Re: rt20 scheduling latency testcase and failure data
From: Sébastien Dugué
Date: Thu May 18 2006 - 05:53:24 EST
On Thu, 2006-05-18 at 02:38 -0700, Darren Hart wrote:
> On Thursday 18 May 2006 01:58, Sébastien Dugué wrote:
> > On Thu, 2006-05-18 at 10:47 +0200, Ingo Molnar wrote:
> > > * Sébastien Dugué <sebastien.dugue@xxxxxxxx> wrote:
> > > > Darren,
> > > >
> > > > On Mon, 2006-05-15 at 18:30 -0700, Darren Hart wrote:
> > > > > Following Ingo's example I have included the modified test case
> > > > > (please see the original mail for librt.h) that starts the trace
> > > > > before each sleep and disables it after we wake up. If we have
> > > > > missed a period, we print the trace.
> > > >
> > > > Your test program fails (at least on my box) as the overhead of
> > > > starting and stopping the trace in the 5 ms period is just too high.
> > > >
> > > > By moving the latency_trace_start() at the start of the thread
> > > > function and latency_trace_stop() at the end, everything runs fine. I
> > > > did not have any period missed even under heavy load.
> > >
> > > could you send us the fixed testcase?
> > No problem, see attachment.
> I found several similar problems in my original test case, please see my
> earlier mail from today where I included a completely rewritten test case
> with buffered output and new periodic logic.
> The case attached here seems to try to print the trace without first stopping
> it. I don't think that will result in the desired output. My new test case
> addresses that issue as well.
> I'd appreciate any feedback, thanks.
Just saw your post, testing now...
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