[mpich-discuss] Using MPICH2 with shared memeory

[Dai-Hee Kim]

it is really helpful
Thank you so much..

On Tue, Apr 13, 2010 at 10:28 AM, Darius Buntinas <buntinas at mcs.anl.gov>wrote:

>
> Socket connections are created for process management (between the mpiexec
> process and MPD processes and between the MPD processes and the MPI
> processes).  However communication between the MPI processes will use shared
> memory.  We don't use sysv shared memory because of the limits on the number
> and size of segments.  Instead we create temporary files and mmap them.
>
> You should, however, see a significant difference in performance on a
> multicore machine.  Try a latency benchmark (e.g., osu_latency from the OMB:
> http://mvapich.cse.ohio-state.edu/benchmarks ).  Using nemesis, you can
> force all communication to go through the network by setting the
> MPICH_NO_LOCAL environment variable for comparison:
>
> For shared memory performance:
>    mpiexec -n 2 osu_latency
> For sockets performance:
>    MPICH_NO_LOCAL=1 mpiexec -n 2 osu_latency
>
> Here's a website on tips for measuring shared memory latency:
> http://wiki.mcs.anl.gov/mpich2/index.php/Measuring_Nemesis_Performance
>
> -d
>
>
>
> On 04/13/2010 06:25 AM, Dai-Hee Kim wrote:
>
>>  Hello, everyone
>> I am testing MPICH2 on 24 cores SMP machine.
>> And, I installed MPICH2 with three devices (nemesis, ssm,
>> shm) separately and run parallel program with each device.
>> However, it seems that no device was using shared memory when I checked
>> the performance
>> and network status using netstat command (a lot of sockets created for
>> self connection)
>> Of course, I could not see any shared memory segments through ipcs -m
>> and free commands
>> I compiled MPICH2 with three devices by below configuration options
>> respectively
>> ./configure --prefix=.../nemesis --enable-fast=03
>> --with-device=ch3:nemesis
>> ./configure --prefix=.../ssm       --enable-fast=03 --with-device=ch3:ssm
>> ./configure --prefix=.../shm --enable-fast=03 --with-device=ch3:shm
>> and complied and run the parallel program using scripts (mpif90 and
>> mpiexec) in different prefix directory depending on which device I used
>> for testing.
>> Do I need to put some another options for installing MPICH2 or running
>> the parallel program with shared memory?
>> Is there anything I missed?
>> I really appreciate for your concern.
>> Thank you.
>>
>>
>>
>> _______________________________________________
>> mpich-discuss mailing list
>> mpich-discuss at mcs.anl.gov
>> https://lists.mcs.anl.gov/mailman/listinfo/mpich-discuss
>>
>
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