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| author | Filipe David Borba Manana <fdmanana@gmail.com> | 2013-11-22 18:54:58 +0000 |
|---|---|---|
| committer | Chris Mason <clm@fb.com> | 2014-01-28 13:19:46 -0800 |
| commit | 1b8e7e45e57cc98bf6c8ab9b3087d634636ba2e6 (patch) | |
| tree | a0bb4d9f935619abe151ad772ee7dbec83b05365 /fs | |
| parent | e453d989e0bb33defaaa5be4e9f577cea946e2a6 (diff) | |
Btrfs: avoid unnecessary ordered extent cache resets
After an ordered extent completes, don't blindly reset the
inode's ordered tree last accessed ordered extent pointer.
While running the xfstests I noticed that about 29% of the
time the ordered extent to which tree->last pointed was not
the same as our just completed ordered extent. After that I
ran the following sysbench test (after a prepare phase) and
noticed that about 68% of the time tree->last pointed to
a different ordered extent too.
sysbench --test=fileio --file-num=32 --file-total-size=4G \
--file-test-mode=rndwr --num-threads=512 \
--file-block-size=32768 --max-time=60 --max-requests=0 run
Therefore reset tree->last on ordered extent removal only if
it pointed to the ordered extent we're removing from the tree.
Results from 4 runs of the following test before and after
applying this patch:
$ sysbench --test=fileio --file-num=32 --file-total-size=4G \
--file-test-mode=seqwr --num-threads=512 \
--file-block-size=32768 --max-time=60 --file-io-mode=sync prepare
$ sysbench --test=fileio --file-num=32 --file-total-size=4G \
--file-test-mode=seqwr --num-threads=512 \
--file-block-size=32768 --max-time=60 --file-io-mode=sync run
Before this path:
run 1 - 64.049Mb/sec
run 2 - 63.455Mb/sec
run 3 - 64.656Mb/sec
run 4 - 63.833Mb/sec
After this patch:
run 1 - 66.149Mb/sec
run 2 - 68.459Mb/sec
run 3 - 66.338Mb/sec
run 4 - 66.176Mb/sec
With random writes (--file-test-mode=rndwr) I had huge fluctuations
on the results (+- 35% easily).
Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Chris Mason <clm@fb.com>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/btrfs/ordered-data.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/fs/btrfs/ordered-data.c b/fs/btrfs/ordered-data.c index 69582d5b69d1..b8c2ded75fe2 100644 --- a/fs/btrfs/ordered-data.c +++ b/fs/btrfs/ordered-data.c @@ -520,7 +520,8 @@ void btrfs_remove_ordered_extent(struct inode *inode, spin_lock_irq(&tree->lock); node = &entry->rb_node; rb_erase(node, &tree->tree); - tree->last = NULL; + if (tree->last == node) + tree->last = NULL; set_bit(BTRFS_ORDERED_COMPLETE, &entry->flags); spin_unlock_irq(&tree->lock); |