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Subject: Re: 2.6.17-rc6-rt1
From: Mike Galbraith <efault@gmx.de>
To: Daniel Walker <dwalker@mvista.com>
Cc: tglx@linutronix.de,
       =?ISO-8859-1?Q?S=E9bastien_Dugu=E9?= <sebastien.dugue@bull.net>,
       Ingo Molnar <mingo@elte.hu>, linux-kernel@vger.kernel.org,
       John Stultz <johnstul@us.ibm.com>, Deepak Saxena <dsaxena@plexity.net>
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Date: Fri, 09 Jun 2006 20:41:06 +0200
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On Fri, 2006-06-09 at 08:55 -0700, Daniel Walker wrote:
> On Fri, 2006-06-09 at 15:42 +0200, Mike Galbraith wrote:
> > On Fri, 2006-06-09 at 15:11 +0200, Thomas Gleixner wrote:
> > > On Fri, 2006-06-09 at 14:57 +0200, Sébastien Dugué wrote:
> > > > All the round trips under strace are in the 2ms range.
> > > > 
> > > >   How on earth can it be that stracing the ping gives better
> > > > performance???
> > > 
> > > Was busy fixing a scheduling while atomic bug. I just verified that I
> > > have the same weird behaviour. I'm looking into it.
> > 
> > I downloaded and patched a ping.c to do a user triggered latency trace
> > around recvfrom() of a ping -c 1 127.0.0.1 running SCHED_RR.  We
> > schedule away at 25us, do aaaall kinds of interesting stuff, and come
> > back at 42234us.  If you want the trace, holler.  It's 51k bzipped.
> 
> What priority ?

Bare minimum.  None of the other tasks that were scheduled were rt in
their own right though.

	-Mike