[mpich-discuss] MPI_THREAD_MULTIPLE

[Bobby Philip]

Jeff:

Thanks for your response. It is indeed a Cray system that I am working
with. I'll try your suggestion of MPI_THREAD_SERIALIZED to see whether
there is a difference and get back to you. I am already aggregating
communication. Do you guys have any configure scripts tuned for Cray
systems if I needed to install the latest mpich?

Thanks!
Bobby


On Tue, Jul 2, 2013 at 2:41 AM, Jeff Hammond <jeff.science at gmail.com> wrote:

> I have done my own studies of this but only in detail on Blue Gene/Q,
> which supports both fine-grain and fat locking to support
> MPI_THREAD_MULTIPLE.
>
> I believe that CrayMPI takes a noticeable hit in MPI_THREAD_MULTIPLE
> because their network hardware is very low latency and the software
> overhead associated with locking (which is fat in their case AFAIK) is
> noticeable by comparison.  Is that the vendor in question?
>
> Do you have the option to aggregate communication and or otherwise use
> MPI_THREAD_SERIALIZED instead?  If not, then there really isn't an
> alternative so comparative study will only make you a sad panda.
> However, if you can use MPI_THREAD_SERIALIZED, perhaps with some
> overhead, then you can compare the two implementations.
>
> It would be helpful if you could share code and system details.
>
> Best,
>
> Jeff
>
> On Mon, Jul 1, 2013 at 2:05 AM, Bobby Philip
> <bphilip.kondekeril at gmail.com> wrote:
> > Hi:
> >
> > Are there any studies that have been done on the effect of turning on
> > MPI_THREAD_MULTIPLE with the latest versions of MPICH? I have an AMR
> > application where halo or ghost updates require lots of small messages
> to be
> > sent/rec'd and I am currently seeing a performance hit with a vendor
> > specific implementation based on MPICH2 and am trying to see whether
> there
> > are any implementations out there that might deliver better performance.
> >
> > Thanks,
> > Bobby
> >
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>
> --
> Jeff Hammond
> jeff.science at gmail.com
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