From 2e63309507c818e8b631a03f02c363031c007fb7 Mon Sep 17 00:00:00 2001 From: Joe Thornber Date: Thu, 11 May 2017 09:09:04 -0400 Subject: [PATCH] dm cache policy smq: don't do any writebacks unless IDLE If there are no clean blocks to be demoted the writeback will be triggered at that point. Preemptively writing back can hurt high IO load scenarios. Signed-off-by: Joe Thornber Signed-off-by: Mike Snitzer --- drivers/md/dm-cache-policy-smq.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/drivers/md/dm-cache-policy-smq.c b/drivers/md/dm-cache-policy-smq.c index 758480a..e5eb9c9 100644 --- a/drivers/md/dm-cache-policy-smq.c +++ b/drivers/md/dm-cache-policy-smq.c @@ -1120,8 +1120,6 @@ static bool clean_target_met(struct smq_policy *mq, bool idle) * Cache entries may not be populated. So we cannot rely on the * size of the clean queue. */ - unsigned nr_clean; - if (idle) { /* * We'd like to clean everything. @@ -1129,9 +1127,10 @@ static bool clean_target_met(struct smq_policy *mq, bool idle) return q_size(&mq->dirty) == 0u; } - nr_clean = from_cblock(mq->cache_size) - q_size(&mq->dirty); - return (nr_clean + btracker_nr_writebacks_queued(mq->bg_work)) >= - percent_to_target(mq, CLEAN_TARGET); + /* + * If we're busy we don't worry about cleaning at all. + */ + return true; } static bool free_target_met(struct smq_policy *mq) -- 2.7.4