Re: howto combat highly pathologic latencies on a server?

From: Hans-Peter Jansen
Date: Wed Mar 10 2010 - 19:28:22 EST


On Thursday 11 March 2010, 00:29:40 Dave Chinner wrote:
> On Wed, Mar 10, 2010 at 06:17:42PM +0100, Hans-Peter Jansen wrote:
> >
> > The xfs filesystems are mounted with rw,noatime,attr2,nobarrier,noquota
> > (yes, I do have a BBU on the areca, and disk write cache is effectively
> > turned off).
>
> Make sure the filesystem has the "lazy-count=1" attribute set (use
> xfs_info to check, xfs_admin to change). That will remove the
> superblock from most transactions and significant reduce latency of
> transactions as they serialise while locking it...

Dave, this modification sounds promising. Will do them during the weekend.
Also Christoph mentioned some pending patches for fdatasync and NFS metadata
updates in his XFS status report from February, that sounded _really_
exciting.

Happily awaiting these bits in the stable universe ;-)

Thanks,
Pete
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