<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
</head>
<body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">
Hi Junchao Zhang,
<div class=""><br class="">
</div>
<div class="">You are correct - the neighbourhood collectives send messages to (and receive messages from) only neighbouring MPI processes, as defined by the virtual topology. However, it is possible to use point-to-point, single-sided, or normal collective
functions to send (and receive) messages between *any* MPI processes in a communicator, irrespective of the presence/structure of a virtual topology.<br class="">
<div class=""><br class="webkit-block-placeholder">
</div>
<div class="">
<div style="color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">
For your use-case (if I understand it correctly), you should specify a symmetric graph - each process specifies to MPI_DIST_GRAPH_CREATE_ADJACENT all the processes it wishes to communicate with (both sending and receiving) during subsequent calls to MPI_NEIGHBOR_ALLTOALLV.</div>
<div style="color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">
<br class="Apple-interchange-newline">
Cheers,</div>
<div style="color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">
Dan.</div>
<div style="color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">
—<br class="">
Dr Daniel Holmes PhD<br class="">
Applications Consultant in HPC Research<br class="">
<a href="mailto:d.holmes@epcc.ed.ac.uk" class="">d.holmes@epcc.ed.ac.uk</a><br class="">
Phone: +44 (0) 131 651 3465<br class="">
Mobile: +44 (0) 7940 524 088<br class="">
Address: Room 3415, JCMB, The King’s Buildings, Edinburgh, EH9 3FD</div>
<div style="color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">
—</div>
<div style="color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">
The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336.</div>
<div style="color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">
—</div>
</div>
<br class="">
<div>
<blockquote type="cite" class="">
<div class="">On 23 Jul 2018, at 15:45, Junchao Zhang <<a href="mailto:jczhang@mcs.anl.gov" class="">jczhang@mcs.anl.gov</a>> wrote:</div>
<br class="Apple-interchange-newline">
<div class="">
<div dir="ltr" class="">Hello, Dan,<br class="">
I am interested in MPI_Neighbor_alltoallv. From its arguments, I do not see one can send a message to a neighbor not specified in the graph created by
<span style="font-size:small;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline" class="">
for example, </span>MPI_Dist_graph_create_adjacent.</div>
<div class="gmail_extra"><br clear="all" class="">
<div class="">
<div class="gmail_signature" data-smartmail="gmail_signature">
<div dir="ltr" class="">--Junchao Zhang</div>
</div>
</div>
<br class="">
<div class="gmail_quote">On Mon, Jul 23, 2018 at 5:51 AM, HOLMES Daniel <span dir="ltr" class="">
<<a href="mailto:d.holmes@epcc.ed.ac.uk" target="_blank" class="">d.holmes@epcc.ed.ac.uk</a>></span> wrote:<br class="">
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div style="word-wrap:break-word" class="">Hi Junchao Zhang,
<div class=""><br class="">
</div>
<div class="">My understanding of the current API for MPI-3.1 is that:</div>
<div class=""><br class="">
</div>
<div class="">1) the virtual topology does not actually restrict communication via the communicator to the edges specified in the topology - messages can be sent along any edge in either direction, and even between pairs of processes for which no edge was specified.</div>
<div class=""><br class="">
</div>
<div class="">2) the virtual topology can be specified as a symmetric graph - for every ‘forward’ edge (e.g. from A to B), the ‘backward’ edge (i.e. from B to A) can be included as well.</div>
<div class=""><br class="">
</div>
<div class="">3) there is already language in the MPI Standard regarding how MPI handles symmetric and non-symmetric graph topologies for neighbourhood collective operations.</div>
<div class=""><br class="">
</div>
<div class="">Thus, there is no need to create two distributed graph topology communicators to achieve ‘forward and backward communication along the edges’.<br class="">
<div class="">
<div style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; word-wrap: break-word;" class="">
<br class="m_-3269555800436358659Apple-interchange-newline">
Cheers,</div>
<div style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; word-wrap: break-word;" class="">
Dan.</div>
<div style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; word-wrap: break-word;" class="">
—<br class="">
Dr Daniel Holmes PhD<br class="">
Applications Consultant in HPC Research<br class="">
<a href="mailto:d.holmes@epcc.ed.ac.uk" target="_blank" class="">d.holmes@epcc.ed.ac.uk</a><br class="">
Phone: +44 (0) 131 651 3465<br class="">
Mobile: +44 (0) 7940 524 088<br class="">
Address: Room 3415, JCMB, The King’s Buildings, Edinburgh, EH9 3FD</div>
<div style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; word-wrap: break-word;" class="">
—</div>
<div style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; word-wrap: break-word;" class="">
The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336.</div>
<div style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; word-wrap: break-word;" class="">
—</div>
</div>
<div class="">
<div class="h5"><br class="">
<div class="">
<blockquote type="cite" class="">
<div class="">On 15 Jul 2018, at 10:42, Anthony Skjellum <<a href="mailto:tony@runtimecomputing.com" target="_blank" class="">tony@runtimecomputing.com</a>> wrote:</div>
<br class="m_-3269555800436358659Apple-interchange-newline">
<div class="">
<div dir="ltr" class="">Hi, I just saw this.
