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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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21 * CA 95054 USA or visit www.sun.com if you need additional information or
27 * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
28 * Use is subject to license terms.
30 * Copyright (c) 2011, 2012, Intel Corporation.
33 * This file is part of Lustre, http://www.lustre.org/
34 * Lustre is a trademark of Sun Microsystems, Inc.
36 * lustre/ptlrpc/ptlrpcd.c
39 /** \defgroup ptlrpcd PortalRPC daemon
41 * ptlrpcd is a special thread with its own set where other user might add
42 * requests when they don't want to wait for their completion.
43 * PtlRPCD will take care of sending such requests and then processing their
44 * replies and calling completion callbacks as necessary.
45 * The callbacks are called directly from ptlrpcd context.
46 * It is important to never significantly block (esp. on RPCs!) within such
47 * completion handler or a deadlock might occur where ptlrpcd enters some
48 * callback that attempts to send another RPC and wait for it to return,
49 * during which time ptlrpcd is completely blocked, so e.g. if import
50 * fails, recovery cannot progress because connection requests are also
56 #define DEBUG_SUBSYSTEM S_RPC
58 #include "../../include/linux/libcfs/libcfs.h"
60 #include "../include/lustre_net.h"
61 #include "../include/lustre_lib.h"
62 #include "../include/lustre_ha.h"
63 #include "../include/obd_class.h" /* for obd_zombie */
64 #include "../include/obd_support.h" /* for OBD_FAIL_CHECK */
65 #include "../include/cl_object.h" /* cl_env_{get,put}() */
66 #include "../include/lprocfs_status.h"
68 #include "ptlrpc_internal.h"
70 /* One of these per CPT. */
78 struct ptlrpcd_ctl pd_threads[0];
82 * max_ptlrpcds is obsolete, but retained to ensure that the kernel
83 * module will load on a system where it has been tuned.
84 * A value other than 0 implies it was tuned, in which case the value
85 * is used to derive a setting for ptlrpcd_per_cpt_max.
87 static int max_ptlrpcds;
88 module_param(max_ptlrpcds, int, 0644);
89 MODULE_PARM_DESC(max_ptlrpcds, "Max ptlrpcd thread count to be started.");
92 * ptlrpcd_bind_policy is obsolete, but retained to ensure that
93 * the kernel module will load on a system where it has been tuned.
94 * A value other than 0 implies it was tuned, in which case the value
95 * is used to derive a setting for ptlrpcd_partner_group_size.
97 static int ptlrpcd_bind_policy;
98 module_param(ptlrpcd_bind_policy, int, 0644);
99 MODULE_PARM_DESC(ptlrpcd_bind_policy,
100 "Ptlrpcd threads binding mode (obsolete).");
103 * ptlrpcd_per_cpt_max: The maximum number of ptlrpcd threads to run
106 static int ptlrpcd_per_cpt_max;
107 module_param(ptlrpcd_per_cpt_max, int, 0644);
108 MODULE_PARM_DESC(ptlrpcd_per_cpt_max,
109 "Max ptlrpcd thread count to be started per cpt.");
112 * ptlrpcd_partner_group_size: The desired number of threads in each
113 * ptlrpcd partner thread group. Default is 2, corresponding to the
114 * old PDB_POLICY_PAIR. A negative value makes all ptlrpcd threads in
115 * a CPT partners of each other.
117 static int ptlrpcd_partner_group_size;
118 module_param(ptlrpcd_partner_group_size, int, 0644);
119 MODULE_PARM_DESC(ptlrpcd_partner_group_size,
120 "Number of ptlrpcd threads in a partner group.");
123 * ptlrpcd_cpts: A CPT string describing the CPU partitions that
124 * ptlrpcd threads should run on. Used to make ptlrpcd threads run on
125 * a subset of all CPTs.
129 * run ptlrpcd threads only on CPT 2.
133 * run ptlrpcd threads on CPTs 0, 1, 2, and 3.
135 * ptlrpcd_cpts=[0-3,5,7]
136 * run ptlrpcd threads on CPTS 0, 1, 2, 3, 5, and 7.
