diff options
| author | Qu Wenruo <wqu@suse.com> | 2018-09-27 14:42:33 +0800 |
|---|---|---|
| committer | David Sterba <dsterba@suse.com> | 2018-10-15 17:23:36 +0200 |
| commit | 2cd86d309bd1203241ceb833effe90787f3564a1 (patch) | |
| tree | e4ed59844c55b5f2e9804400f41d7f2f776473fd /fs/btrfs | |
| parent | 5f527822be40104e9056c981ff06c7750153a10a (diff) | |
btrfs: qgroup: Don't trace subtree if we're dropping reloc tree
Reloc tree doesn't contribute to qgroup numbers, as we have accounted
them at balance time (see replace_path()).
Skipping the unneeded subtree tracing should reduce the overhead.
[[Benchmark]]
Hardware:
VM 4G vRAM, 8 vCPUs,
disk is using 'unsafe' cache mode,
backing device is SAMSUNG 850 evo SSD.
Host has 16G ram.
Mkfs parameter:
--nodesize 4K (To bump up tree size)
Initial subvolume contents:
4G data copied from /usr and /lib.
(With enough regular small files)
Snapshots:
16 snapshots of the original subvolume.
each snapshot has 3 random files modified.
balance parameter:
-m
So the content should be pretty similar to a real world root fs layout.
| v4.19-rc1 | w/ patchset | diff (*)
---------------------------------------------------------------
relocated extents | 22929 | 22900 | -0.1%
qgroup dirty extents | 227757 | 167139 | -26.6%
time (sys) | 65.253s | 50.123s | -23.2%
time (real) | 74.032s | 52.551s | -29.0%
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs')
| -rw-r--r-- | fs/btrfs/extent-tree.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index 8798fa029ebe..d68ee91c00fc 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -8683,7 +8683,13 @@ skip: parent = 0; } - if (need_account) { + /* + * Reloc tree doesn't contribute to qgroup numbers, and we have + * already accounted them at merge time (replace_path), + * thus we could skip expensive subtree trace here. + */ + if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID && + need_account) { ret = btrfs_qgroup_trace_subtree(trans, next, generation, level - 1); if (ret) { |