linux-kernel - Re: problem with "sched: revert back to per-rq vruntime"?

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Message-ID: <495948E0.8040502@jaysonking.com>
Date:	Mon, 29 Dec 2008 16:02:08 -0600
From:	Jayson King <dev@...sonking.com>
To:	linux-kernel@...r.kernel.org
CC:	a.p.zijlstra@...llo.nl, mingo@...e.hu
Subject: Re: problem with "sched: revert back to per-rq vruntime"?

Sorry, forgot to CC Ingo & Peter as I intended. Resending. Please CC 
replies to me as I'm not on LKML.

-------- Original Message --------

Greetings,
(please CC replies to me)

After upgrading to 2.6.28 I noticed some latency problems. Mostly, bash 
and other programs would take a second or so to start where earlier it 
would start almost instantly. I have some nice'd tasks that use 100% of 
the CPU on each core of the Core 2 duo, and killing these tasks make the 
latency go away. But with older kernels these tasks did not cause 
latency problems.

I bisected it to f9c0b0950d5fd8c8c5af39bc061f27ea8fddcac3 
"sched: revert back to per-rq vruntime," and reverting it from 2.6.28 
fixes the latency.

Here is config and dmesg output of vanilla 2.6.28. System is x86_64 
Fedora 10. Let me know if there is additional details I can provide. Thanks.

Jayson

View attachment "dmesg-2.6.28" of type "text/plain" (71819 bytes)

View attachment ".config" of type "text/plain" (58585 bytes)