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[Bug c++/53292] multi-threaded (OpenMP) is slower than single-threaded
- From: "fh_p at hotmail dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Wed, 09 May 2012 10:16:52 +0000
- Subject: [Bug c++/53292] multi-threaded (OpenMP) is slower than single-threaded
- Auto-submitted: auto-generated
- References: <bug-53292-4@http.gcc.gnu.org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53292
--- Comment #2 from FH <fh_p at hotmail dot com> 2012-05-09 10:16:52 UTC ---
I have just tested on another computer (CPU : Xeon5650 12 cores + OS :
Scientific Linux) => I reproduce the unexpected behavior (OpenMP slower than
single-threaded).
So, I believe the problem is "rather" related to gcc (than to the OS)
When I use more threads (export OMP_NUM_THREADS=2, then 6, then 12), OpenMP is
"more slower" than single-threaded. (behavior related to thread initialisation
?)