diff options
| author | Raghavendra G <raghavendra@gluster.com> | 2009-10-28 04:46:25 +0000 |
|---|---|---|
| committer | Anand V. Avati <avati@dev.gluster.com> | 2009-10-29 10:07:49 -0700 |
| commit | 14962ce3e69e452a2447c12cde3369759365fda9 (patch) | |
| tree | 19702c29142c35e05a1548f9471c77f6a4eab05e /libglusterfs/src/common-utils.h | |
| parent | 13e6947744e8a26d2380af200942fd4ed61fd845 (diff) | |
performance/io-cache: change the hash function used for rbtree based hash table.
- the earlier hash function does not distribute pages uniformly for offsets that
fit into 32 bits. The reason is that the hash function just xors the contents of
the key 4 bytes at a time with the current value of hash. Hence for keys that
fit into 32 bits, the hash will be the key itself. Since we are using the
rounded_offset (which is a multiple of 128KB) as the key, the key will
be exactly divisible by the number of buckets configured (4096) resolving all
the pages into the first bucket.
Signed-off-by: Anand V. Avati <avati@dev.gluster.com>
BUG: 335 (Io-cache optimization)
URL: http://bugs.gluster.com/cgi-bin/bugzilla3/show_bug.cgi?id=335
Diffstat (limited to 'libglusterfs/src/common-utils.h')
| -rw-r--r-- | libglusterfs/src/common-utils.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/libglusterfs/src/common-utils.h b/libglusterfs/src/common-utils.h index c5869f4a424..48788d29545 100644 --- a/libglusterfs/src/common-utils.h +++ b/libglusterfs/src/common-utils.h @@ -330,6 +330,7 @@ int gf_lockfd (int fd); int gf_unlockfd (int fd); int get_checksum_for_file (int fd, uint32_t *checksum); +int gf_log2 (unsigned long x); #endif /* _COMMON_UTILS_H */ |