<div class=""><br class="">
<div class="">We definitely need to consider this concern. </div>
<div class=""><br class="">
</div>
<div class="">I also need to go review the APIs.</div>
<div class=""><br class="">
</div>
<div class="">Thanks,</div>
<div class="">Tony</div>
<div class=""><br class="">
</div>
</div>
</div>
<div class="gmail_extra"><br class="">
<div class="gmail_quote">On Sat, Jul 14, 2018 at 12:27 AM, Junchao Zhang <span dir="ltr" class="">
<<a href="mailto:jczhang@mcs.anl.gov" target="_blank" class="">jczhang@mcs.anl.gov</a>></span> wrote:<br class="">
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div dir="ltr" class="">
<div class=""> I want to try MPI neighborhood collectives. I have a communication graph and want to do both forward and backward communication along the edges. With current APIs, it looks I need to create two comm_dist_graphs. It is a waste since MPI implementations
can do similar optimizations for the two.</div>
<div class=""> Should MPI support this scenario? Thanks.</div>
<span class="m_-3269555800436358659HOEnZb"><font color="#888888" class=""><br clear="all" class="">
<div class="">
<div class="m_-3269555800436358659m_-3099374219715359755gmail_signature">
<div dir="ltr" class="">--Junchao Zhang</div>
</div>
</div>
</font></span></div>
<br class="">
______________________________<wbr class="">_________________<br class="">
mpiwg-coll mailing list<br class="">
<a href="mailto:mpiwg-coll@lists.mpi-forum.org" target="_blank" class="">mpiwg-coll@lists.mpi-forum.org</a><br class="">
<a href="https://lists.mpi-forum.org/mailman/listinfo/mpiwg-coll" rel="noreferrer" target="_blank" class="">https://lists.mpi-forum.org/ma<wbr class="">ilman/listinfo/mpiwg-coll</a><br class="">
<br class="">
</blockquote>
</div>
<br class="">
<br clear="all" class="">
<div class=""><br class="">
</div>
-- <br class="">
<div class="m_-3269555800436358659gmail_signature" data-smartmail="gmail_signature">
<div dir="ltr" class="">
<div class="">Tony Skjellum, PhD<br class="">
RunTime Computing Solutions, LLC<br class="">
<a href="mailto:tony@runtimecomputing.com" target="_blank" class="">tony@runtimecomputing.com</a><br class="">
direct: +1-205-918-7514<br class="">
cell: +1-205-807-4968<br class="">
</div>
</div>
</div>
</div>
______________________________<wbr class="">_________________<br class="">
mpiwg-coll mailing list<br class="">
<a href="mailto:mpiwg-coll@lists.mpi-forum.org" target="_blank" class="">mpiwg-coll@lists.mpi-forum.org</a><br class="">
<a href="https://lists.mpi-forum.org/mailman/listinfo/mpiwg-coll" target="_blank" class="">https://lists.mpi-forum.org/<wbr class="">mailman/listinfo/mpiwg-coll</a><br class="">
</div>
</blockquote>
</div>
<br class="">
</div>
</div>
</div>
</div>
<br class="">
The University of Edinburgh is a charitable body, registered in<br class="">
Scotland, with registration number SC005336.<br class="">
<br class="">
______________________________<wbr class="">_________________<br class="">
mpiwg-coll mailing list<br class="">
<a href="mailto:mpiwg-coll@lists.mpi-forum.org" class="">mpiwg-coll@lists.mpi-forum.org</a><br class="">
<a href="https://lists.mpi-forum.org/mailman/listinfo/mpiwg-coll" rel="noreferrer" target="_blank" class="">https://lists.mpi-forum.org/<wbr class="">mailman/listinfo/mpiwg-coll</a><br class="">
<br class="">
</blockquote>
</div>
<br class="">
</div>
_______________________________________________<br class="">
mpiwg-coll mailing list<br class="">
<a href="mailto:mpiwg-coll@lists.mpi-forum.org" class="">mpiwg-coll@lists.mpi-forum.org</a><br class="">
https://lists.mpi-forum.org/mailman/listinfo/mpiwg-coll<br class="">
</div>
</blockquote>
</div>
<br class="">
</div>
</body>
</html>