From 6b82021b9e91cd689fdffadbcdb9a42597bbe764 Mon Sep 17 00:00:00 2001 From: Mark Fasheh Date: Mon, 5 Apr 2010 18:17:14 -0700 Subject: 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 Also, I removed the OCFS2_DEFAULT_LOCAL_ALLOC_SIZE constant as it is no longer used and the comment above it was out of date.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 Signed-off-by: Joel Becker --- fs/ocfs2/super.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'fs/ocfs2/super.c') 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; -- cgit v1.2.3