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What kind of data is collected with -fprofile-generate?
- From: Clemens Eisserer <linuxhippy at gmail dot com>
- To: gcc-help at gcc dot gnu dot org
- Date: Fri, 24 Jul 2009 09:46:14 -0400
- Subject: What kind of data is collected with -fprofile-generate?
Hi,
I've been playing with profile driven optimizations lately and it
seems to work really well :)
Even with -mtune=generic I am able to get a 20% time reduction for a
critical piece of code.
What I wonder however is, how the profiling informations are collected.
E.g. when profiling pixman, I feed about 1Mio trapezoids to it,
however gcc only collects ~1.5kb profile information for that Object
file:
> -rw-rw-r-- 1 ce ce 1784 2009-07-24 15:22 libpixman_1_la-pixman-trap.gcda
It seems irrelevant how much test-data I feed duing the profiling
stage, it won't grow beyond that 1.7kb.
Any ideas why?
Thank you in advance, Clemens Eisserer