--- /dev/null
+/*
+ * GPL HEADER START
+ *
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 only,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License version 2 for more details (a copy is included
+ * in the LICENSE file that accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License
+ * version 2 along with this program; If not, see
+ * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ *
+ * GPL HEADER END
+ */
+/*
+ * Copyright (c) 2007, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Use is subject to license terms.
+ *
+ * Copyright (c) 2011, 2012, Intel Corporation.
+ */
+/*
+ * This file is part of Lustre, http://www.lustre.org/
+ * Lustre is a trademark of Sun Microsystems, Inc.
+ *
+ * lnet/selftest/timer.c
+ *
+ * Author: Isaac Huang <isaac@clusterfs.com>
+ */
+
+#define DEBUG_SUBSYSTEM S_LNET
+
+#include "selftest.h"
+
+
+/*
+ * Timers are implemented as a sorted queue of expiry times. The queue
+ * is slotted, with each slot holding timers which expire in a
+ * 2**STTIMER_MINPOLL (8) second period. The timers in each slot are
+ * sorted by increasing expiry time. The number of slots is 2**7 (128),
+ * to cover a time period of 1024 seconds into the future before wrapping.
+ */
+#define STTIMER_MINPOLL 3 /* log2 min poll interval (8 s) */
+#define STTIMER_SLOTTIME (1 << STTIMER_MINPOLL)
+#define STTIMER_SLOTTIMEMASK (~(STTIMER_SLOTTIME - 1))
+#define STTIMER_NSLOTS (1 << 7)
+#define STTIMER_SLOT(t) (&stt_data.stt_hash[(((t) >> STTIMER_MINPOLL) & \
+ (STTIMER_NSLOTS - 1))])
+
+static struct st_timer_data {
+ spinlock_t stt_lock;
+ /* start time of the slot processed previously */
+ unsigned long stt_prev_slot;
+ struct list_head stt_hash[STTIMER_NSLOTS];
+ int stt_shuttingdown;
+ wait_queue_head_t stt_waitq;
+ int stt_nthreads;
+} stt_data;
+
+void
+stt_add_timer(stt_timer_t *timer)
+{
+ struct list_head *pos;
+
+ spin_lock(&stt_data.stt_lock);
+
+ LASSERT(stt_data.stt_nthreads > 0);
+ LASSERT(!stt_data.stt_shuttingdown);
+ LASSERT(timer->stt_func != NULL);
+ LASSERT(list_empty(&timer->stt_list));
+ LASSERT(cfs_time_after(timer->stt_expires, get_seconds()));
+
+ /* a simple insertion sort */
+ list_for_each_prev(pos, STTIMER_SLOT(timer->stt_expires)) {
+ stt_timer_t *old = list_entry(pos, stt_timer_t, stt_list);
+
+ if (cfs_time_aftereq(timer->stt_expires, old->stt_expires))
+ break;
+ }
+ list_add(&timer->stt_list, pos);
+
+ spin_unlock(&stt_data.stt_lock);
+}
+
+/*
+ * The function returns whether it has deactivated a pending timer or not.
+ * (ie. del_timer() of an inactive timer returns 0, del_timer() of an
+ * active timer returns 1.)
+ *
+ * CAVEAT EMPTOR:
+ * When 0 is returned, it is possible that timer->stt_func _is_ running on
+ * another CPU.
