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dm raid1: use timer

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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>
This commit is contained in:
Mikulas Patocka 2008-04-24 22:10:42 +01:00 committed by Alasdair G Kergon
parent a765e20eeb
commit a2aebe03be
1 changed files with 28 additions and 20 deletions
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48
drivers/md/dm-raid1.c
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@ -154,6 +154,9 @@ struct mirror_set {
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 @@ static void wake(struct mirror_set *ms)
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 @@ static void do_writes(struct mirror_set *ms, struct bio_list *writes)
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 @@ static void do_failures(struct mirror_set *ms, struct bio_list *failures)
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 @@ static void trigger_event(struct work_struct *work)
/*-----------------------------------------------------------------
* 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 @@ static int _do_mirror(struct work_struct *work)
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 @@ static int mirror_ctr(struct dm_target *ti, unsigned int argc, char **argv)
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 @@ static void mirror_dtr(struct dm_target *ti)
{
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);