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authorJoe Thornber <ejt@redhat.com>2016-09-15 09:36:24 -0400
committerMike Snitzer <snitzer@redhat.com>2016-09-22 11:15:03 -0400
commit9d1b404cbc3f990a4035dcf7ddd37adac2a99b3f (patch)
treee3afe884a02e400cf69d8e10f809b218d772b564 /drivers/md/dm-cache-policy-smq.c
parent4e781b498ee5008ede91362d91404a362e7a46b3 (diff)
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dm cache policy smq: distribute entries to random levels when switching to smq
For smq the 32 bit 'hint' stores the multiqueue level that the entry should be stored in. If a different policy has been used previously, and then switched to smq, the hints will be invalid. In which case we used to put all entries in the bottom level of the multiqueue, and then redistribute. Redistribution is faster if we put entries with invalid hints in random levels initially. Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Diffstat (limited to 'drivers/md/dm-cache-policy-smq.c')
-rw-r--r--drivers/md/dm-cache-policy-smq.c7
1 files changed, 6 insertions, 1 deletions
diff --git a/drivers/md/dm-cache-policy-smq.c b/drivers/md/dm-cache-policy-smq.c
index f3cec4e6333c..c33f4a6e1d7d 100644
--- a/drivers/md/dm-cache-policy-smq.c
+++ b/drivers/md/dm-cache-policy-smq.c
@@ -1359,6 +1359,11 @@ static void smq_clear_dirty(struct dm_cache_policy *p, dm_oblock_t oblock)
spin_unlock_irqrestore(&mq->lock, flags);
}
+static unsigned random_level(dm_cblock_t cblock)
+{
+ return hash_32_generic(from_cblock(cblock), 9) & (NR_CACHE_LEVELS - 1);
+}
+
static int smq_load_mapping(struct dm_cache_policy *p,
dm_oblock_t oblock, dm_cblock_t cblock,
uint32_t hint, bool hint_valid)
@@ -1369,7 +1374,7 @@ static int smq_load_mapping(struct dm_cache_policy *p,
e = alloc_particular_entry(&mq->cache_alloc, from_cblock(cblock));
e->oblock = oblock;
e->dirty = false; /* this gets corrected in a minute */
- e->level = hint_valid ? min(hint, NR_CACHE_LEVELS - 1) : 1;
+ e->level = hint_valid ? min(hint, NR_CACHE_LEVELS - 1) : random_level(cblock);
push(mq, e);
return 0;