138 static char *ptlrpcd_cpts;
139 module_param(ptlrpcd_cpts, charp, 0644);
140 MODULE_PARM_DESC(ptlrpcd_cpts,
141 "CPU partitions ptlrpcd threads should run in");
143 /* ptlrpcds_cpt_idx maps cpt numbers to an index in the ptlrpcds array. */
144 static int *ptlrpcds_cpt_idx;
146 /* ptlrpcds_num is the number of entries in the ptlrpcds array. */
147 static int ptlrpcds_num;
148 static struct ptlrpcd **ptlrpcds;
151 * In addition to the regular thread pool above, there is a single
152 * global recovery thread. Recovery isn't critical for performance,
153 * and doesn't block, but must always be able to proceed, and it is
154 * possible that all normal ptlrpcd threads are blocked. Hence the
155 * need for a dedicated thread.
157 static struct ptlrpcd_ctl ptlrpcd_rcv;
159 struct mutex ptlrpcd_mutex;
160 static int ptlrpcd_users;
162 void ptlrpcd_wake(struct ptlrpc_request *req)
164 struct ptlrpc_request_set *rq_set = req->rq_set;
166 LASSERT(rq_set != NULL);
168 wake_up(&rq_set->set_waitq);
170 EXPORT_SYMBOL(ptlrpcd_wake);
172 static struct ptlrpcd_ctl *
173 ptlrpcd_select_pc(struct ptlrpc_request *req)
179 if (req != NULL && req->rq_send_state != LUSTRE_IMP_FULL)
182 cpt = cfs_cpt_current(cfs_cpt_table, 1);
183 if (!ptlrpcds_cpt_idx)
186 idx = ptlrpcds_cpt_idx[cpt];
189 /* We do not care whether it is strict load balance. */
191 if (++idx == pd->pd_nthreads)
195 return &pd->pd_threads[idx];
199 * Return transferred RPCs count.
201 static int ptlrpcd_steal_rqset(struct ptlrpc_request_set *des,
202 struct ptlrpc_request_set *src)
204 struct list_head *tmp, *pos;
205 struct ptlrpc_request *req;
208 spin_lock(&src->set_new_req_lock);
209 if (likely(!list_empty(&src->set_new_requests))) {
210 list_for_each_safe(pos, tmp, &src->set_new_requests) {
211 req = list_entry(pos, struct ptlrpc_request,
215 list_splice_init(&src->set_new_requests,
217 rc = atomic_read(&src->set_new_count);
218 atomic_add(rc, &des->set_remaining);
219 atomic_set(&src->set_new_count, 0);
221 spin_unlock(&src->set_new_req_lock);
226 * Requests that are added to the ptlrpcd queue are sent via
227 * ptlrpcd_check->ptlrpc_check_set().
229 void ptlrpcd_add_req(struct ptlrpc_request *req)
231 struct ptlrpcd_ctl *pc;
234 lustre_msg_set_jobid(req->rq_reqmsg, NULL);
236 spin_lock(&req->rq_lock);
237 if (req->rq_invalid_rqset) {
238 struct l_wait_info lwi = LWI_TIMEOUT(cfs_time_seconds(5),
239 back_to_sleep, NULL);
241 req->rq_invalid_rqset = 0;
242 spin_unlock(&req->rq_lock);
243 l_wait_event(req->rq_set_waitq, (req->rq_set == NULL), &lwi);
244 } else if (req->rq_set) {
245 /* If we have a valid "rq_set", just reuse it to avoid double
247 LASSERT(req->rq_phase == RQ_PHASE_NEW);
248 LASSERT(req->rq_send_state == LUSTRE_IMP_REPLAY);
250 /* ptlrpc_check_set will decrease the count */
251 atomic_inc(&req->rq_set->set_remaining);
252 spin_unlock(&req->rq_lock);
253 wake_up(&req->rq_set->set_waitq);
256 spin_unlock(&req->rq_lock);
259 pc = ptlrpcd_select_pc(req);
261 DEBUG_REQ(D_INFO, req, "add req [%p] to pc [%s:%d]",
262 req, pc->pc_name, pc->pc_index);
264 ptlrpc_set_add_new_req(pc, req);
266 EXPORT_SYMBOL(ptlrpcd_add_req);
268 static inline void ptlrpc_reqset_get(struct ptlrpc_request_set *set)
270 atomic_inc(&set->set_refcount);
274 * Check if there is more work to do on ptlrpcd set.
277 static int ptlrpcd_check(struct lu_env *env, struct ptlrpcd_ctl *pc)
279 struct list_head *tmp, *pos;
280 struct ptlrpc_request *req;
281 struct ptlrpc_request_set *set = pc->pc_set;
285 if (atomic_read(&set->set_new_count)) {
286 spin_lock(&set->set_new_req_lock);
287 if (likely(!list_empty(&set->set_new_requests))) {
288 list_splice_init(&set->set_new_requests,
290 atomic_add(atomic_read(&set->set_new_count),
291 &set->set_remaining);
292 atomic_set(&set->set_new_count, 0);
294 * Need to calculate its timeout.
