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Subject: Re: [OMPI users] Does sendrecv guarantee order?
From: Saliya Ekanayake (esaliya_at_[hidden])
Date: 2014-02-13 22:59:27


Hi George,

Thank you for your prompt reply, but my apologies for missing it and it's
been quite a while.

Anyway, to answer your question I was trying to do sendrecv in a chain
where "toSend" and "receiveFrom" ranks are not the same. I was using a
single buffer, which resulted in cases where the buffer content got
replaced with received values before being able to send its original
content. I think it was an error on my side to use a single buffer in a
pipeline sendrecev. I fixed it by having two buffers.

I guess still with MPI_IN_PLACE this could happen. Please correct me here
if I am wrong.

Thank you,
Saliya

On Wed, Nov 27, 2013 at 6:00 AM, George Bosilca <bosilca_at_[hidden]> wrote:

> Why do you need an order? If you plan to send and receive on the same
> buffer, you should use the MPI constructs for that, namely MPI_IN_PLACE.
>
> George.
>
> On Nov 27, 2013, at 07:20 , Saliya Ekanayake <esaliya_at_[hidden]> wrote:
>
> Hi,
>
> Just want to verify if sendrecv provides any guarantees as to which
> operation (send or receive) happens first. I think it is not, is it?
>
> Thank you,
> Saliya
>
> --
> Saliya Ekanayake esaliya_at_[hidden]
> Cell 812-391-4914 Home 812-961-6383
> http://saliya.org
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-- 
Saliya Ekanayake esaliya_at_[hidden]
Cell 812-391-4914 Home 812-961-6383
http://saliya.org