linux-kernel - Re: netperf ~50% regression with 2.6.33-rc1, bisect to 1b9508f

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Message-Id: <1264419913.5888.49.camel@marge.simson.net>
Date:	Mon, 25 Jan 2010 12:45:13 +0100
From:	Mike Galbraith <efault@....de>
To:	Lin Ming <ming.m.lin@...el.com>
Cc:	Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...e.hu>,
	"Zhang, Yanmin" <yanmin_zhang@...ux.intel.com>,
	lkml <linux-kernel@...r.kernel.org>
Subject: Re: netperf ~50% regression with 2.6.33-rc1, bisect to 1b9508f

On Mon, 2010-01-25 at 12:35 +0100, Mike Galbraith wrote:

> So.  Rummaging around doing absolutely _nothing_ useful, there being
> zero movable tasks in this load, prevents us switching to the idle
> thread before the scheduling task is requeued.  Oh joy.

Wait a minute.  The only way that can work is if we hit contended lock,
and drop our rq lock (and where would busiest->nr_running > 1 come from
with a 2 task load?)

Puzzled.

	-Mike

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