dm bio prison: switch to using a red black tree
Previously it was using a fixed sized hash table. There are times
when very many concurrent cells are held (such as when processing a very
large discard). When this happens the hash table performance becomes
very poor.
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
diff --git a/drivers/md/dm-cache-target.c b/drivers/md/dm-cache-target.c
index 7130505..69de8b4 100644
--- a/drivers/md/dm-cache-target.c
+++ b/drivers/md/dm-cache-target.c
@@ -95,7 +95,6 @@
/*----------------------------------------------------------------*/
-#define PRISON_CELLS 1024
#define MIGRATION_POOL_SIZE 128
#define COMMIT_PERIOD HZ
#define MIGRATION_COUNT_WINDOW 10
@@ -2327,7 +2326,7 @@
INIT_DELAYED_WORK(&cache->waker, do_waker);
cache->last_commit_jiffies = jiffies;
- cache->prison = dm_bio_prison_create(PRISON_CELLS);
+ cache->prison = dm_bio_prison_create();
if (!cache->prison) {
*error = "could not create bio prison";
goto bad;