[mpich-discuss] Time distribution of Intel MPI Benchmark (PingPong)

[Klaus Philip]

Dear Antonio,
Thank you for your fast answering.
Do you know how to disable this "active polling" ?

Greetings,
Philip

Von: discuss-bounces at mpich.org [mailto:discuss-bounces at mpich.org] Im Auftrag von "Antonio J. Peña"
Gesendet: Dienstag, 1. Juli 2014 16:30
An: discuss at mpich.org
Betreff: Re: [mpich-discuss] Time distribution of Intel MPI Benchmark (PingPong)


Dear Philip,

Both functions are part of MPICH. MPICH uses intentionally active polling to minimize the latency on communications. In short, you get faster communications by repeatedly checking for communication completion during waiting times. So, that's expected.

  Antonio


On 07/01/2014 09:16 AM, Klaus Philip wrote:
Hi,
I tested mpich2 3.1.1 with the Intel MPI Benchmark, more precisely the  "PingPong"-Benchmark.
It uses the MPI_Send and MPI_Recv function to send one message from Process 1 to Process 2 and back.
While the benchmark was running, I executed the Sysprofiler (sysprof) to check the time distribution (Picture below).

My question is now, if the two marked Processes (MPID_nem_lmt_shm_progress and poll) are parts of MPICH or the Intel-PingPong-Benchmark, because they are both consuming much time (49,03% and 19,99%).

[cid:image001.jpg at 01CF95D3.3B30B680]
Greetings,
Philip




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--

Antonio J. Peña

Postdoctoral Appointee

Mathematics and Computer Science Division

Argonne National Laboratory

9700 South Cass Avenue, Bldg. 240, Of. 3148

Argonne, IL 60439-4847

apenya at mcs.anl.gov<mailto:apenya at mcs.anl.gov>

www.mcs.anl.gov/~apenya<http://www.mcs.anl.gov/~apenya>
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