<html>
<head>
<meta content="text/html; charset=windows-1252"
http-equiv="Content-Type">
</head>
<body bgcolor="#FFFFFF" text="#000000">
<div class="moz-cite-prefix">Interesting read. The essential message
is:<br>
"Thus, we believe that a discussion on threads versus processes
boils down to “shared everything by default” versus “shared
nothing by default”.<br>
We came to the same conclusion in a discussion some time ago. So
the choice doesn't affect performance, but it strongly affects the
code.<br>
For Gromacs I think it's still convenient to have
processes+threads, since we have many data structures with many
small arrays that change at domain decomposition time that are
needed by all threads in a domain. Sharing all these through MPI3
is tedious.<br>
<br>
Cheers,<br>
<br>
Berk<br>
<br>
On 10/08/2015 01:04 PM, Szilárd Páll wrote:<br>
</div>
<blockquote
cite="mid:CANnYEw7DoDXsQZEXODqANB0q3ChEvxkR8wsQr78kObRrEWr-0g@mail.gmail.com"
type="cite">
<meta http-equiv="Content-Type" content="text/html;
charset=windows-1252">
<div dir="ltr">
<div><br>
</div>
<div>"We believe that portions of the HPC community have adopted
the point of view that somehow threads are “necessary” in
order to utilize such [manycore/SMP] systems, (1) without
fully understanding the alternatives, including MPI 3
functionality, (2) underestimating the difficulty of utilizing
threads efficiently, and (3) without appreciating the
similarities of threads and processes. This short paper, due
to space constraints, focuses exclusively on issue (3) since
we feel it has gotten virtually no attention."<br>
</div>
<div><br>
</div>
<a moz-do-not-send="true"
href="http://www.orau.gov/hpcor2015/whitepapers/Exascale_Computing_without_Threads-Barry_Smith.pdf">http://www.orau.gov/hpcor2015/whitepapers/Exascale_Computing_without_Threads-Barry_Smith.pdf</a><br
clear="all">
<div><br clear="all">
<div>
<div class="gmail_signature">--<br>
Szilárd</div>
</div>
</div>
</div>
<br>
<fieldset class="mimeAttachmentHeader"></fieldset>
<br>
</blockquote>
<br>
</body>
</html>