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Subject: Re: [OMPI users] Mimicking timeout for MPI_Wait
From: Katz, Jacob (jacob.katz_at_[hidden])
Date: 2009-12-06 07:29:01


Thanks.
Yes, I meant in the question that I was looking for something creative, both fast responding and not using 100% CPU all the time.
I guess I’m not the first one to face this question. Have anyone done anything “better” than the simple solution?
--------------------------------
Jacob M. Katz | jacob.katz_at_[hidden]<mailto:jacob.katz_at_[hidden]> | Work: +972-4-865-5726 | iNet: (8)-465-5726

From: users-bounces_at_[hidden] [mailto:users-bounces_at_[hidden]] On Behalf Of Richard Treumann
Sent: Friday, December 04, 2009 22:03
To: Open MPI Users
Subject: Re: [OMPI users] Mimicking timeout for MPI_Wait


If you are hoping for a return on timeout, almost zero CPU use while waiting and fast response you will need to be pretty creative. Here is a simple solution that may be OK if you do not need both fast response and low CPU load.

flag = false;
for ( ; ! is_time_up(); )
MPI_Test( ........ &flag, ......);
if (flag) break;
usleep(..)
}

Make the sleep short or leave it out and you hog CPU, make it long and your lag time for detecting a message that arrives after you enter the loop will average 1/2 the sleep plus a bit.



Dick Treumann - MPI Team
IBM Systems & Technology Group
Dept X2ZA / MS P963 -- 2455 South Road -- Poughkeepsie, NY 12601
Tele (845) 433-7846 Fax (845) 433-8363


users-bounces_at_[hidden] wrote on 12/04/2009 01:38:05 PM:

> [image removed]
>
> Re: [OMPI users] Mimicking timeout for MPI_Wait
>
> Jeff Squyres
>
> to:
>
> Open MPI Users
>
> 12/04/2009 01:38 PM
>
> Sent by:
>
> users-bounces_at_[hidden]
>
> Please respond to Open MPI Users
>
> On Dec 3, 2009, at 3:31 AM, Katz, Jacob wrote:
>
> > I wonder if there is a BKM (efficient and portable) to mimic a
> timeout with a call to MPI_Wait, i.e. to interrupt it once a given
> time period has passed if it hasn’t returned by then yet.
>
> Pardon my ignorance, but what does BKM stand for?
>
> Open MPI does not currently implement a timeout-capable MPI_WAIT.
> Such functionality probably could be implemented (e.g., in the MPIX
> "experimental" namespace), especially since Open MPI polls for
> progress -- it could check a timer every so often while polling --
> but no one has done so.
>
> --
> Jeff Squyres
> jsquyres_at_[hidden]
>
>
> _______________________________________________
> users mailing list
> users_at_[hidden]
> http://www.open-mpi.org/mailman/listinfo.cgi/users
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