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Subject: Re: [OMPI devel] openib btl build question
From: Brian W. Barrett (brbarret_at_[hidden])
Date: 2008-05-22 10:48:43


Ah. On Linux, --without-threads really doesn't gain you that much. The
default glibc is still thread safe, and there are only a couple small
parts of the code that use locks (like the OOB TCP). It's generally just
easier to leave threads enabled on Linux.

Brian

On Thu, 22 May 2008, Don Kerr wrote:

> Thanks Jeff. Thanks Brian.
>
> I ran into this because I was specifically trying to configure with
> "--disable-progress-threads --disable-mpi-threads" at which point I
> figured, might as well turn off all threads so I added
> "--without-threads" as well. But can't live without mpi_leave_pinned so
> threads are back.
>
>
> Jeff Squyres wrote:
>> On May 21, 2008, at 4:37 PM, Brian W. Barrett wrote:
>>
>>
>>>> ptmalloc2 is not *required* by the openib btl. But it is required on
>>>> Linux if you want to use the mpi_leave_pinned functionality. I see
>>>> one function call to __pthread_initialize in the ptmalloc2 code -- it
>>>> *looks* like it's a function of glibc, but I don't know for sure.
>>>>
>>> There's actually more than that, it's just buried a bit. There's a
>>> whole
>>> bunch of thread-specific data stuff, which is wrapped so that
>>> different
>>> thread packages can be used (although OMPI only supports pthreads).
>>> The
>>> wrappers are in ptmalloc2/sysdeps/pthreads.
>>>
>>
>>
>> Doh! I didn't "grep -r"; my bad...
>>
>>
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