- mpiwg-p2p - mailman3.cels.anl.gov

Re: [mpiwg-p2p] Ordering of P2P messages in multithreaded applications
by Jeff Hammond 15 Nov '18

15 Nov '18

A send of 0 must be issued by one of the two threads before buffer turns to 1. Messages must match in order at receiver and that will lead to “0\n1\n” being printed at the target. Jeff Sent from my iPhone > On Nov 15, 2018, at 4:16 AM, Joachim Protze via mpiwg-p2p <mpiwg-p2p(a)lists.mpi-forum.org> wrote: > > Hi all, > > I have a question on the "Semantics of Point-to-Point Communication" in a multithreaded context. > > For me the situation for the code below is not clear, especially with respect to the paragraph in MPI-3.1 p.41, l.10-17 : > > > void test(int rank) { > int msg = 0; > if (rank == 0) { > #pragma omp parallel num_threads(2) > #pragma omp critical > { > MPI_Send(&msg, 1, MPI_INT, 1, 42, MPI_COMM_WORLD); > msg++; > } > } else if (rank == 1) { > MPI_Recv(&msg, 1, MPI_INT, 0, 42, MPI_COMM_WORLD, MPI_STATUS_IGNORE); > printf("Received %i\n", msg); > MPI_Recv(&msg, 1, MPI_INT, 0, 42, MPI_COMM_WORLD, MPI_STATUS_IGNORE); > printf("Received %i\n", msg); > } > } > > Two threads on the first process send a message, the first thread sends 0, the second thread send 1. From OpenMP semantics, the first send happens before the second send. > > Is there a guarantee, that the other process receives the 0 first? > > Thanks, > Joachim > > > -- > Dipl.-Inf. Joachim Protze > > IT Center > Group: High Performance Computing > Division: Computational Science and Engineering > RWTH Aachen University > Seffenter Weg 23 > D 52074 Aachen (Germany) > Tel: +49 241 80- 24765 > Fax: +49 241 80-624765 > protze(a)itc.rwth-aachen.de > www.itc.rwth-aachen.de >

1 0

Ordering of P2P messages in multithreaded applications
by Joachim Protze 15 Nov '18

15 Nov '18

Hi all, I have a question on the "Semantics of Point-to-Point Communication" in a multithreaded context. For me the situation for the code below is not clear, especially with respect to the paragraph in MPI-3.1 p.41, l.10-17 : void test(int rank) { int msg = 0; if (rank == 0) { #pragma omp parallel num_threads(2) #pragma omp critical { MPI_Send(&msg, 1, MPI_INT, 1, 42, MPI_COMM_WORLD); msg++; } } else if (rank == 1) { MPI_Recv(&msg, 1, MPI_INT, 0, 42, MPI_COMM_WORLD, MPI_STATUS_IGNORE); printf("Received %i\n", msg); MPI_Recv(&msg, 1, MPI_INT, 0, 42, MPI_COMM_WORLD, MPI_STATUS_IGNORE); printf("Received %i\n", msg); } } Two threads on the first process send a message, the first thread sends 0, the second thread send 1. From OpenMP semantics, the first send happens before the second send. Is there a guarantee, that the other process receives the 0 first? Thanks, Joachim -- Dipl.-Inf. Joachim Protze IT Center Group: High Performance Computing Division: Computational Science and Engineering RWTH Aachen University Seffenter Weg 23 D 52074 Aachen (Germany) Tel: +49 241 80- 24765 Fax: +49 241 80-624765 protze(a)itc.rwth-aachen.de www.itc.rwth-aachen.de

1 0

Re: [mpiwg-p2p] FP16 at MPI Forum in Dec 2017
by Atsushi HORI 14 Nov '17

14 Nov '17

Hi, Dan, > 2017/11/14 10:26、HOLMES Daniel <d.holmes(a)epcc.ed.ac.uk> wrote; > > I’m going to present the attach slide at the MPI BoF on Wednesday at SC17. > > If you have comments/suggestions/changes, please let me know by lunch tomorrow. The slides look good. Thanks. ----- Atsushi HORI ahori(a)riken.jp http://aics-sys.riken.jp

