Attachment 314575 Details for Bug 438153 – first patch

[patch] first patch

linux-2.6.18-dm-slow-mirror.patch (text/plain), 3.62 KB, created by Mikuláš Patočka on 2008-08-19 21:09:18 UTC

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Creator: Mikuláš Patočka

Created: 2008-08-19 21:09:18 UTC

Size: 3.62 KB

patch

obsolete

>Upstream commit: a2aebe03be60ae4da03507a00d60211d5e0327c3 (2.6.26-rc1)
>
>Fix bugzilla 438153.
>
>Using schedule() or schedule_timeout() (which used to be there) would block
>the process and degrade performance.
>
>I reworked the code to use timer: after adding something to queues, the code
>must call either wake (process the queue immediatelly) or delayed_wake (process
>the queue after at most 1/5s).
>
>Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
>
>---
>
>diff -p -u -r linux-2.6.18.x86_64.p1/drivers/md/dm-raid1.c linux-2.6.18.x86_64/drivers/md/dm-raid1.c
>--- linux-2.6.18.x86_64.p1/drivers/md/dm-raid1.c	2008-08-18 14:06:36.000000000 +0200
>+++ linux-2.6.18.x86_64/drivers/md/dm-raid1.c	2008-08-18 15:57:05.000000000 +0200
>@@ -145,6 +145,9 @@ struct mirror_set {
> 	struct workqueue_struct *kmirrord_wq;
> 	struct work_struct kmirrord_work;
> 
>+	struct timer_list timer;
>+	unsigned long timer_pending;
>+
> 	struct mirror mirror[0];
> };
> 
>@@ -656,6 +659,23 @@ static void bio_map_info_free(void *elem
> 	kfree(element);
> }
> 
>+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)) {
>+		ms->timer.expires = jiffies + HZ / 5;
>+		ms->timer.data = (unsigned long)ms;
>+		ms->timer.function = delayed_wake_fn;
>+		add_timer(&ms->timer);
>+	}
>+}
>+
> /*
>  * Every mirror should look like this one.
>  */
>@@ -1184,9 +1204,12 @@ static void do_writes(struct mirror_set 
> 	 * Add bios that are delayed due to remote recovery
> 	 * back on to the write queue
> 	 */
>-	spin_lock_irq(&ms->lock);
>-	bio_list_merge(&ms->writes, &requeue);
>-	spin_unlock_irq(&ms->lock);
>+	if (requeue.head) {
>+		spin_lock_irq(&ms->lock);
>+		bio_list_merge(&ms->writes, &requeue);
>+		spin_unlock_irq(&ms->lock);
>+		delayed_wake(ms);
>+	}
> 
> 	/*
> 	 * Increment the pending counts for any regions that will
>@@ -1205,6 +1228,7 @@ static void do_writes(struct mirror_set 
> 		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);
>@@ -1255,7 +1279,7 @@ static void do_failures(struct mirror_se
> 			spin_lock_irq(&ms->lock);
> 			bio_list_merge(&ms->failures, failures);
> 			spin_unlock_irq(&ms->lock);
>-			wake(ms);
>+			delayed_wake(ms);
> 		}
> 		return;
> 	}
>@@ -1270,7 +1294,7 @@ static void do_failures(struct mirror_se
> /*-----------------------------------------------------------------
>  * kmirrord
>  *---------------------------------------------------------------*/
>-static int do_mirror(struct mirror_set *ms)
>+static void do_mirror(struct mirror_set *ms)
> {
> 	struct bio_list reads, writes, failures;
> 
>@@ -1288,14 +1312,11 @@ static int do_mirror(struct mirror_set *
> 	do_reads(ms, &reads);
> 	do_writes(ms, &writes);
> 	do_failures(ms, &failures);
>-
>-	return (ms->writes.head || ms->failures.head) ? 1 : 0;
> }
> 
> static void do_work(void *data)
> {
>-	while (do_mirror(data))
>-		schedule();
>+	do_mirror(data);
> }
> 
> /*-----------------------------------------------------------------
>@@ -1500,6 +1521,8 @@ static int mirror_ctr(struct dm_target *
> 		return -ENOMEM;
> 	}
> 	INIT_WORK(&ms->kmirrord_work, do_work, ms);
>+	init_timer(&ms->timer);
>+	ms->timer_pending = 0;
> 
> 	r = kcopyd_client_create(DM_IO_PAGES, &ms->kcopyd_client);
> 	if (r) {
>@@ -1516,6 +1539,7 @@ static void mirror_dtr(struct dm_target 
> {
> 	struct mirror_set *ms = (struct mirror_set *) ti->private;
> 
>+	del_timer_sync(&ms->timer);
> 	flush_workqueue(ms->kmirrord_wq);
> 	kcopyd_client_destroy(ms->kcopyd_client);
> 	destroy_workqueue(ms->kmirrord_wq);

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