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/ctree.h | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'fs/btrfs/ctree.h') diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index d6dd49b51ba8..a365400e38da 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -1594,6 +1594,12 @@ struct btrfs_fs_info { struct rb_root qgroup_tree; spinlock_t qgroup_lock; + /* + * used to avoid frequently calling ulist_alloc()/ulist_free() + * when doing qgroup accounting, it must be protected by qgroup_lock. + */ + struct ulist *qgroup_ulist; + /* protect user change for quota operations */ struct mutex qgroup_ioctl_lock; -- cgit v1.2.3