1 0

Re: [mpiwg-p2p] FP16 at MPI Forum in Dec 2017
by HOLMES Daniel 13 Nov '17

13 Nov '17

Excellent idea - thanks Jeff. Cheers, Dan. On 13 Nov 2017, at 18:30, Jeff Hammond <jeff.science(a)gmail.com<mailto:[email protected]>> wrote: Please link to GitHub ticket, which has good background. Sent from my iPhone On Nov 13, 2017, at 5:26 PM, HOLMES Daniel <d.holmes(a)epcc.ed.ac.uk<mailto:[email protected]>> wrote: Hi all, I’m going to present the attach slide at the MPI BoF on Wednesday at SC17. If you have comments/suggestions/changes, please let me know by lunch tomorrow. Cheers, Dan. On 13 Nov 2017, at 14:10, Anthony Skjellum <tony(a)runtimecomputing.com<mailto:[email protected]>> wrote: I prefer #2. Tony On Mon, Nov 13, 2017 at 12:47 PM, HOLMES Daniel <d.holmes(a)epcc.ed.ac.uk<mailto:[email protected]>> wrote: Hi all, I need to let Martin know what this WG needs in terms of agenda items. Will the FP16 proposal be ready for a formal reading at the Dec meeting? I suspect not, because there are still changes being made to the text for a variety of reasons. The announcement deadline for readings is rapidly approaching (7 days from now). Please vote for one of these options: 1) Formal reading of FP16 proposal 2) Plenary presentation of current status of FP16 and outstanding questions/issues 3) No presentation to the whole Forum In addition, do we want WG time to progress this proposal? Cheers, Dan. -- The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336. _______________________________________________ mpiwg-p2p mailing list mpiwg-p2p(a)lists.mpi-forum.org<mailto:[email protected]> https://lists.mpi-forum.org/mailman/listinfo/mpiwg-p2p -- Tony Skjellum, PhD RunTime Computing Solutions, LLC tony(a)runtimecomputing.com<mailto:[email protected]> direct: +1-205-918-7514 cell: +1-205-807-4968 _______________________________________________ mpiwg-p2p mailing list mpiwg-p2p(a)lists.mpi-forum.org<mailto:[email protected]> https://lists.mpi-forum.org/mailman/listinfo/mpiwg-p2p <MPI BoF - Point-to-Point.pptx> The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336. _______________________________________________ mpiwg-p2p mailing list mpiwg-p2p(a)lists.mpi-forum.org<mailto:[email protected]> https://lists.mpi-forum.org/mailman/listinfo/mpiwg-p2p _______________________________________________ mpiwg-p2p mailing list mpiwg-p2p(a)lists.mpi-forum.org<mailto:[email protected]> https://lists.mpi-forum.org/mailman/listinfo/mpiwg-p2p The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336.

1 0

Re: [mpiwg-p2p] FP16 at MPI Forum in Dec 2017
by Jeff Hammond 13 Nov '17

13 Nov '17

Please link to GitHub ticket, which has good background. Sent from my iPhone > On Nov 13, 2017, at 5:26 PM, HOLMES Daniel <d.holmes(a)epcc.ed.ac.uk> wrote: > > Hi all, > > I’m going to present the attach slide at the MPI BoF on Wednesday at SC17. > > If you have comments/suggestions/changes, please let me know by lunch tomorrow. > > Cheers, > Dan. > >> On 13 Nov 2017, at 14:10, Anthony Skjellum <tony(a)runtimecomputing.com> wrote: >> >> I prefer #2. >> Tony >> >> >> On Mon, Nov 13, 2017 at 12:47 PM, HOLMES Daniel <d.holmes(a)epcc.ed.ac.uk> wrote: >> Hi all, >> >> I need to let Martin know what this WG needs in terms of agenda items. >> >> Will the FP16 proposal be ready for a formal reading at the Dec meeting? I suspect not, because there are still changes being made to the text for a variety of reasons. The announcement deadline for readings is rapidly approaching (7 days from now). >> >> Please vote for one of these options: >> 1) Formal reading of FP16 proposal >> 2) Plenary presentation of current status of FP16 and outstanding questions/issues >> 3) No presentation to the whole Forum >> >> In addition, do we want WG time to progress this proposal? >> >> Cheers, >> Dan. >> -- >> The University of Edinburgh is a charitable body, registered in >> Scotland, with registration number SC005336. >> >> _______________________________________________ >> mpiwg-p2p mailing list >> mpiwg-p2p(a)lists.mpi-forum.org >> https://lists.mpi-forum.org/mailman/listinfo/mpiwg-p2p >> >> >> >> -- >> Tony Skjellum, PhD >> RunTime Computing Solutions, LLC >> tony(a)runtimecomputing.com >> direct: +1-205-918-7514 >> cell: +1-205-807-4968 >> _______________________________________________ >> mpiwg-p2p mailing list >> mpiwg-p2p(a)lists.mpi-forum.org >> https://lists.mpi-forum.org/mailman/listinfo/mpiwg-p2p > > <MPI BoF - Point-to-Point.pptx> > The University of Edinburgh is a charitable body, registered in > Scotland, with registration number SC005336. > _______________________________________________ > mpiwg-p2p mailing list > mpiwg-p2p(a)lists.mpi-forum.org > https://lists.mpi-forum.org/mailman/listinfo/mpiwg-p2p

