tree 40c4db4b8b362496ef6365bb676cd3591e4de485
parent ecd1e64412d5242b8afdef58a714bab3c5464f79
author Jan Kara <jack@suse.cz> 1456162383 -0500
committer Theodore Ts'o <tytso@mit.edu> 1456162383 -0500

mbcache2: limit cache size

So far number of entries in mbcache is limited only by the pressure from
the shrinker. Since too many entries degrade the hash table and
generally we expect that caching more entries has diminishing returns,
limit number of entries the same way as in the old mbcache to 16 * hash
table size.

Once we exceed the desired maximum number of entries, we schedule a
backround work to reclaim entries. If the background work cannot keep up
and the number of entries exceeds two times the desired maximum, we
reclaim some entries directly when allocating a new entry.

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>