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Subject: Re: [patch] Re: PostgreSQL pgbench performance regression in
	2.6.23+
From: Mike Galbraith <efault@gmx.de>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@elte.hu>, Greg Smith <gsmith@gregsmith.com>,
       Dhaval Giani <dhaval@linux.vnet.ibm.com>,
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On Sat, 2008-06-07 at 15:07 +0200, Peter Zijlstra wrote:
> On Sat, 2008-06-07 at 14:50 +0200, Mike Galbraith wrote:
> > Since I tested mysql+oltp and made the dang pdf of the results, I may
> > as well actually attach the thing <does that before continuing...>.
> > 
> > BTW, I have a question wrt avg_overlap.  When a wakeup cause the current
> > task to begin sharing CPU with a freshly awakened task, the current task
> > is tagged.. but the wakee isn't.  How come?  If one is sharing, so is
> > the other.
> 
> avg_overlap is about measuring how long we'll run after waking someone
> else. The other measure, how long our waker shares the cpu with us,
> hasn't proven to be relevant so far.

Yeah wrt relevance, I've been playing with making it mean this and that,
with approx 0 success ;-)  If it's a measure of how long we run after
waking though, don't we need to make sure it's not a cross CPU wakeup?

	-Mike

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