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| author | Mark Fasheh <mfasheh@suse.com> | 2010-04-06 03:17:14 +0200 |
|---|---|---|
| committer | Joel Becker <joel.becker@oracle.com> | 2010-05-06 03:18:07 +0200 |
| commit | 6b82021b9e91cd689fdffadbcdb9a42597bbe764 (patch) | |
| tree | ac4235e792e74a2e60a41e95d62965b7ed4b3232 /fs/ocfs2/ocfs2.h | |
| parent | ocfs2: clean up localalloc mount option size parsing (diff) | |
| download | linux-6b82021b9e91cd689fdffadbcdb9a42597bbe764.tar.xz linux-6b82021b9e91cd689fdffadbcdb9a42597bbe764.zip | |
ocfs2: increase the default size of local alloc windows
I have observed that the current size of 8M gives us pretty poor
fragmentation on multi-threaded workloads which do lots of writes.
Generally, I can increase the size of local alloc windows and observe a
marked decrease in fragmentation, even up and beyond window sizes of 512
megabytes. This makes sense for a couple reasons - larger local alloc means
more room for reservation windows. On multi-node workloads the larger local
alloc helps as well because we don't have to do window slides as often.
Also, I removed the OCFS2_DEFAULT_LOCAL_ALLOC_SIZE constant as it is no
longer used and the comment above it was out of date.
To test fragmentation, I used a workload which launched 4 threads that did
4k writes into a series of about 140 alternating files.
With resv_level=2, and a 4k/4k file system I observed the following average
fragmentation for various localalloc= parameters:
localalloc= avg. fragmentation
8 48
32 16
64 10
120 7
On larger cluster sizes, the difference is more dramatic.
The new default size top out at 256M, which we'll only get for cluster
sizes of 32K and above.
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
Diffstat (limited to 'fs/ocfs2/ocfs2.h')
| -rw-r--r-- | fs/ocfs2/ocfs2.h | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/fs/ocfs2/ocfs2.h b/fs/ocfs2/ocfs2.h index e98c954cf961..09d7aee3dabe 100644 --- a/fs/ocfs2/ocfs2.h +++ b/fs/ocfs2/ocfs2.h @@ -342,6 +342,9 @@ struct ocfs2_super */ unsigned int local_alloc_bits; unsigned int local_alloc_default_bits; + /* osb_clusters_at_boot can become stale! Do not trust it to + * be up to date. */ + unsigned int osb_clusters_at_boot; enum ocfs2_local_alloc_state local_alloc_state; /* protected * by osb_lock */ |