From: Joe Thornber <ejt@redhat.com>
Date: Fri, 10 May 2013 13:37:16 +0000 (+0100)
Subject: dm cache: tune migration throttling
X-Git-Tag: android-x86-4.4-r1~780^2~14
X-Git-Url: http://git.osdn.net/view?a=commitdiff_plain;h=f8350daf7af05e3b8cf98e9550de3f623af03fe7;p=android-x86%2Fkernel.git

dm cache: tune migration throttling

Tune the dm cache migration throttling.

i) Issue a tick every second, just in case there's no i/o going through.

ii) Drop the migration threshold right down to something suitable for
background work.

Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
---

diff --git a/drivers/md/dm-cache-target.c b/drivers/md/dm-cache-target.c
index 6feaba24fcac..c3c18527da39 100644
--- a/drivers/md/dm-cache-target.c
+++ b/drivers/md/dm-cache-target.c
@@ -1445,6 +1445,7 @@ static void do_worker(struct work_struct *ws)
 static void do_waker(struct work_struct *ws)
 {
 	struct cache *cache = container_of(to_delayed_work(ws), struct cache, waker);
+	policy_tick(cache->policy);
 	wake_worker(cache);
 	queue_delayed_work(cache->wq, &cache->waker, COMMIT_PERIOD);
 }
@@ -1886,7 +1887,7 @@ static sector_t calculate_discard_block_size(sector_t cache_block_size,
 	return discard_block_size;
 }
 
-#define DEFAULT_MIGRATION_THRESHOLD (2048 * 100)
+#define DEFAULT_MIGRATION_THRESHOLD 2048
 
 static int cache_create(struct cache_args *ca, struct cache **result)
 {