cost of tdb transactions on ext4 with barriers
idra at samba.org
Fri Feb 12 06:47:55 MST 2010
On Fri, 2010-02-12 at 12:44 +1100, tridge at samba.org wrote:
> Hi Rusty,
> for completeness, here is are the results including the btrfs and xfs
> ext3 barrier=0 1.9s
> ext3 barrier=1 13.4s
can you try the above test with data=ordered ?
AFAIK ext4 has that option on by default.
> ext4 barrier=0 2.5s
> ext4 barrier=1 36.0s
> btrfs nobarrier 29.1s
> btrfs barrier=1 117s
> xfs 8.9s
I am told xfs dumps to disk only the data related to the specific
fsync(), while ext3 (and probably ext4) dump *everything*, even
unrelated data, to disk on fsync.
Btrfs should do the right thing in time, but I assume the version youare
running is not quite prime time ready or tuned.
> (the barrier options make no difference on xfs as far as I can see).
> If ext4 and btrfs are the future of Linux filesystems then tdb/Samba
> are in real trouble!
I don't think the current data you have btrfs really represent the
performance of btrfs when it will be ready. However I am told that
btrfs's COW may be a problem, and lots of data rewrites amy be a worst
case scenario for btrfs.
Can you test btrfs with nodatacow ?
Samba Team GPL Compliance Officer <simo at samba.org>
Principal Software Engineer at Red Hat, Inc. <simo at redhat.com>
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