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Subject: Re: [RFC patch 1/2] sched: dynamically adapt granularity with
 nr_running
From: Mike Galbraith <efault@gmx.de>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>, Ingo Molnar <mingo@elte.hu>,
        Steven Rostedt <rostedt@goodmis.org>,
        Thomas Gleixner <tglx@linutronix.de>, Tony Lindgren <tony@atomide.com>
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Date: Mon, 13 Sep 2010 06:35:47 +0200
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On Sun, 2010-09-12 at 11:06 +0200, Peter Zijlstra wrote:
> On Sat, 2010-09-11 at 13:48 -0700, Linus Torvalds wrote:

> > And I don't like how you dismissed the measured latency improvement.
> > And yes, I do think latency matters. A _lot_.
> 
> OK, we'll make it better and sacrifice some throughput, can do, no
> problem.

I'm not seeing high wakeup latencies, even under hefty load.  Mathieu's
testcase is bad, but apparently solely due to START_DEBIT placement.
That's kind of a sticky wicket.  I've shot it in the heart before, but
regretted doing so when I looked at kbuild vs static load fairness.

	-Mike