I have additional question about the internal progress of these non-blocking routines. I have simple test case: err = MPI_File_iwrite_all( fh, buf, bufsize, MPI_INT, &req); MPI_Wait(&req, &status); Here MPI_File_iwrite_all returns immediately and profiling shows time spent in MPI_Wait. Next, I modified example to overlap i/o with some computations: some_compute_fun() { .....some_flops_here...... } err = MPI_File_iwrite_all( fh, buf, bufsize, MPI_INT, &req); some_compute_fun(); MPI_Wait(&req, &status); In this case I still see the similar time spent in MPI_Wait. I added MPI_Test for the non-blocking request as: some_compute_fun() { MPI_Test(&req, &flag, &status); .....some_flops_here...... } err = MPI_File_iwrite_all( fh, buf, bufsize, MPI_INT, &req); some_compute_fun(); MPI_Wait(&req, &status); Now I see that i/o operation progresses in background and don't see any time spent in MPI_Wait. Few months ago I was testing non-blocking collective operations in mvapich and saw similar behaviour where I have to use few MPI_Test calls to make progress with non-blocking collectives (this will be addressed in upcoming releases). I am testing above i/o example on my laptop and haven't tested other non-blocking collectives. Before analysing/profiling this further on production cluster / bg-q, I would like to know: - what is the expected behaviour? - are there any specific options that I have to use to make sure internal progress? -Pramod p.s. I just built mpich-3.2 with configure,make,make install on OS X, without looking into all configure options... On Tue, Feb 9, 2016 at 3:51 AM, Rob Latham <[email protected]> wrote:

On 02/08/2016 06:04 PM, pramod kumbhar wrote:

...

thanks! MPI_File_iwrite_all working as expected.

I'm always glad to see folks looking at the MPI-IO routines. Let us know how your research progresses.

==rob

...

-Pramod

On Tue, Feb 9, 2016 at 12:52 AM, Balaji, Pavan <[email protected] <mailto:[email protected]>> wrote:

I believe it is valid to do that in split collectives. If you want truly nonblocking nature, the standard way to do it would be to use nonblocking collective I/O, i.e., MPI_File_iwrite_all. This is guaranteed to not block during the MPI_File_iwrite_all call.

-- Pavan

> On Feb 8, 2016, at 5:48 PM, pramod kumbhar <[email protected] <mailto:[email protected]>> wrote: > > Hello All, > > I am testing MPI_FIle_write_all_begin/_end and it seems like > MPI_File_write_all_begin waits for i/o completion. > > Could someone confirm the implementation of these routines? > > Thanks, > Pramod > _______________________________________________ > discuss mailing list [email protected] <mailto:[email protected]> > To manage subscription options or unsubscribe: > https://lists.mpich.org/mailman/listinfo/discuss

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