298 spin_unlock(&set->set_new_req_lock);
301 /* We should call lu_env_refill() before handling new requests to make
302 * sure that env key the requests depending on really exists.
304 rc2 = lu_env_refill(env);
307 * XXX This is very awkward situation, because
308 * execution can neither continue (request
309 * interpreters assume that env is set up), nor repeat
310 * the loop (as this potentially results in a tight
311 * loop of -ENOMEM's).
313 * Fortunately, refill only ever does something when
314 * new modules are loaded, i.e., early during boot up.
316 CERROR("Failure to refill session: %d\n", rc2);
320 if (atomic_read(&set->set_remaining))
321 rc |= ptlrpc_check_set(env, set);
323 /* NB: ptlrpc_check_set has already moved completed request at the
324 * head of seq::set_requests */
325 list_for_each_safe(pos, tmp, &set->set_requests) {
326 req = list_entry(pos, struct ptlrpc_request, rq_set_chain);
327 if (req->rq_phase != RQ_PHASE_COMPLETE)
330 list_del_init(&req->rq_set_chain);
332 ptlrpc_req_finished(req);
337 * If new requests have been added, make sure to wake up.
339 rc = atomic_read(&set->set_new_count);
341 /* If we have nothing to do, check whether we can take some
342 * work from our partner threads. */
343 if (rc == 0 && pc->pc_npartners > 0) {
344 struct ptlrpcd_ctl *partner;
345 struct ptlrpc_request_set *ps;
346 int first = pc->pc_cursor;
349 partner = pc->pc_partners[pc->pc_cursor++];
350 if (pc->pc_cursor >= pc->pc_npartners)
355 spin_lock(&partner->pc_lock);
356 ps = partner->pc_set;
358 spin_unlock(&partner->pc_lock);
362 ptlrpc_reqset_get(ps);
363 spin_unlock(&partner->pc_lock);
365 if (atomic_read(&ps->set_new_count)) {
366 rc = ptlrpcd_steal_rqset(set, ps);
368 CDEBUG(D_RPCTRACE, "transfer %d async RPCs [%d->%d]\n",
369 rc, partner->pc_index,
372 ptlrpc_reqset_put(ps);
373 } while (rc == 0 && pc->pc_cursor != first);
381 * Main ptlrpcd thread.
382 * ptlrpc's code paths like to execute in process context, so we have this
383 * thread which spins on a set which contains the rpcs and sends them.
386 static int ptlrpcd(void *arg)
388 struct ptlrpcd_ctl *pc = arg;
389 struct ptlrpc_request_set *set;
390 struct lu_env env = { .le_ses = NULL };
395 if (cfs_cpt_bind(cfs_cpt_table, pc->pc_cpt) != 0)
396 CWARN("Failed to bind %s on CPT %d\n", pc->pc_name, pc->pc_cpt);
399 * Allocate the request set after the thread has been bound
400 * above. This is safe because no requests will be queued
401 * until all ptlrpcd threads have confirmed that they have
402 * successfully started.
404 set = ptlrpc_prep_set();
409 spin_lock(&pc->pc_lock);
411 spin_unlock(&pc->pc_lock);
413 * XXX So far only "client" ptlrpcd uses an environment. In
414 * the future, ptlrpcd thread (or a thread-set) has to given
415 * an argument, describing its "scope".
417 rc = lu_context_init(&env.le_ctx,
418 LCT_CL_THREAD|LCT_REMEMBER|LCT_NOREF);
422 complete(&pc->pc_starting);
426 * This mainloop strongly resembles ptlrpc_set_wait() except that our
427 * set never completes. ptlrpcd_check() calls ptlrpc_check_set() when
428 * there are requests in the set. New requests come in on the set's
429 * new_req_list and ptlrpcd_check() moves them into the set.
432 struct l_wait_info lwi;
435 timeout = ptlrpc_set_next_timeout(set);
436 lwi = LWI_TIMEOUT(cfs_time_seconds(timeout ? timeout : 1),
437 ptlrpc_expired_set, set);
439 lu_context_enter(&env.le_ctx);
440 l_wait_event(set->set_waitq,
441 ptlrpcd_check(&env, pc), &lwi);
442 lu_context_exit(&env.le_ctx);
445 * Abort inflight rpcs for forced stop case.
