Re: Poor interactive performance with I/O loads with fsync()ing
From: Ric Wheeler
Date: Wed Apr 14 2010 - 14:41:45 EST
On 04/11/2010 05:22 PM, Dave Chinner wrote:
On Sun, Apr 11, 2010 at 08:16:09PM +0200, Thomas Gleixner wrote:
On Sun, 11 Apr 2010, Avi Kivity wrote:
On 04/09/2010 05:56 PM, Ben Gamari wrote:
On Mon, 29 Mar 2010 00:08:58 +0200, Andi Kleen<andi@xxxxxxxxxxxxxx> wrote:
Ben Gamari<bgamari.foss@xxxxxxxxx> writes:
ext4/XFS/JFS/btrfs should be better in this regard
I am using btrfs, so yes, I was expecting things to be better.
Unfortunately,
the improvement seems to be non-existent under high IO/fsync load.
btrfs is known to perform poorly under fsync.
XFS does not do much better. Just moved my VM images back to ext for
that reason.
Numbers? Workload description? Mount options? I hate it when all I
hear is "XFS sucked, so I went back to extN" reports without any
more details - it's hard to improve anything without any details
of the problems.
Also worth remembering is that XFS defaults to slow-but-safe
options, but ext3 defaults to fast-and-I-don't-give-a-damn-about-
data-safety, so there's a world of difference between the
filesystem defaults....
And FWIW, I run all my VMs on XFS using default mkfs and mount options,
and I can't say that I've noticed any performance problems at all
despite hammering the IO subsystems all the time. The only thing
I've ever done is occasionally run xfs_fsr across permanent qcow2
VM images to defrag them as the grow slowly over time...
Cheers,
Dave.
And if you are asking for details, the type of storage you use is also
quite interesting.
Thanks!
Ric
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