Re: observed significant performance improvement using "delaylog" in a real-world application

[Dave Chinner <david@fromorbit.com>]

On Tue, Aug 10, 2010 at 06:01:33PM +0200, Peter Niemayer wrote:
> Hi all,
> 
> we use XFS for a very I/O-intensive, in-house developed real-time
> database application, and whenever we see new or significantly
> changed file-systems becoming available, we run a benchmark using
> this application on a conserved, fixed real-world data set.
> 
> I'm pleased to state that using the experimental "delaylog" mount
> option (in vanilla linux-2.6.35) we measured a 17% performance
> increase
> for our benchmark scenario. (Other mount-options in use both before
> and after the "delaylog" option: noatime,nodiratime,nobarrier)

That's great to hear. One thing that you might want to try to
further improve performance is the logbsize=262144 option as well.
That will help flush log IO faster by doing less IOs.

Also, if your workload is doing lots of fsync calls, then the
optimisations I posted a few days ago should also help improve
delaylog throughput.

> That's a lot given that XFS was the fastest performing file-system
> for this application already.
> 
> It's also a promising result regarding stability, as several other
> tests (using e.g. reiser4 or ceph) in the past led to crashes in the
> same benchmark scenario.

That's definitely encouraging. ;)

> So thanks to all contributing developers for this significant optimization!

And thanks for the feedback.

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

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