[mpich-discuss] Controlling MPICH busy-wait behavior

[Jeff Hammond]

You might be able to implement this across the board using
https://github.com/LLNL/wrap and interposing all calls to MPI_Wait
transparently rather than changing the application code.

Jeff

On Thu, Jun 4, 2020 at 8:30 AM Mccall, Kurt E. (MSFC-EV41) via discuss <
discuss at mpich.org> wrote:

> Thanks Hui.  I will use MPI_Iprobe + MPI_Test.
>
>
>
> Kurt
>
>
>
> *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>
> *Reply-To: *"discuss at mpich.org" <discuss at mpich.org>
> *Date: *Wednesday, June 3, 2020 at 3:57 PM
> *To: *"discuss at mpich.org" <discuss at mpich.org>
> *Cc: *"Mccall, Kurt E. (MSFC-EV41)" <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.
>
>
>
>
> https://stackoverflow.com/questions/14560714/probe-seems-to-consume-the-cpu/14562840#14562840
> <https://urldefense.proofpoint.com/v2/url?u=https-3A__stackoverflow.com_questions_14560714_probe-2Dseems-2Dto-2Dconsume-2Dthe-2Dcpu_14562840-2314562840&d=DwMGaQ&c=ApwzowJNAKKw3xye91w7BE1XMRKi2LN9kiMk5Csz9Zk&r=6cP1IfXu3IZOHSDh_vBqciYiIh4uuVgs1MSi5K7l5fQ&m=stZqd9Fs3P0zmm4350zML37qvC5jT4e9jhayHaxrcbw&s=auPT9hTHN3AOIqD0_f-gKxki1W12bFbMF-6s6AGIL_w&e=>
>
>
>
>
>
> Thanks,
>
> Kurt
>
>
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-- 
Jeff Hammond
jeff.science at gmail.com
http://jeffhammond.github.io/
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