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authorFilipe Manana <fdmanana@suse.com>2015-03-31 14:16:52 +0100
committerChris Mason <clm@fb.com>2015-06-10 07:02:43 -0700
commitb659ef027792219b590d67a2baf1643a93727d29 (patch)
tree648b746a44cbbdb2b27d17dc10513a87496d9b88 /fs/btrfs/ordered-data.c
parent1ab818b137e198e4d06e987a4b089411f2e39d40 (diff)
downloadlinux-b659ef027792219b590d67a2baf1643a93727d29.tar.bz2
Btrfs: avoid syncing log in the fast fsync path when not necessary
Commit 3a8b36f37806 ("Btrfs: fix data loss in the fast fsync path") added a performance regression for that causes an unnecessary sync of the log trees (fs/subvol and root log trees) when 2 consecutive fsyncs are done against a file, without no writes or any metadata updates to the inode in between them and if a transaction is committed before the second fsync is called. Huang Ying reported this to lkml (https://lkml.org/lkml/2015/3/18/99) after a test sysbench test that measured a -62% decrease of file io requests per second for that tests' workload. The test is: echo performance > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor echo performance > /sys/devices/system/cpu/cpu1/cpufreq/scaling_governor echo performance > /sys/devices/system/cpu/cpu2/cpufreq/scaling_governor echo performance > /sys/devices/system/cpu/cpu3/cpufreq/scaling_governor mkfs -t btrfs /dev/sda2 mount -t btrfs /dev/sda2 /fs/sda2 cd /fs/sda2 for ((i = 0; i < 1024; i++)); do fallocate -l 67108864 testfile.$i; done sysbench --test=fileio --max-requests=0 --num-threads=4 --max-time=600 \ --file-test-mode=rndwr --file-total-size=68719476736 --file-io-mode=sync \ --file-num=1024 run A test on kvm guest, running a debug kernel gave me the following results: Without 3a8b36f378060d: 16.01 reqs/sec With 3a8b36f378060d: 3.39 reqs/sec With 3a8b36f378060d and this patch: 16.04 reqs/sec Reported-by: Huang Ying <ying.huang@intel.com> Tested-by: Huang, Ying <ying.huang@intel.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Chris Mason <clm@fb.com>
Diffstat (limited to 'fs/btrfs/ordered-data.c')
-rw-r--r--fs/btrfs/ordered-data.c14
1 files changed, 14 insertions, 0 deletions
diff --git a/fs/btrfs/ordered-data.c b/fs/btrfs/ordered-data.c
index 47966cb3d4b6..ceccd078c93d 100644
--- a/fs/btrfs/ordered-data.c
+++ b/fs/btrfs/ordered-data.c
@@ -837,6 +837,20 @@ out:
return entry;
}
+bool btrfs_have_ordered_extents_in_range(struct inode *inode,
+ u64 file_offset,
+ u64 len)
+{
+ struct btrfs_ordered_extent *oe;
+
+ oe = btrfs_lookup_ordered_range(inode, file_offset, len);
+ if (oe) {
+ btrfs_put_ordered_extent(oe);
+ return true;
+ }
+ return false;
+}
+
/*
* lookup and return any extent before 'file_offset'. NULL is returned
* if none is found