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authorMark Fasheh <mfasheh@suse.com>2010-04-05 18:17:14 -0700
committerJoel Becker <joel.becker@oracle.com>2010-05-05 18:18:07 -0700
commit6b82021b9e91cd689fdffadbcdb9a42597bbe764 (patch)
treeac4235e792e74a2e60a41e95d62965b7ed4b3232 /fs/ocfs2/super.c
parent73c8a80003d13be54e2309865030404441075182 (diff)
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 Also, I removed the OCFS2_DEFAULT_LOCAL_ALLOC_SIZE constant as it is no longer used and the comment above it was out of date.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/super.c')
-rw-r--r--fs/ocfs2/super.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/fs/ocfs2/super.c b/fs/ocfs2/super.c
index fc839996d052..5745682eb1c0 100644
--- a/fs/ocfs2/super.c
+++ b/fs/ocfs2/super.c
@@ -1503,7 +1503,7 @@ static int ocfs2_show_options(struct seq_file *s, struct vfsmount *mnt)
(unsigned) (osb->osb_commit_interval / HZ));
local_alloc_megs = osb->local_alloc_bits >> (20 - osb->s_clustersize_bits);
- if (local_alloc_megs != OCFS2_DEFAULT_LOCAL_ALLOC_SIZE)
+ if (local_alloc_megs != ocfs2_la_default_mb(osb))
seq_printf(s, ",localalloc=%d", local_alloc_megs);
if (opts & OCFS2_MOUNT_LOCALFLOCKS)
@@ -2251,6 +2251,7 @@ static int ocfs2_initialize_super(struct super_block *sb,
}
osb->bitmap_blkno = OCFS2_I(inode)->ip_blkno;
+ osb->osb_clusters_at_boot = OCFS2_I(inode)->ip_clusters;
iput(inode);
osb->bitmap_cpg = ocfs2_group_bitmap_size(sb) * 8;