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[Bug libgomp/37586] OpenMP thinks that I have 1 processor on an 8 processor pc
- From: "rrpeter at sandia dot gov" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 19 Sep 2008 22:01:11 -0000
- Subject: [Bug libgomp/37586] OpenMP thinks that I have 1 processor on an 8 processor pc
- References: <bug-37586-4376@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #4 from rrpeter at sandia dot gov 2008-09-19 22:01 -------
Subject: Re: OpenMP thinks that I have 1 processor
on an 8 processor pc
jakub at gcc dot gnu dot org wrote:
> ------- Comment #3 from jakub at gcc dot gnu dot org 2008-09-19 21:45 -------
> As already said in the openmp.org forum, omp_get_num_procs () will only return
> smaller number than the number of system CPUs online, if GOMP_CPU_AFFINITY env
> var is used, or if the calling process and/or thread has CPU affinity limited
> to a subset of CPUs. You can just step through omp_get_num_procs () /
> get_num_procs () routine and/or look at strace to see what is the case.
>
> omp_get_max_threads () in 4.3 and earlier incorrectly adjusts for dyn_var etc.,
> works like parallel region determines the number of threads if num_thread isn't
> specified, only on the GCC trunk (4.4 and later) it returns the nthreads_var
> ICV.
>
>
> --
>
> jakub at gcc dot gnu dot org changed:
>
> What |Removed |Added
> ----------------------------------------------------------------------------
> Status|RESOLVED |UNCONFIRMED
> Keywords| |openmp
> Resolution|INVALID |
>
>
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37586
>
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> You reported the bug, or are watching the reporter.
>
>
Hi,
Do you mean that there might be a problem with gcc 4.3 with regards to
the problem that I see, but it may be fixed with gcc 4.4?
It appears to me that GOMP_CPU_AFFINITY allows you to force threads onto
particular processors -- is this correct? So are you suggesting that I
could use GOMP_CPU_AFFINITY to sidestep this problem? If so, I will try
it Monday.
Thanks! Have a nice weekend!
Ralph
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37586