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Date: Mon, 27 Aug 2001 13:04:16 +0200 (MEST)
From: Carsten Thorenz <XZ550S AT gmx DOT de>
To: cygwin AT cygwin DOT com
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Subject: Profiling with GPROF considered buggy?
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Hi!

Recently I ran into problems profiling a scientific numerical program
using Cygwin. I've seen in the list that other people had similar problems,
but no clue was found.

About my problems: I've compiled and linked the whole program with -pg,
ran it and used gprof to to print the profile. Now about the strange things:

The cumulative runtime in the "flat profile" is _way_ to small. The example
I've used is running approximately 3 minutes, but only 15 seconds are
recorded in the profile. The program doesn't do much communication
with the outside world, it only crunches numbers during those 3 minutes.
Furthermore, the functions that  I _know_ about using a lot of CPU-time
are not even listed in the flat profile.

The profiling works very fine with gcc on Linux and on OS/2, but
it doesn't work for WinNT4. I've tried it with both Cygwin and
Mingw, the problems are the same. So I guess it is not the external
library that causes the problems, but the timing routines within gcc.

My first guess: Are the timer intervals of the profiling to long, so
that it doesn't "catch" functions which are executed very fast, but
very often?

Bye, Carsten


  

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