[vdr] How to speed up vdr start ?

Marko Mäkelä marko.makela at hut.fi
Tue Aug 9 21:04:49 CEST 2005


On Tue, Aug 09, 2005 at 07:00:24PM +0200, Christoph Hermanns wrote:
> >>When i run the runvdr script manually, it took also a few seconds before
> >>the picture is shown on tv. Can this startup be speeded up ?
> >>Any hints are welcome.
> >
> >Use OProfile to identify the bottlenecks in vdr startup.
> 
> 
>  What is OProfile ? Is it part of any standard gcc package ?
>  From where can I get OProfile ?

OProfile <http://oprofile.sourceforge.net/> is a continuous profiler
that is independent of any compiler.  It merely produces more readable
output if you compile the code with gcc -g.  No compile-time, link-time
or run-time instrumentation is needed, as is the case with gprof,
efence and valgrind, respectively.  Instead, OProfile makes use of the
performance counters embedded in any modern processor (I guess Pentium
and later).  The performance penalty depends on the accuracy requested,
but typically it is a few percent only.  The tool is comparable to DEC
(then Compaq then HP) DCPI and Intel VTune.

I've used OProfile on Intel Celeron, Intel Pentium M and AMD Opteron,
maybe even the AMD K6-2, on 2.4 and 2.6 series kernels.  Be sure to
enable the local APIC, or otherwise the NMI based performance counter
interrupts won't be available.  On my vdr box, I have tuned the
softdevice plugin based on OProfile measurements.

Generally, for measuring start-up bottlenecks, I think you'd better
use bootchart.  I haven't tried it, since apparently it hasn't been
packaged for Debian GNU/Linux.

	Marko



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