447 if (test_bit(LIOD_STOP, &pc->pc_flags)) {
448 if (test_bit(LIOD_FORCE, &pc->pc_flags))
449 ptlrpc_abort_set(set);
454 * Let's make one more loop to make sure that ptlrpcd_check()
455 * copied all raced new rpcs into the set so we can kill them.
460 * Wait for inflight requests to drain.
462 if (!list_empty(&set->set_requests))
463 ptlrpc_set_wait(set);
464 lu_context_fini(&env.le_ctx);
466 complete(&pc->pc_finishing);
471 complete(&pc->pc_starting);
475 static void ptlrpcd_ctl_init(struct ptlrpcd_ctl *pc, int index, int cpt)
477 pc->pc_index = index;
479 init_completion(&pc->pc_starting);
480 init_completion(&pc->pc_finishing);
481 spin_lock_init(&pc->pc_lock);
484 /* Recovery thread. */
485 snprintf(pc->pc_name, sizeof(pc->pc_name), "ptlrpcd_rcv");
487 /* Regular thread. */
488 snprintf(pc->pc_name, sizeof(pc->pc_name),
489 "ptlrpcd_%02d_%02d", cpt, index);
493 /* XXX: We want multiple CPU cores to share the async RPC load. So we
494 * start many ptlrpcd threads. We also want to reduce the ptlrpcd
495 * overhead caused by data transfer cross-CPU cores. So we bind
496 * all ptlrpcd threads to a CPT, in the expectation that CPTs
497 * will be defined in a way that matches these boundaries. Within
498 * a CPT a ptlrpcd thread can be scheduled on any available core.
500 * Each ptlrpcd thread has its own request queue. This can cause
501 * response delay if the thread is already busy. To help with
502 * this we define partner threads: these are other threads bound
503 * to the same CPT which will check for work in each other's
504 * request queues if they have no work to do.
506 * The desired number of partner threads can be tuned by setting
507 * ptlrpcd_partner_group_size. The default is to create pairs of
510 static int ptlrpcd_partners(struct ptlrpcd *pd, int index)
512 struct ptlrpcd_ctl *pc;
513 struct ptlrpcd_ctl **ppc;
519 LASSERT(index >= 0 && index < pd->pd_nthreads);
520 pc = &pd->pd_threads[index];
521 pc->pc_npartners = pd->pd_groupsize - 1;
523 if (pc->pc_npartners <= 0)
526 size = sizeof(struct ptlrpcd_ctl *) * pc->pc_npartners;
527 pc->pc_partners = kzalloc_node(size, GFP_NOFS,
528 cfs_cpt_spread_node(cfs_cpt_table,
530 if (!pc->pc_partners) {
531 pc->pc_npartners = 0;
536 first = index - index % pd->pd_groupsize;
537 ppc = pc->pc_partners;
538 for (i = first; i < first + pd->pd_groupsize; i++) {
540 *ppc++ = &pd->pd_threads[i];
546 int ptlrpcd_start(struct ptlrpcd_ctl *pc)
548 struct task_struct *task;
552 * Do not allow start second thread for one pc.
554 if (test_and_set_bit(LIOD_START, &pc->pc_flags)) {
555 CWARN("Starting second thread (%s) for same pc %p\n",
561 * So far only "client" ptlrpcd uses an environment. In the future,
562 * ptlrpcd thread (or a thread-set) has to be given an argument,
563 * describing its "scope".