1 0

Re: [mpiwg-p2p] FP16 at MPI Forum in Dec 2017
by HOLMES Daniel 13 Nov '17

13 Nov '17

Hi all, I’m going to present the attach slide at the MPI BoF on Wednesday at SC17. If you have comments/suggestions/changes, please let me know by lunch tomorrow. Cheers, Dan. On 13 Nov 2017, at 14:10, Anthony Skjellum <tony(a)runtimecomputing.com<mailto:[email protected]>> wrote: I prefer #2. Tony On Mon, Nov 13, 2017 at 12:47 PM, HOLMES Daniel <d.holmes(a)epcc.ed.ac.uk<mailto:[email protected]>> wrote: Hi all, I need to let Martin know what this WG needs in terms of agenda items. Will the FP16 proposal be ready for a formal reading at the Dec meeting? I suspect not, because there are still changes being made to the text for a variety of reasons. The announcement deadline for readings is rapidly approaching (7 days from now). Please vote for one of these options: 1) Formal reading of FP16 proposal 2) Plenary presentation of current status of FP16 and outstanding questions/issues 3) No presentation to the whole Forum In addition, do we want WG time to progress this proposal? Cheers, Dan. -- The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336. _______________________________________________ mpiwg-p2p mailing list mpiwg-p2p(a)lists.mpi-forum.org<mailto:[email protected]> https://lists.mpi-forum.org/mailman/listinfo/mpiwg-p2p -- Tony Skjellum, PhD RunTime Computing Solutions, LLC tony(a)runtimecomputing.com<mailto:[email protected]> direct: +1-205-918-7514 cell: +1-205-807-4968 _______________________________________________ mpiwg-p2p mailing list mpiwg-p2p(a)lists.mpi-forum.org<mailto:[email protected]> https://lists.mpi-forum.org/mailman/listinfo/mpiwg-p2p The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336.

1 0

Re: [mpiwg-p2p] FP16 at MPI Forum in Dec 2017
by Anthony Skjellum 13 Nov '17

13 Nov '17

I prefer #2. Tony On Mon, Nov 13, 2017 at 12:47 PM, HOLMES Daniel <d.holmes(a)epcc.ed.ac.uk> wrote: > Hi all, > > I need to let Martin know what this WG needs in terms of agenda items. > > Will the FP16 proposal be ready for a formal reading at the Dec meeting? I > suspect not, because there are still changes being made to the text for a > variety of reasons. The announcement deadline for readings is rapidly > approaching (7 days from now). > > Please vote for one of these options: > 1) Formal reading of FP16 proposal > 2) Plenary presentation of current status of FP16 and outstanding > questions/issues > 3) No presentation to the whole Forum > > In addition, do we want WG time to progress this proposal? > > Cheers, > Dan. > -- > The University of Edinburgh is a charitable body, registered in > Scotland, with registration number SC005336. > > _______________________________________________ > mpiwg-p2p mailing list > mpiwg-p2p(a)lists.mpi-forum.org > https://lists.mpi-forum.org/mailman/listinfo/mpiwg-p2p > -- Tony Skjellum, PhD RunTime Computing Solutions, LLC tony(a)runtimecomputing.com direct: +1-205-918-7514 cell: +1-205-807-4968

