zfs/lib/libumem/umem_update_thread.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21
  22 /*
  23  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
  24  * Use is subject to license terms.
  25  */
  26
  27 #pragma ident   "%Z%%M% %I%     %E% SMI"
  28
  29 #include "umem_base.h"
  30 #include "vmem_base.h"
  31
  32 #include <signal.h>
  33
  34 /*ARGSUSED*/
  35 static void *
  36 umem_update_thread(void *arg)
  37 {
  38         struct timeval now;
  39         int in_update = 0;
  40
  41         (void) mutex_lock(&umem_update_lock);
  42
  43         ASSERT(umem_update_thr == thr_self());
  44         ASSERT(umem_st_update_thr == 0);
  45
  46         for (;;) {
  47                 umem_process_updates();
  48
  49                 if (in_update) {
  50                         in_update = 0;
  51                         /*
  52                          * we wait until now to set the next update time
  53                          * so that the updates are self-throttling
  54                          */
  55                         (void) gettimeofday(&umem_update_next, NULL);
  56                         umem_update_next.tv_sec += umem_reap_interval;
  57                 }
  58
  59                 switch (umem_reaping) {
  60                 case UMEM_REAP_DONE:
  61                 case UMEM_REAP_ADDING:
  62                         break;
  63
  64                 case UMEM_REAP_ACTIVE:
  65                         umem_reap_next = gethrtime() +
  66                             (hrtime_t)umem_reap_interval * NANOSEC;
  67                         umem_reaping = UMEM_REAP_DONE;
  68                         break;
  69
  70                 default:
  71                         ASSERT(umem_reaping == UMEM_REAP_DONE ||
  72                             umem_reaping == UMEM_REAP_ADDING ||
  73                             umem_reaping == UMEM_REAP_ACTIVE);
  74                         break;
  75                 }
  76
  77                 (void) gettimeofday(&now, NULL);
  78                 if (now.tv_sec > umem_update_next.tv_sec ||
  79                     (now.tv_sec == umem_update_next.tv_sec &&
  80                     now.tv_usec >= umem_update_next.tv_usec)) {
  81                         /*
  82                          * Time to run an update
  83                          */
  84                         (void) mutex_unlock(&umem_update_lock);
  85
  86                         vmem_update(NULL);
  87                         /*
  88                          * umem_cache_update can use umem_add_update to
  89                          * request further work.  The update is not complete
  90                          * until all such work is finished.
  91                          */
  92                         umem_cache_applyall(umem_cache_update);
  93
  94                         (void) mutex_lock(&umem_update_lock);
  95                         in_update = 1;
  96                         continue;       /* start processing immediately */
  97                 }
  98
  99                 /*
 100                  * if there is no work to do, we wait until it is time for
 101                  * next update, or someone wakes us.
 102                  */
 103                 if (umem_null_cache.cache_unext == &umem_null_cache) {
 104                         int cancel_state;
 105                         timespec_t abs_time;
 106                         abs_time.tv_sec = umem_update_next.tv_sec;
 107                         abs_time.tv_nsec = umem_update_next.tv_usec * 1000;
 108
 109                         (void) pthread_setcancelstate(PTHREAD_CANCEL_DISABLE,
 110                             &cancel_state);
 111                         (void) cond_timedwait(&umem_update_cv,
 112                             &umem_update_lock, &abs_time);
 113                         (void) pthread_setcancelstate(cancel_state, NULL);
 114                 }
 115         }
 116         /* LINTED no return statement */
 117 }
 118
 119 int
 120 umem_create_update_thread(void)
 121 {
 122         sigset_t sigmask, oldmask;
 123         thread_t newthread;
 124
 125         ASSERT(MUTEX_HELD(&umem_update_lock));
 126         ASSERT(umem_update_thr == 0);
 127
 128         /*
 129          * The update thread handles no signals
 130          */
 131         (void) sigfillset(&sigmask);
 132         (void) thr_sigsetmask(SIG_BLOCK, &sigmask, &oldmask);
 133
 134         /*
 135          * drop the umem_update_lock; we cannot hold locks acquired in
 136          * pre-fork handler while calling thr_create or thr_continue().
 137          */
 138
 139         (void) mutex_unlock(&umem_update_lock);
 140
 141         if (thr_create(NULL, NULL, umem_update_thread, NULL,
 142             THR_BOUND | THR_DAEMON | THR_DETACHED | THR_SUSPENDED,
 143             &newthread) == 0) {
 144                 (void) thr_sigsetmask(SIG_SETMASK, &oldmask, NULL);
 145
 146                 (void) mutex_lock(&umem_update_lock);
 147                 /*
 148                  * due to the locking in umem_reap(), only one thread can
 149                  * ever call umem_create_update_thread() at a time.  This
 150                  * must be the case for this code to work.
 151                  */
 152
 153                 ASSERT(umem_update_thr == 0);
 154                 umem_update_thr = newthread;
 155                 (void) mutex_unlock(&umem_update_lock);
 156                 (void) thr_continue(newthread);
 157                 (void) mutex_lock(&umem_update_lock);
 158
 159                 return (1);
 160         } else { /* thr_create failed */
 161                 (void) thr_sigsetmask(SIG_SETMASK, &oldmask, NULL);
 162                 (void) mutex_lock(&umem_update_lock);
 163         }
 164         return (0);
 165 }