[mpich-discuss] Controlling MPICH busy-wait behavior

Mccall, Kurt E. (MSFC-EV41) kurt.e.mccall at nasa.gov
Thu Jun 4 10:30:02 CDT 2020

Thanks Hui.  I will use MPI_Iprobe + MPI_Test.


From: Zhou, Hui <zhouh at anl.gov>
Sent: Thursday, June 4, 2020 10:27 AM
To: discuss at mpich.org
Cc: Mccall, Kurt E. (MSFC-EV41) <kurt.e.mccall at nasa.gov>
Subject: [EXTERNAL] Re: [mpich-discuss] Controlling MPICH busy-wait behavior

There is no such option for MPICH. If you configure with ch3:sock, which waits for the progress with blocking `poll`, I think it will not hog the CPU by default, for other configurations, it always busy waits.

Is using MPI_Iprobe + MPI_Test an option for you? If your process can afford latency, then you can control your own sleep cycles between MPI_Test. If MPICH will implement such non-busy-wait option, internally it will just do the same test-sleep cycles.

Hui Zhou

From: "Mccall, Kurt E. (MSFC-EV41) via discuss" <discuss at mpich.org<mailto:discuss at mpich.org>>
Reply-To: "discuss at mpich.org<mailto:discuss at mpich.org>" <discuss at mpich.org<mailto:discuss at mpich.org>>
Date: Wednesday, June 3, 2020 at 3:57 PM
To: "discuss at mpich.org<mailto:discuss at mpich.org>" <discuss at mpich.org<mailto:discuss at mpich.org>>
Cc: "Mccall, Kurt E. (MSFC-EV41)" <kurt.e.mccall at nasa.gov<mailto:kurt.e.mccall at nasa.gov>>
Subject: [mpich-discuss] Controlling MPICH busy-wait behavior

Is there a means to tell MPICH to yield to other processes when performing a busy-wait for incoming messages?   The page below distinguishes between “aggressive busy-wait” and “degraded busy-wait”, where the latter is what I’d like to try.



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