565 rc = lu_context_init(&pc->pc_env.le_ctx, LCT_CL_THREAD|LCT_REMEMBER);
569 task = kthread_run(ptlrpcd, pc, "%s", pc->pc_name);
575 wait_for_completion(&pc->pc_starting);
583 if (pc->pc_set != NULL) {
584 struct ptlrpc_request_set *set = pc->pc_set;
586 spin_lock(&pc->pc_lock);
588 spin_unlock(&pc->pc_lock);
589 ptlrpc_set_destroy(set);
591 lu_context_fini(&pc->pc_env.le_ctx);
594 clear_bit(LIOD_START, &pc->pc_flags);
598 void ptlrpcd_stop(struct ptlrpcd_ctl *pc, int force)
600 if (!test_bit(LIOD_START, &pc->pc_flags)) {
601 CWARN("Thread for pc %p was not started\n", pc);
605 set_bit(LIOD_STOP, &pc->pc_flags);
607 set_bit(LIOD_FORCE, &pc->pc_flags);
608 wake_up(&pc->pc_set->set_waitq);
611 void ptlrpcd_free(struct ptlrpcd_ctl *pc)
613 struct ptlrpc_request_set *set = pc->pc_set;
615 if (!test_bit(LIOD_START, &pc->pc_flags)) {
616 CWARN("Thread for pc %p was not started\n", pc);
620 wait_for_completion(&pc->pc_finishing);
621 lu_context_fini(&pc->pc_env.le_ctx);
623 spin_lock(&pc->pc_lock);
625 spin_unlock(&pc->pc_lock);
626 ptlrpc_set_destroy(set);
628 clear_bit(LIOD_START, &pc->pc_flags);
629 clear_bit(LIOD_STOP, &pc->pc_flags);
630 clear_bit(LIOD_FORCE, &pc->pc_flags);
633 if (pc->pc_npartners > 0) {
634 LASSERT(pc->pc_partners != NULL);
636 kfree(pc->pc_partners);
637 pc->pc_partners = NULL;
639 pc->pc_npartners = 0;
643 static void ptlrpcd_fini(void)
648 if (ptlrpcds != NULL) {
649 for (i = 0; i < ptlrpcds_num; i++) {
652 for (j = 0; j < ptlrpcds[i]->pd_nthreads; j++)
653 ptlrpcd_stop(&ptlrpcds[i]->pd_threads[j], 0);
654 for (j = 0; j < ptlrpcds[i]->pd_nthreads; j++)
655 ptlrpcd_free(&ptlrpcds[i]->pd_threads[j]);
663 ptlrpcd_stop(&ptlrpcd_rcv, 0);
664 ptlrpcd_free(&ptlrpcd_rcv);
666 kfree(ptlrpcds_cpt_idx);
667 ptlrpcds_cpt_idx = NULL;
670 static int ptlrpcd_init(void)
678 struct cfs_cpt_table *cptable;
685 * Determine the CPTs that ptlrpcd threads will run on.
687 cptable = cfs_cpt_table;
688 ncpts = cfs_cpt_number(cptable);
690 struct cfs_expr_list *el;
692 size = ncpts * sizeof(ptlrpcds_cpt_idx[0]);
693 ptlrpcds_cpt_idx = kzalloc(size, GFP_KERNEL);
694 if (!ptlrpcds_cpt_idx) {
699 rc = cfs_expr_list_parse(ptlrpcd_cpts,
700 strlen(ptlrpcd_cpts),
704 CERROR("ptlrpcd_cpts: invalid CPT pattern string: %s",
710 rc = cfs_expr_list_values(el, ncpts, &cpts);
711 cfs_expr_list_free(el);
713 CERROR("ptlrpcd_cpts: failed to parse CPT array %s: %d\n",
721 * Create the cpt-to-index map. When there is no match
722 * in the cpt table, pick a cpt at random. This could
723 * be changed to take the topology of the system into
726 for (cpt = 0; cpt < ncpts; cpt++) {
727 for (i = 0; i < rc; i++)
732 ptlrpcds_cpt_idx[cpt] = i;
735 cfs_expr_list_values_free(cpts, rc);
738 ptlrpcds_num = ncpts;
740 size = ncpts * sizeof(ptlrpcds[0]);
741 ptlrpcds = kzalloc(size, GFP_KERNEL);
748 * The max_ptlrpcds parameter is obsolete, but do something
749 * sane if it has been tuned, and complain if
750 * ptlrpcd_per_cpt_max has also been tuned.
752 if (max_ptlrpcds != 0) {
753 CWARN("max_ptlrpcds is obsolete.\n");
754 if (ptlrpcd_per_cpt_max == 0) {
755 ptlrpcd_per_cpt_max = max_ptlrpcds / ncpts;
756 /* Round up if there is a remainder. */
757 if (max_ptlrpcds % ncpts != 0)
758 ptlrpcd_per_cpt_max++;
759 CWARN("Setting ptlrpcd_per_cpt_max = %d\n",
760 ptlrpcd_per_cpt_max);
762 CWARN("ptlrpd_per_cpt_max is also set!\n");
767 * The ptlrpcd_bind_policy parameter is obsolete, but do
768 * something sane if it has been tuned, and complain if
769 * ptlrpcd_partner_group_size is also tuned.
