Re: PROBLEM: Heavy iowait on 2.6 kernels

[Guy Van Sanden]

My machine is heavily used for all kinds of file serving (mainly nfs),
but also samba.
Next to that, it is my home-server, so it runs apache2 (tuned to server
only few clients), imap (cyrus), postfix, bugzilla (mysql) and distcc
(used only a few times a week).
It replaces a FreeBSD system (PII-333) running the same except distcc.
Under 

The disk system is just a regular IDE disk (udma5) (60GB) and one
external drive over USB2 (160 GB).  The external drive is rather slow
(20-30 MB/sec), so I disabled it during the tests.

The weird thing is that I see this problem too when only running bonnie.
A friend of mine tried that too under 2.6.6, his iowait went up to
0.15%, mine to 99%.




On Wed, 2004-06-16 at 08:15, Clint Byrum wrote:
> On Fri, 2004-06-11 at 01:35, Guy Van Sanden wrote:
> > I recently discovered why my new Gentoo server slows to a crawl on a
> > intermediate load on the 2.6 kernel series.  The reason seems to be an
> > unusual amount of iowait.
> 
> This appears similar to the problem both myself and Phy Prahbab reported
> about 2.6 and hitting the disks too often. 
> 
> I'm wondering, what kind of workload does your machine see, and what
> sort of disk system is in it?
> 
> 
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-- 
______________________________________________________________________  

  Guy Van Sanden 
  http://unixmafia.port5.com  

  Registered Linux user #249404 - September 1997
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