dm raid1: use timer
This patch replaces the schedule() in the main kmirrord thread with a timer.
The schedule() could introduce an unwanted delay when work is ready to be
processed.
The code instead calls wake() when there's work to be done immediately, and
delayed_wake() after a failure to give a short delay before retrying.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
diff --git a/drivers/md/dm-raid1.c b/drivers/md/dm-raid1.c
index 6692e5a..3b9532f 100644
--- a/drivers/md/dm-raid1.c
+++ b/drivers/md/dm-raid1.c
@@ -154,6 +154,9 @@
struct workqueue_struct *kmirrord_wq;
struct work_struct kmirrord_work;
+ struct timer_list timer;
+ unsigned long timer_pending;
+
struct work_struct trigger_event;
unsigned int nr_mirrors;
@@ -178,6 +181,25 @@
queue_work(ms->kmirrord_wq, &ms->kmirrord_work);
}
+static void delayed_wake_fn(unsigned long data)
+{
+ struct mirror_set *ms = (struct mirror_set *) data;
+
+ clear_bit(0, &ms->timer_pending);
+ wake(ms);
+}
+
+static void delayed_wake(struct mirror_set *ms)
+{
+ if (test_and_set_bit(0, &ms->timer_pending))
+ return;
+
+ ms->timer.expires = jiffies + HZ / 5;
+ ms->timer.data = (unsigned long) ms;
+ ms->timer.function = delayed_wake_fn;
+ add_timer(&ms->timer);
+}
+
/* FIXME move this */
static void queue_bio(struct mirror_set *ms, struct bio *bio, int rw);
@@ -1180,6 +1202,7 @@
spin_lock_irq(&ms->lock);
bio_list_merge(&ms->failures, &sync);
spin_unlock_irq(&ms->lock);
+ wake(ms);
} else
while ((bio = bio_list_pop(&sync)))
do_write(ms, bio);
@@ -1239,7 +1262,7 @@
bio_list_merge(&ms->failures, failures);
spin_unlock_irq(&ms->lock);
- wake(ms);
+ delayed_wake(ms);
}
static void trigger_event(struct work_struct *work)
@@ -1253,7 +1276,7 @@
/*-----------------------------------------------------------------
* kmirrord
*---------------------------------------------------------------*/
-static int _do_mirror(struct work_struct *work)
+static void do_mirror(struct work_struct *work)
{
struct mirror_set *ms =container_of(work, struct mirror_set,
kmirrord_work);
@@ -1274,24 +1297,6 @@
do_reads(ms, &reads);
do_writes(ms, &writes);
do_failures(ms, &failures);
-
- return (ms->failures.head) ? 1 : 0;
-}
-
-static void do_mirror(struct work_struct *work)
-{
- /*
- * If _do_mirror returns 1, we give it
- * another shot. This helps for cases like
- * 'suspend' where we call flush_workqueue
- * and expect all work to be finished. If
- * a failure happens during a suspend, we
- * couldn't issue a 'wake' because it would
- * not be honored. Therefore, we return '1'
- * from _do_mirror, and retry here.
- */
- while (_do_mirror(work))
- schedule();
}
@@ -1545,6 +1550,8 @@
goto err_free_context;
}
INIT_WORK(&ms->kmirrord_work, do_mirror);
+ init_timer(&ms->timer);
+ ms->timer_pending = 0;
INIT_WORK(&ms->trigger_event, trigger_event);
r = parse_features(ms, argc, argv, &args_used);
@@ -1587,6 +1594,7 @@
{
struct mirror_set *ms = (struct mirror_set *) ti->private;
+ del_timer_sync(&ms->timer);
flush_workqueue(ms->kmirrord_wq);
dm_kcopyd_client_destroy(ms->kcopyd_client);
destroy_workqueue(ms->kmirrord_wq);