1 0

Re: [mpiwg-p2p] FP16 at MPI Forum in Dec 2017
by Jeff Hammond 13 Nov '17

13 Nov '17

Plenary on FP16 is a good idea. I do not think we are ready for a reading. If there is a working group on FP16, I'd like to dial in. I wanted to attend but it's not practical for me to travel in December. I intend to be at the Portland meeting and we should aspire to do a reading there. Jeff On Mon, Nov 13, 2017 at 9:47 AM, HOLMES Daniel <d.holmes(a)epcc.ed.ac.uk> wrote: > Hi all, > > I need to let Martin know what this WG needs in terms of agenda items. > > Will the FP16 proposal be ready for a formal reading at the Dec meeting? I > suspect not, because there are still changes being made to the text for a > variety of reasons. The announcement deadline for readings is rapidly > approaching (7 days from now). > > Please vote for one of these options: > 1) Formal reading of FP16 proposal > 2) Plenary presentation of current status of FP16 and outstanding > questions/issues > 3) No presentation to the whole Forum > > In addition, do we want WG time to progress this proposal? > > Cheers, > Dan. > -- > The University of Edinburgh is a charitable body, registered in > Scotland, with registration number SC005336. > > _______________________________________________ > mpiwg-p2p mailing list > mpiwg-p2p(a)lists.mpi-forum.org > https://lists.mpi-forum.org/mailman/listinfo/mpiwg-p2p > -- Jeff Hammond jeff.science(a)gmail.com http://jeffhammond.github.io/

1 0

FP16 at MPI Forum in Dec 2017
by HOLMES Daniel 13 Nov '17

13 Nov '17

Hi all, I need to let Martin know what this WG needs in terms of agenda items. Will the FP16 proposal be ready for a formal reading at the Dec meeting? I suspect not, because there are still changes being made to the text for a variety of reasons. The announcement deadline for readings is rapidly approaching (7 days from now). Please vote for one of these options: 1) Formal reading of FP16 proposal 2) Plenary presentation of current status of FP16 and outstanding questions/issues 3) No presentation to the whole Forum In addition, do we want WG time to progress this proposal? Cheers, Dan. -- The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336.

1 0

Re: [mpiwg-p2p] Fwd: Next meeting: **today** 14th August 2017 11am Central US
by HOLMES Daniel 08 Sep '17

08 Sep '17

Hi Martin, This WG has two topics for discussion - I think the 90 minutes in the current agenda/schedule should be sufficient for an update and some discussion on both. Cheers, Dan. On 8 Sep 2017, at 09:37, Martin Schulz <schulzm(a)llnl.gov<mailto:[email protected]>> wrote: Trying again with the right email address. Martin Begin forwarded message: From: "Schulz, Martin" <schulz6(a)llnl.gov<mailto:[email protected]>> Subject: Re: [mpiwg-p2p] Next meeting: **today** 14th August 2017 11am Central US Date: September 7, 2017 at 5:46:15 PM HST To: MPI WG Point To Point Communications working group <mpiwg-p2p(a)lists.mpi-forum.org<mailto:[email protected]>> Hi Dan, We talked about adding this topic late afternoon on Thursday, so that Atsushi can attend remotely (which would be Friday morning for him). Would this work for you and, if so, how much time do the two of you think is necessary? Thanks! Martin On Sep 6, 2017, at 11:31 PM, HOLMES Daniel <d.holmes(a)epcc.ed.ac.uk<mailto:[email protected]>> wrote: Hi Atsushi, It would be good to push this topic forward at the face-to-face meeting - or at least to update folks on the recent progress. Cheers, Dan. On 6 Sep 2017, at 23:21, Atsushi HORI <ahori(a)riken.jp<mailto:[email protected]>> wrote: Hi, Dan and others, 2017/08/15 1:11、Dan Holmes <d.holmes(a)epcc.ed.ac.uk<mailto:[email protected]>> wrote; NB: I’m going to request a small amount of WG time at the next face-to-face meeting for this WG - primarily for FP16 discussions. I ma attending IEEE Cluster and I had a chance to talk with Martin. If you plan to have FP16 discussion in the next meeting, I will attend it remotely. ----- Atsushi HORI ahori(a)riken.jp<mailto:[email protected]> http://aics-sys.riken.jp _______________________________________________ mpiwg-p2p mailing list mpiwg-p2p(a)lists.mpi-forum.org https://lists.mpi-forum.org/mailman/listinfo/mpiwg-p2p -- The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336. _______________________________________________ mpiwg-p2p mailing list mpiwg-p2p(a)lists.mpi-forum.org<mailto:[email protected]> https://lists.mpi-forum.org/mailman/listinfo/mpiwg-p2p _______________________________________________ mpiwg-p2p mailing list mpiwg-p2p(a)lists.mpi-forum.org<mailto:[email protected]> https://lists.mpi-forum.org/mailman/listinfo/mpiwg-p2p The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336.

1 0