From 1e8f915868c59be4d6e49d9aff928454a5d5d569 Mon Sep 17 00:00:00 2001 From: Wang Shilong Date: Mon, 6 May 2013 11:03:27 +0000 Subject: Btrfs: introduce qgroup_ulist to avoid frequently allocating/freeing ulist When doing qgroup accounting, we call ulist_alloc()/ulist_free() every time when we want to walk qgroup tree. By introducing 'qgroup_ulist', we only need to call ulist_alloc()/ulist_free() once. This reduce some sys time to allocate memory, see the measurements below fsstress -p 4 -n 10000 -d $dir With this patch: real 0m50.153s user 0m0.081s sys 0m6.294s real 0m51.113s user 0m0.092s sys 0m6.220s real 0m52.610s user 0m0.096s sys 0m6.125s avg 6.213 ----------------------------------------------------- Without the patch: real 0m54.825s user 0m0.061s sys 0m10.665s real 1m6.401s user 0m0.089s sys 0m11.218s real 1m13.768s user 0m0.087s sys 0m10.665s avg 10.849 we can see the sys time reduce ~43%. Signed-off-by: Wang Shilong Signed-off-by: Josef Bacik --- fs/btrfs/disk-io.c | 1 + 1 file changed, 1 insertion(+) (limited to 'fs/btrfs/disk-io.c') diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index aecf788ed81e..df5169b7aad1 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -2274,6 +2274,7 @@ int open_ctree(struct super_block *sb, fs_info->qgroup_seq = 1; fs_info->quota_enabled = 0; fs_info->pending_quota_state = 0; + fs_info->qgroup_ulist = NULL; mutex_init(&fs_info->qgroup_rescan_lock); btrfs_init_free_cluster(&fs_info->meta_alloc_cluster); -- cgit v1.2.3