct client_obd,
722 CDEBUG(D_CACHE, "%s: cli %p LRU pages: %ld, busy: %ld.\n",
724 atomic_long_read(&cli->cl_lru_in_list),
725 atomic_long_read(&cli->cl_lru_busy));
727 list_move_tail(&cli->cl_lru_osc, &cache->ccc_lru);
728 if (osc_cache_too_much(cli) > 0) {
729 spin_unlock(&cache->ccc_lru_lock);
731 rc = osc_lru_shrink(env, cli, npages, true);
732 spin_lock(&cache->ccc_lru_lock);
739 spin_unlock(&cache->ccc_lru_lock);
742 cl_env_put(env, &refcheck);
743 CDEBUG(D_CACHE, "%s: cli %p freed %ld pages.\n",
744 cli_name(cli), cli, rc);
749 * osc_lru_alloc() is called to allocate an LRU slot for a cl_page.
751 * Usually the LRU slots are reserved in osc_io_iter_rw_init().
752 * Only in the case that the LRU slots are in extreme shortage, it should
753 * have reserved enough slots for an IO.
755 static int osc_lru_alloc(const struct lu_env *env, struct client_obd *cli,
756 struct osc_page *opg)
758 struct l_wait_info lwi = LWI_INTR(LWI_ON_SIGNAL_NOOP, NULL);
759 struct osc_io *oio = osc_env_io(env);
763 if (cli->cl_cache == NULL) /* shall not be in LRU */
766 if (oio->oi_lru_reserved > 0) {
767 --oio->oi_lru_reserved;
771 LASSERT(atomic_long_read(cli->cl_lru_left) >= 0);
772 while (!atomic_long_add_unless(cli->cl_lru_left, -1, 0)) {
773 /* run out of LRU spaces, try to drop some by itself */
774 rc = osc_lru_reclaim(cli, 1);
781 rc = l_wait_event(osc_lru_waitq,
782 atomic_long_read(cli->cl_lru_left) > 0,
790 atomic_long_inc(&cli->cl_lru_busy);
799 * osc_lru_reserve() is called to reserve enough LRU slots for I/O.
801 * The benefit of doing this is to reduce contention against atomic counter
802 * cl_lru_left by changing it from per-page access to per-IO access.
804 unsigned long osc_lru_reserve(struct client_obd *cli, unsigned long npages)
806 unsigned long reserved = 0;
807 unsigned long max_pages;
810 /* reserve a full RPC window at most to avoid that a thread accidentally
811 * consumes too many LRU slots */
812 max_pages = cli->cl_max_pages_per_rpc * cli->cl_max_rpcs_in_flight;
813 if (npages > max_pages)
816 c = atomic_long_read(cli->cl_lru_left);
817 if (c < npages && osc_lru_reclaim(cli, npages) > 0)
818 c = atomic_long_read(cli->cl_lru_left);
819 while (c >= npages) {
820 if (c == atomic_long_cmpxchg(cli->cl_lru_left, c, c - npages)) {
824 c = atomic_long_read(cli->cl_lru_left);
826 if (atomic_long_read(cli->cl_lru_left) < max_pages) {
827 /* If there aren't enough pages in the per-OSC LRU then
828 * wake up the LRU thread to try and clear out space, so
829 * we don't block if pages are being dirtied quickly. */
830 CDEBUG(D_CACHE, "%s: queue LRU, left: %lu/%ld.\n",
831 cli_name(cli), atomic_long_read(cli->cl_lru_left),
833 (void)ptlrpcd_queue_work(cli->cl_lru_work);
840 * osc_lru_unreserve() is called to unreserve LRU slots.
842 * LRU slots reserved by osc_lru_reserve() may have entries left due to several
843 * reasons such as page already existing or I/O error. Those reserved slots
844 * should be freed by calling this function.
