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Commit 6cf4cc8f authored by Joe Thornber's avatar Joe Thornber Committed by Mike Snitzer
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dm cache policy smq: stop preemptively demoting blocks 



It causes a lot of churn if the working set's size is close to the fast
device's size.

Signed-off-by: default avatarJoe Thornber <ejt@redhat.com>
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
parent 4d44ec5a

drivers/md/dm-cache-policy-smq.c

+5 −12
Original line number Diff line number Diff line
@@ -1134,13 +1134,10 @@ static bool clean_target_met(struct smq_policy *mq, bool idle) 
		percent_to_target(mq, CLEAN_TARGET);

}



static bool free_target_met(struct smq_policy *mq, bool idle)

static bool free_target_met(struct smq_policy *mq)

{

	unsigned nr_free;



	if (!idle)

		return true;



	nr_free = from_cblock(mq->cache_size) - mq->cache_alloc.nr_allocated;

	return (nr_free + btracker_nr_demotions_queued(mq->bg_work)) >=

		percent_to_target(mq, FREE_TARGET);
@@ -1220,7 +1217,7 @@ static void queue_promotion(struct smq_policy *mq, dm_oblock_t oblock, 
		 * We always claim to be 'idle' to ensure some demotions happen

		 * with continuous loads.

		 */

		if (!free_target_met(mq, true))

		if (!free_target_met(mq))

			queue_demotion(mq);

		return;

	}
@@ -1421,15 +1418,11 @@ static int smq_get_background_work(struct dm_cache_policy *p, bool idle, 
	spin_lock_irqsave(&mq->lock, flags);

	r = btracker_issue(mq->bg_work, result);

	if (r == -ENODATA) {

		/* find some writeback work to do */

		if (mq->migrations_allowed && !free_target_met(mq, idle))

			queue_demotion(mq);



		else if (!clean_target_met(mq, idle))

		if (!clean_target_met(mq, idle)) {

			queue_writeback(mq);



			r = btracker_issue(mq->bg_work, result);

		}

	}

	spin_unlock_irqrestore(&mq->lock, flags);



	return r;