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Date: Sun, 05 Jan 2003 12:38:16 -0800
From: Andrew Morton <akpm@digeo.com>
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To: uaca@alumni.uv.es
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Subject: Re: 2.5.54-mm3
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uaca@alumni.uv.es wrote:
> 
> On Sat, Jan 04, 2003 at 01:00:38AM -0800, Andrew Morton wrote:
> >
> > http://www.zip.com.au/~akpm/linux/patches/2.5/2.5.54/2.5.54-mm3/
> 
> It seems to me that the patch you pointed here doesn't include the latency
> instrumentation.

No, it doesn't.  You can monitor the latency using realfeel or realfeel2
from http://www.zip.com.au/~akpm/linux/amlat.tar.gz

But that won't tell you _why_ large latencies are occurring.   For that,
you'll need to apply
http://www.zip.com.au/~akpm/linux/patches/2.5/2.5.54/2.5.54-mm3/experimental/rtc-debug.patch
and run `amlat'.  This combination will spit out stack backtraces whenever
there is a 2 millisecond scheduling overrun.

> Where it is the needed instrumentation to meassure it?
> 
> In http://www.zip.com.au/~akpm/linux/ the are no timepeg/intlat patches for
> 2.5...

That's not suitable for this work.  intlat is OK for locating and
measuring interrupts-off code paths.   But it's a bit hard to drive.
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