| commit | 3d65c85f9187d311dbf1bf9e7fc2f5091a770853 | |
| author | Seth Jennings <sjenning@linux.vnet.ibm.com> | |
| Tue, 4 Oct 2011 13:21:32 +0000 (4 08:21 -0500) | ||
| committer | Greg Kroah-Hartman <gregkh@suse.de> | |
| Wed, 12 Oct 2011 15:29:03 +0000 (12 09:29 -0600) | ||
| tree | 37d2971a3f6f49693ae706d74e60c010b6ee45c4 | treesnapshot (tar.gz zip) |
| parent | fc2d6e573be68ac7b5a0730981fe9444ea2e2eaf | commitdiff |
staging: zcache: reduce tmem bucket lock contention
tmem uses hash buckets each with their own rbtree and lock to
quickly lookup tmem objects. tmem has TMEM_HASH_BUCKETS (256)
buckets per pool. However, because of the way the tmem_oid is
generated for frontswap pages, only 16 unique tmem_oids are being
generated, resulting in only 16 of the 256 buckets being used.
This cause high lock contention for the per bucket locks.
This patch changes SWIZ_BITS to include more bits of the offset.
The result is that all 256 hash buckets are potentially used resulting in a
95% drop in hash bucket lock contention.
Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
Acked-by: Dan Magenheimer <dan.magenheimer@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
tmem uses hash buckets each with their own rbtree and lock to
quickly lookup tmem objects. tmem has TMEM_HASH_BUCKETS (256)
buckets per pool. However, because of the way the tmem_oid is
generated for frontswap pages, only 16 unique tmem_oids are being
generated, resulting in only 16 of the 256 buckets being used.
This cause high lock contention for the per bucket locks.
This patch changes SWIZ_BITS to include more bits of the offset.
The result is that all 256 hash buckets are potentially used resulting in a
95% drop in hash bucket lock contention.
Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
Acked-by: Dan Magenheimer <dan.magenheimer@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
| drivers/staging/zcache/zcache-main.c | diffblobblamehistory |