[petsc-users] Update of the buffer

[Junchao Zhang]

On Thu, Feb 10, 2022 at 8:17 AM Medane TCHAKOROM <
medane.tchakorom at univ-fcomte.fr> wrote:

> Hello ,
>
> Sorry if this question does not belong to this mailling list, i'am using
> Petsc , but with some
>
> MPI parts code, when dealing with communication.
>
> If a make two consecutive MPI_Isend requests, and if the destination
> processor has not yet receive the message inbetween the two calls, will the
> buffer be updated ? I mean if I send message "1" for the first request,
> then send "0" as the second message. Will the receiver receive "0" as
> message ? I not, how can I do to update the message ?
>
If you mean send buffer,  you need MPI_Wait() to reuse the send buffer, i.e,

MPI_Isend(sbuf, .., &req);
MPI_Wait(&req,MPI_STATUS_IGNORE);
refill sbuf
MPI_Isend(sbuf, .., &req);


> Thanks
>
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