771 if (ptlrpcd_bind_policy != 0) {
772 CWARN("ptlrpcd_bind_policy is obsolete.\n");
773 if (ptlrpcd_partner_group_size == 0) {
774 switch (ptlrpcd_bind_policy) {
775 case 1: /* PDB_POLICY_NONE */
776 case 2: /* PDB_POLICY_FULL */
777 ptlrpcd_partner_group_size = 1;
779 case 3: /* PDB_POLICY_PAIR */
780 ptlrpcd_partner_group_size = 2;
782 case 4: /* PDB_POLICY_NEIGHBOR */
784 ptlrpcd_partner_group_size = -1; /* CPT */
786 ptlrpcd_partner_group_size = 3; /* Triplets */
789 default: /* Illegal value, use the default. */
790 ptlrpcd_partner_group_size = 2;
793 CWARN("Setting ptlrpcd_partner_group_size = %d\n",
794 ptlrpcd_partner_group_size);
796 CWARN("ptlrpcd_partner_group_size is also set!\n");
800 if (ptlrpcd_partner_group_size == 0)
801 ptlrpcd_partner_group_size = 2;
802 else if (ptlrpcd_partner_group_size < 0)
803 ptlrpcd_partner_group_size = -1;
804 else if (ptlrpcd_per_cpt_max > 0 &&
805 ptlrpcd_partner_group_size > ptlrpcd_per_cpt_max)
806 ptlrpcd_partner_group_size = ptlrpcd_per_cpt_max;
809 * Start the recovery thread first.
811 set_bit(LIOD_RECOVERY, &ptlrpcd_rcv.pc_flags);
812 ptlrpcd_ctl_init(&ptlrpcd_rcv, -1, CFS_CPT_ANY);
813 rc = ptlrpcd_start(&ptlrpcd_rcv);
817 for (i = 0; i < ncpts; i++) {
823 nthreads = cfs_cpt_weight(cptable, cpt);
824 if (ptlrpcd_per_cpt_max > 0 && ptlrpcd_per_cpt_max < nthreads)
825 nthreads = ptlrpcd_per_cpt_max;
829 if (ptlrpcd_partner_group_size <= 0) {
830 groupsize = nthreads;
831 } else if (nthreads <= ptlrpcd_partner_group_size) {
832 groupsize = nthreads;
834 groupsize = ptlrpcd_partner_group_size;
835 if (nthreads % groupsize != 0)
836 nthreads += groupsize - (nthreads % groupsize);
839 size = offsetof(struct ptlrpcd, pd_threads[nthreads]);
840 pd = kzalloc_node(size, GFP_NOFS,
841 cfs_cpt_spread_node(cfs_cpt_table, cpt));
850 pd->pd_nthreads = nthreads;
851 pd->pd_groupsize = groupsize;
855 * The ptlrpcd threads in a partner group can access
856 * each other's struct ptlrpcd_ctl, so these must be
857 * initialized before any thread is started.
859 for (j = 0; j < nthreads; j++) {
860 ptlrpcd_ctl_init(&pd->pd_threads[j], j, cpt);
861 rc = ptlrpcd_partners(pd, j);
866 /* XXX: We start nthreads ptlrpc daemons.
867 * Each of them can process any non-recovery
868 * async RPC to improve overall async RPC
871 * But there are some issues with async I/O RPCs
872 * and async non-I/O RPCs processed in the same
873 * set under some cases. The ptlrpcd may be
874 * blocked by some async I/O RPC(s), then will
875 * cause other async non-I/O RPC(s) can not be
878 * Maybe we should distinguish blocked async RPCs
879 * from non-blocked async RPCs, and process them
880 * in different ptlrpcd sets to avoid unnecessary
881 * dependency. But how to distribute async RPCs
882 * load among all the ptlrpc daemons becomes
885 for (j = 0; j < nthreads; j++) {
886 rc = ptlrpcd_start(&pd->pd_threads[j]);
898 int ptlrpcd_addref(void)
902 mutex_lock(&ptlrpcd_mutex);
903 if (++ptlrpcd_users == 1)
905 mutex_unlock(&ptlrpcd_mutex);
908 EXPORT_SYMBOL(ptlrpcd_addref);
910 void ptlrpcd_decref(void)
912 mutex_lock(&ptlrpcd_mutex);
913 if (--ptlrpcd_users == 0)
915 mutex_unlock(&ptlrpcd_mutex);
917 EXPORT_SYMBOL(ptlrpcd_decref);