+ */
+int
+stt_del_timer(stt_timer_t *timer)
+{
+ int ret = 0;
+
+ spin_lock(&stt_data.stt_lock);
+
+ LASSERT(stt_data.stt_nthreads > 0);
+ LASSERT(!stt_data.stt_shuttingdown);
+
+ if (!list_empty(&timer->stt_list)) {
+ ret = 1;
+ list_del_init(&timer->stt_list);
+ }
+
+ spin_unlock(&stt_data.stt_lock);
+ return ret;
+}
+
+/* called with stt_data.stt_lock held */
+static int
+stt_expire_list(struct list_head *slot, unsigned long now)
+{
+ int expired = 0;
+ stt_timer_t *timer;
+
+ while (!list_empty(slot)) {
+ timer = list_entry(slot->next, stt_timer_t, stt_list);
+
+ if (cfs_time_after(timer->stt_expires, now))
+ break;
+
+ list_del_init(&timer->stt_list);
+ spin_unlock(&stt_data.stt_lock);
+
+ expired++;
+ (*timer->stt_func) (timer->stt_data);
+
+ spin_lock(&stt_data.stt_lock);
+ }
+
+ return expired;
+}
+
+static int
+stt_check_timers(unsigned long *last)
+{
+ int expired = 0;
+ unsigned long now;
+ unsigned long this_slot;
+
+ now = get_seconds();
+ this_slot = now & STTIMER_SLOTTIMEMASK;
+
+ spin_lock(&stt_data.stt_lock);
+
+ while (cfs_time_aftereq(this_slot, *last)) {
+ expired += stt_expire_list(STTIMER_SLOT(this_slot), now);
+ this_slot = cfs_time_sub(this_slot, STTIMER_SLOTTIME);
+ }
+
+ *last = now & STTIMER_SLOTTIMEMASK;
+ spin_unlock(&stt_data.stt_lock);
+ return expired;
+}
+
+
+static int
+stt_timer_main(void *arg)
+{
+ cfs_block_allsigs();
+
+ while (!stt_data.stt_shuttingdown) {
+ stt_check_timers(&stt_data.stt_prev_slot);
+
+ wait_event_timeout(stt_data.stt_waitq,
+ stt_data.stt_shuttingdown,
+ cfs_time_seconds(STTIMER_SLOTTIME));
+ }
+
+ spin_lock(&stt_data.stt_lock);
+ stt_data.stt_nthreads--;
+ spin_unlock(&stt_data.stt_lock);
+ return 0;
+}
+
+static int
+stt_start_timer_thread(void)
+{
+ struct task_struct *task;
+
+ LASSERT(!stt_data.stt_shuttingdown);
+
+ task = kthread_run(stt_timer_main, NULL, "st_timer");
+ if (IS_ERR(task))
+ return PTR_ERR(task);
+
+ spin_lock(&stt_data.stt_lock);
+ stt_data.stt_nthreads++;
+ spin_unlock(&stt_data.stt_lock);
+ return 0;
+}
+
+
+int
+stt_startup(void)
+{
+ int rc = 0;
+ int i;
+
+ stt_data.stt_shuttingdown = 0;
+ stt_data.stt_prev_slot = get_seconds() & STTIMER_SLOTTIMEMASK;
+
+ spin_lock_init(&stt_data.stt_lock);
+ for (i = 0; i < STTIMER_NSLOTS; i++)
+ INIT_LIST_HEAD(&stt_data.stt_hash[i]);
+
+ stt_data.stt_nthreads = 0;
+ init_waitqueue_head(&stt_data.stt_waitq);
+ rc = stt_start_timer_thread();
+ if (rc != 0)
+ CERROR("Can't spawn timer thread: %d\n", rc);
+
+ return rc;
+}
+
+void
+stt_shutdown(void)
+{
+ int i;
+
+ spin_lock(&stt_data.stt_lock);
+
+ for (i = 0; i < STTIMER_NSLOTS; i++)
+ LASSERT(list_empty(&stt_data.stt_hash[i]));
+
+ stt_data.stt_shuttingdown = 1;
+
+ wake_up(&stt_data.stt_waitq);
+ lst_wait_until(stt_data.stt_nthreads == 0, stt_data.stt_lock,
+ "waiting for %d threads to terminate\n",
+ stt_data.stt_nthreads);
+
+ spin_unlock(&stt_data.stt_lock);
+}
Code Review / kvmfornfv.git / blobdiff