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Subject: Re: [OMPI users] MPI_Comm_accept - Busy wait
From: Ralph Castain (rhc_at_[hidden])
Date: 2011-10-14 14:43:25


Sorry - been occupied. This is normal behavior. As has been discussed on this list before, OMPI made a design decision to minimize latency. This means we aggressively poll for connections. Only thing you can do is tell it to yield the processor when idle so, if something else is trying to run, we will let it get in there a little earlier. Use -mca mpi_yield_when_idle 1

However, we have seen that if no other user processes are trying to run, then the scheduler hands the processor right back to you - and you'll still see that 100% number. It doesn't mean we are being hogs - it just means that nothing else wants to run, so we happily accept the time.

On Oct 14, 2011, at 12:21 PM, Thatyene Louise Alves de Souza Ramos wrote:

> Does anyone have any idea?
>
> ---
> Thatyene Ramos
>
> On Fri, Oct 7, 2011 at 12:01 PM, Thatyene Louise Alves de Souza Ramos <thatyene_at_[hidden]> wrote:
> Hi there!
>
> In my code I use MPI_Comm_accept in a server-client communication. I noticed that the server remains on busy wait whereas waiting for clients connections, using 100% of CPU if there are no other processes running.
>
> I wonder if there is any way to prevent this from happening.
>
> Thanks in advance.
>
> Thatyene Ramos
>
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