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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: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This commit is contained in:
Joe Thornber 2017-11-09 11:41:05 -05:00 committed by Mike Snitzer
parent 8ee18ede74
commit 9768a10dd3
1 changed files with 14 additions and 1 deletions
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15
drivers/md/dm-cache-policy-smq.c
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@ -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++;