846 void osc_lru_unreserve(struct client_obd *cli, unsigned long npages)
848 atomic_long_add(npages, cli->cl_lru_left);
849 wake_up_all(&osc_lru_waitq);
853 * Atomic operations are expensive. We accumulate the accounting for the
854 * same page zone to get better performance.
855 * In practice this can work pretty good because the pages in the same RPC
856 * are likely from the same page zone.
858 static inline void unstable_page_accounting(struct ptlrpc_bulk_desc *desc,
861 int page_count = desc->bd_iov_count;
866 LASSERT(ptlrpc_is_bulk_desc_kiov(desc->bd_type));
868 for (i = 0; i < page_count; i++) {
869 void *pz = page_zone(BD_GET_KIOV(desc, i).kiov_page);
871 if (likely(pz == zone)) {
877 mod_zone_page_state(zone, NR_UNSTABLE_NFS,
885 mod_zone_page_state(zone, NR_UNSTABLE_NFS, factor * count);
888 static inline void add_unstable_page_accounting(struct ptlrpc_bulk_desc *desc)
890 unstable_page_accounting(desc, 1);
893 static inline void dec_unstable_page_accounting(struct ptlrpc_bulk_desc *desc)
895 unstable_page_accounting(desc, -1);
899 * Performs "unstable" page accounting. This function balances the
900 * increment operations performed in osc_inc_unstable_pages. It is
901 * registered as the RPC request callback, and is executed when the
902 * bulk RPC is committed on the server. Thus at this point, the pages
903 * involved in the bulk transfer are no longer considered unstable.
905 * If this function is called, the request should have been committed
906 * or req:rq_unstable must have been set; it implies that the unstable
907 * statistic have been added.
909 void osc_dec_unstable_pages(struct ptlrpc_request *req)
911 struct ptlrpc_bulk_desc *desc = req->rq_bulk;
912 struct client_obd *cli = &req->rq_import->imp_obd->u.cli;
913 int page_count = desc->bd_iov_count;
916 LASSERT(page_count >= 0);
917 dec_unstable_page_accounting(desc);
919 unstable_count = atomic_long_sub_return(page_count,
920 &cli->cl_unstable_count);
921 LASSERT(unstable_count >= 0);
923 unstable_count = atomic_long_sub_return(page_count,
924 &cli->cl_cache->ccc_unstable_nr);
925 LASSERT(unstable_count >= 0);
926 if (unstable_count == 0)
927 wake_up_all(&cli->cl_cache->ccc_unstable_waitq);
929 if (waitqueue_active(&osc_lru_waitq))
930 (void)ptlrpcd_queue_work(cli->cl_lru_work);
934 * "unstable" page accounting. See: osc_dec_unstable_pages.
936 void osc_inc_unstable_pages(struct ptlrpc_request *req)
938 struct ptlrpc_bulk_desc *desc = req->rq_bulk;
939 struct client_obd *cli = &req->rq_import->imp_obd->u.cli;
940 long page_count = desc->bd_iov_count;
942 /* No unstable page tracking */
943 if (cli->cl_cache == NULL || !cli->cl_cache->ccc_unstable_check)
946 add_unstable_page_accounting(desc);
947 atomic_long_add(page_count, &cli->cl_unstable_count);
948 atomic_long_add(page_count, &cli->cl_cache->ccc_unstable_nr);
950 /* If the request has already been committed (i.e. brw_commit
951 * called via rq_commit_cb), we need to undo the unstable page
952 * increments we just performed because rq_commit_cb wont be
954 spin_lock(&req->rq_lock);
955 if (unlikely(req->rq_committed)) {
956 spin_unlock(&req->rq_lock);
958 osc_dec_unstable_pages(req);
960 req->rq_unstable = 1;
961 spin_unlock(&req->rq_lock);
966 * Check if it piggybacks SOFT_SYNC flag to OST from this OSC.
967 * This function will be called by every BRW RPC so it's critical
968 * to make this function fast.
