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Subject: Re: [RFC patch 1/2] sched: dynamically adapt granularity with
 nr_running
From: Peter Zijlstra <peterz@infradead.org>
To: Mike Galbraith <efault@gmx.de>
Cc: Ingo Molnar <mingo@elte.hu>,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
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Date: Mon, 13 Sep 2010 11:37:40 +0200
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On Mon, 2010-09-13 at 11:16 +0200, Mike Galbraith wrote:
> On Mon, 2010-09-13 at 10:35 +0200, Peter Zijlstra wrote:
> > On Mon, 2010-09-13 at 09:08 +0200, Mike Galbraith wrote:
> > > We need a better fork fairness gizmo.
> > 
> > Proper zero-lag insertion would do. Much sadness in that tracking that
> > costs a u64 mult per enqueu/dequeue and using it adds a s64 div.
> 
> (math _sucks_:)
> 
> > But if you want, have a play with:
> 
> maximum latency: 48475.3 µs
> average latency: 6881.4 µs
> missed timer events: 0
> 
> Darn.
> 
> make -j3 is gaining a tad over a hog as well, roughly the same as
> turning START_DEBIT off.


Hrmm,. could it be fair_sleeper muck placing too many tasks too far left
on wakeup starving others?