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Commit 9768a10d authored by Joe Thornber's avatar Joe Thornber Committed by Mike Snitzer
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dm cache policy smq: allocate cache blocks in order 



Previously, cache blocks were being allocated in reverse order.  Fix
this by pulling the block off the head of the free list.

Shouldn't have any impact on performance or latency but it is more
correct to have the cache blocks allocated/mapped in ascending order.
This fix will slightly increase the chances of two adjacent oblocks
being in adjacent cblocks.

Signed-off-by: default avatarJoe Thornber <ejt@redhat.com>
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
parent 8ee18ede

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

+14 −1
Original line number Diff line number Diff line
@@ -213,6 +213,19 @@ static void l_del(struct entry_space *es, struct ilist *l, struct entry *e) 
		l->nr_elts--;

}



static struct entry *l_pop_head(struct entry_space *es, struct ilist *l)

{

	struct entry *e;



	for (e = l_head(es, l); e; e = l_next(es, e))

		if (!e->sentinel) {

			l_del(es, l, e);

			return e;

		}



	return NULL;

}



static struct entry *l_pop_tail(struct entry_space *es, struct ilist *l)

{

	struct entry *e;
@@ -719,7 +732,7 @@ static struct entry *alloc_entry(struct entry_alloc *ea) 
	if (l_empty(&ea->free))

		return NULL;



	e = l_pop_tail(ea->es, &ea->free);

	e = l_pop_head(ea->es, &ea->free);

	init_entry(e);

	ea->nr_allocated++;