Thank you for your suggestion.
I have more information and possible explanation, and more questions.
It looks like that NUMA plays a big role here.
In summary, it looks like that synchronization overhead of MPI file I/O
among "socket" is a lot higher than the overhead among the processes within
a s
On Mon, 2020-04-06 at 10:02 -0400, Dong-In Kang via users wrote:
>
> Thank you Edgar for the information.
>
> I also tried MPI_File_write_at_all(), but it usually makes the
> performance worse.
> My program is very simple.
> Each MPI process writes a consecutive portion of a file.
> No interleavi
t the important distinction!
>
> Thanks,
> Collin
>
>
>
> **From:** users **On Behalf Of **Gilles
> GOUAILLARDET via users
> **Sent:** Monday, April 6, 2020 11:01 AM
> **To:** Open MPI Users
> **Cc:** Gilles GOUAILLARDET
> **Subject:** Re: [OMPI user
users
Sent: Monday, April 6, 2020 11:01 AM
To: Open MPI Users
Cc: Gilles GOUAILLARDET
Subject: Re: [OMPI users] Slow collective MPI File IO
Collin,
Do you have any data to backup your claim?
As long as MPI-IO is used to perform file I/O, the Fortran bindings overhead
should be hardly noticeable
h
>> achieved in this scenario, as long as the number of processes are moderate.
>>
>>
>>
>> Thanks
>>
>> Edgar
>>
>>
>>
>> From: Dong-In Kang
>> Sent: Monday, April 6, 2020 9:34 AM
>> To: Collin Strassb
AM
To: Gabriel, Edgar
Cc: Dong-In Kang ; Open MPI Users
Subject: Re: [OMPI users] Slow collective MPI File IO
Thank you Edgar for the information.
I also tried MPI_File_write_at_all(), but it usually makes the performance
worse.
My program is very simple.
Each MPI process writes a
t;
>
>
> *From:* Dong-In Kang
> *Sent:* Monday, April 6, 2020 9:34 AM
> *To:* Collin Strassburger
> *Cc:* Open MPI Users ; Gabriel, Edgar <
> egabr...@central.uh.edu>
> *Subject:* Re: [OMPI users] Slow collective MPI File IO
>
>
>
> Hi Collin,
>
>
&g
achieved in this
scenario, as long as the number of processes are moderate.
Thanks
Edgar
From: Dong-In Kang
Sent: Monday, April 6, 2020 9:34 AM
To: Collin Strassburger
Cc: Open MPI Users ; Gabriel, Edgar
Subject: Re: [OMPI users] Slow collective MPI File IO
Hi Collin,
It is written in C.
So, I
2 AM
> *To:* Gabriel, Edgar
> *Cc:* Dong-In Kang ; Open MPI Users <
> users@lists.open-mpi.org>
> *Subject:* Re: [OMPI users] Slow collective MPI File IO
>
>
>
>
>
> Thank you Edgar for the information.
>
>
>
> I also tried MPI_File_write_at_all()
users
Sent: Monday, April 6, 2020 10:02 AM
To: Gabriel, Edgar
Cc: Dong-In Kang ; Open MPI Users
Subject: Re: [OMPI users] Slow collective MPI File IO
Thank you Edgar for the information.
I also tried MPI_File_write_at_all(), but it usually makes the performance
worse.
My program is very
u some pointers on where to start to look.
>
> Thanks
>
> Edgar
>
>
>
> *From:* users *On Behalf Of *Dong-In
> Kang via users
> *Sent:* Monday, April 6, 2020 7:14 AM
> *To:* users@lists.open-mpi.org
> *Cc:* Dong-In Kang
> *Subject:* [OMPI users] Slow collect
on where to start to look.
Thanks
Edgar
From: users On Behalf Of Dong-In Kang via
users
Sent: Monday, April 6, 2020 7:14 AM
To: users@lists.open-mpi.org
Cc: Dong-In Kang
Subject: [OMPI users] Slow collective MPI File IO
Hi,
I am running an MPI program where N processes write to a single file
Hi,
I am running an MPI program where N processes write to a single file on a
single shared memory machine.
I’m using OpenMPI v.4.0.2.
Each MPI process write a 1MB chunk of data for 1K times sequentially.
There is no overlap in the file between any of the two MPI processes.
I ran the program
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