970 bool osc_over_unstable_soft_limit(struct client_obd *cli)
972 long unstable_nr, osc_unstable_count;
974 /* Can't check cli->cl_unstable_count, therefore, no soft limit */
975 if (cli->cl_cache == NULL || !cli->cl_cache->ccc_unstable_check)
978 osc_unstable_count = atomic_long_read(&cli->cl_unstable_count);
979 unstable_nr = atomic_long_read(&cli->cl_cache->ccc_unstable_nr);
982 "%s: cli: %p unstable pages: %lu, osc unstable pages: %lu\n",
983 cli_name(cli), cli, unstable_nr, osc_unstable_count);
985 /* If the LRU slots are in shortage - 25% remaining AND this OSC
986 * has one full RPC window of unstable pages, it's a good chance
987 * to piggyback a SOFT_SYNC flag.
988 * Please notice that the OST won't take immediate response for the
989 * SOFT_SYNC request so active OSCs will have more chance to carry
990 * the flag, this is reasonable. */
991 return unstable_nr > cli->cl_cache->ccc_lru_max >> 2 &&
992 osc_unstable_count > cli->cl_max_pages_per_rpc *
993 cli->cl_max_rpcs_in_flight;
997 * Return how many LRU pages in the cache of all OSC devices
999 * \retval return # of cached LRU pages times reclaimation tendency
1000 * \retval SHRINK_STOP if it cannot do any scanning in this time
1002 unsigned long osc_cache_shrink_count(struct shrinker *sk,
1003 struct shrink_control *sc)
1005 struct client_obd *cli;
1006 unsigned long cached = 0;
1008 spin_lock(&osc_shrink_lock);
1009 list_for_each_entry(cli, &osc_shrink_list, cl_shrink_list)
1010 cached += atomic_long_read(&cli->cl_lru_in_list);
1011 spin_unlock(&osc_shrink_lock);
1013 return (cached * sysctl_vfs_cache_pressure) / 100;
1017 * Scan and try to reclaim sc->nr_to_scan cached LRU pages
1019 * \retval number of cached LRU pages reclaimed
1020 * \retval SHRINK_STOP if it cannot do any scanning in this time
1022 * Linux kernel will loop calling this shrinker scan routine with
1023 * sc->nr_to_scan = SHRINK_BATCH(128 for now) until kernel got enough memory.
1025 * If sc->nr_to_scan is 0, the VM is querying the cache size, we don't need
1026 * to scan and try to reclaim LRU pages, just return 0 and
1027 * osc_cache_shrink_count() will report the LRU page number.
1029 unsigned long osc_cache_shrink_scan(struct shrinker *sk,
1030 struct shrink_control *sc)
1032 struct client_obd *cli;
1033 struct client_obd *stop_anchor = NULL;
1039 if (sc->nr_to_scan == 0)
1042 if (!(sc->gfp_mask & __GFP_FS))
1045 env = cl_env_get(&refcheck);
1049 spin_lock(&osc_shrink_lock);
1050 while (!list_empty(&osc_shrink_list)) {
1051 cli = list_entry(osc_shrink_list.next, struct client_obd,
1054 if (stop_anchor == NULL)
1056 else if (cli == stop_anchor)
1059 list_move_tail(&cli->cl_shrink_list, &osc_shrink_list);
1060 spin_unlock(&osc_shrink_lock);
1062 /* shrink no more than max_pages_per_rpc for an OSC */
1063 rc = osc_lru_shrink(env, cli, (sc->nr_to_scan - shrank) >
1064 cli->cl_max_pages_per_rpc ?
1065 cli->cl_max_pages_per_rpc :
1066 sc->nr_to_scan - shrank, true);
1070 if (shrank >= sc->nr_to_scan)
1073 spin_lock(&osc_shrink_lock);
1075 spin_unlock(&osc_shrink_lock);
1078 cl_env_put(env, &refcheck);