linux-kernel - Network slowdown due to CFS

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Message-ID: <20070926085202.GE3337@deprecation.cyrius.com>
Date:	Wed, 26 Sep 2007 10:52:02 +0200
From:	Martin Michlmayr <tbm@...ius.com>
To:	Ingo Molnar <mingo@...e.hu>,
	Srivatsa Vaddagiri <vatsa@...ux.vnet.ibm.com>
Cc:	linux-kernel@...r.kernel.org
Subject: Network slowdown due to CFS

I noticed that my network performance has gone down from 2.6.22
from   [  3]  0.0-10.0 sec    113 MBytes  95.0 Mbits/sec
to     [  3]  0.0-10.0 sec   75.7 MBytes  63.3 Mbits/sec
with 2.6.23-rc1 (and 2.6.23-rc8), as measured with iperf.

I did a git bisect today and tracked it back to the commit where CFS
was enabled ("sched: cfs core code; apply the CFS core code",
commit dd41f596cda0d7d6e4a8b139ffdfabcefdd46528).  I also compiled a
kernel from
git://git.kernel.org/pub/scm/linux/kernel/git/mingo/linux-2.6-sched-devel.git
but things don't improve.

This is on a Thecus N2100, an ARM (Intel IOP32x) based storage device
with a r8169 card, SATA disks and 512 MB RAM.  My config is attached.

What kind of information can I supply so you can track this down?
-- 
Martin Michlmayr
http://www.cyrius.com/

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