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Date: Wed, 1 Dec 2004 11:32:51 +0100
From: Ingo Molnar <mingo@elte.hu>
To: Rui Nuno Capela <rncbc@rncbc.org>
Cc: linux-kernel@vger.kernel.org, Lee Revell <rlrevell@joe-job.com>,
       mark_h_johnson@raytheon.com, "K.R. Foley" <kr@cybsft.com>,
       Bill Huey <bhuey@lnxw.com>, Adam Heath <doogie@debian.org>,
       Florian Schmidt <mista.tapas@gmx.net>,
       Thomas Gleixner <tglx@linutronix.de>,
       Michal Schmidt <xschmi00@stud.feec.vutbr.cz>,
       Fernando Pablo Lopez-Lezcano <nando@ccrma.stanford.edu>,
       Karsten Wiese <annabellesgarden@yahoo.de>,
       Gunther Persoons <gunther_persoons@spymac.com>, emann@mrv.com,
       Shane Shrybman <shrybman@aei.ca>, Amit Shah <amit.shah@codito.com>,
       Esben Nielsen <simlo@phys.au.dk>
Subject: Re: Real-Time Preemption, -RT-2.6.10-rc2-mm3-V0.7.31-7
Message-ID: <20041201103251.GA18838@elte.hu>
References: <36536.195.245.190.93.1101471176.squirrel@195.245.190.93> <20041129111634.GB10123@elte.hu> <41358.195.245.190.93.1101734020.squirrel@195.245.190.93> <20041129143316.GA3746@elte.hu> <20041129152344.GA9938@elte.hu> <48590.195.245.190.94.1101810584.squirrel@195.245.190.94> <20041130131956.GA23451@elte.hu> <17532.195.245.190.94.1101829198.squirrel@195.245.190.94>
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* Rui Nuno Capela <rncbc@rncbc.org> wrote:

> > 		if (!(count++ & 1))
> > 			gettimeofday(0,1);
> > 	}

> Done that.
> 
> New XRUN traces are attached, while running RT-V0.7.31-15 now.
> However, I don't seem to get any notorious difference on the results,
> since previous ones. All latencies traced ca. 26-27 usecs.

ah, found the reason why the trace length didnt improve:

+               {       // Trigger off trace every other poll...
+                       static unsigned int xruntrace_count = 0;
+                       if ((xruntrace_count++ % 1) == 0)
+                               gettimeofday(0,1);
+               }

this should either be '& 1' as i originally suggested, or '% 2'. The way 
it is right now it will stop the trace every time - i.e. what we had 
before.

so please disregard my freerunning suggestionsand try the two-periods
solution first.

	Ingo