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Hi Jim,<br>
<br>
I like that change. On a side note: are we really still calling them
"info hints" in this context rather than "info assertions"?<br>
<br>
Cheers,<br>
Dan.<br>
<br>
<div class="moz-cite-prefix">On 09/02/2016 15:51, Jim Dinan wrote:<br>
</div>
<blockquote
cite="mid:CAOoEU4FiXKpMhSG9g_Wm47uH-QXvy_wXA72VOtkfOBLL3X50fQ@mail.gmail.com"
type="cite">
<div dir="ltr">Hi All,
<div><br>
</div>
<div>I'm preparing the updated draft of info assertions for a
reading in March. Where did we land on an advice regarding
tools? Do we want advice (1) to users, that they info keys
may impact tools and/or (2) to tools that they should check
info?</div>
<div><br>
</div>
<div>For instance, we could extend the current advice with the
following sentence:</div>
<div><span class=""><br>
</span></div>
<div><span class="">Setting info hints on the predefined
communicators </span><span class="">\const</span><span
class="">{</span><span class="">MPI</span><span class="">\_</span><span
class="">COMM</span><span class="">\_</span><span class="">WORLD</span><span
class="">} </span><span class="">and </span><span class="">\const</span><span
class="">{</span><span class="">MPI</span><span class="">\_</span><span
class="">COMM</span><span class="">\_</span><span class="">SELF</span><span
class="">}</span><span class=""> may have unintended
effects, as changes to these </span>global objects may
affect all components of the application, including
libraries. <span style="background-color:rgb(255,255,0)">The
usage of info hints may also impact the effectiveness of
tools.</span></div>
<div><span style="background-color:rgb(255,255,0)"><br>
</span></div>
<div><span style="background-color:rgb(255,255,255)"> ~Jim.</span></div>
</div>
<div class="gmail_extra"><br>
<div class="gmail_quote">On Fri, Dec 18, 2015 at 5:24 AM,
Marc-Andre Hermanns <span dir="ltr"><<a
moz-do-not-send="true"
href="mailto:hermanns@jara.rwth-aachen.de" target="_blank"><a class="moz-txt-link-abbreviated" href="mailto:hermanns@jara.rwth-aachen.de">hermanns@jara.rwth-aachen.de</a></a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex"><span
class="">Hi Jeff,<br>
<br>
> at the moment we don't handle MPI_THREAD_MULTIPLE
at all. But we want<br>
> to get there ;-)<br>
><br>
><br>
> You should vote for endpoints, as this may help you
out here,<br>
> particularly if users start mapping endpoints 1:1 w/
threads.<br>
<br>
</span>That would certainly ease things for us in these
situations.<br>
Unfortunately endpoints force use to adapt other
infrastructure in our<br>
measurement system.<br>
<span class=""><br>
> b) Creating a derived datatype on the fly to add
tool-level data to<br>
> the original payload may induce a large overhead
in practically<br>
> _every_ send & receive operation and perturb
the measurement.<br>
><br>
><br>
> You should evaluate this experimentally. I wrote a
simple test<br>
> (<a moz-do-not-send="true"
href="https://github.com/jeffhammond/BigMPI/blob/master/test/perf/typepiggy.c"
rel="noreferrer" target="_blank">https://github.com/jeffhammond/BigMPI/blob/master/test/perf/typepiggy.c</a>)<br>
> and measured 1.5 us per call of overhead to create a
datatype. That<br>
> is not significant except for very small messages.<br>
<br>
</span>Thanks for the pointer. You are right. I should
evaluate this further.<br>
1.5us does indeed seem tolerable. I wonder how the influence
of the<br>
derived datatype is on overall messaging performance,
though.<br>
<br>
This is also something I should evaluate in the process.<br>
<span class=""><br>
Cheers,<br>
Marc-Andre<br>
<br>
--<br>
Marc-Andre Hermanns<br>
Jülich Aachen Research Alliance,<br>
High Performance Computing (JARA-HPC)<br>
Jülich Supercomputing Centre (JSC)<br>
<br>
Schinkelstrasse 2<br>
52062 Aachen<br>
Germany<br>
<br>
Phone: <a moz-do-not-send="true"
href="tel:%2B49%202461%2061%202509"
value="+492461612509">+49 2461 61 2509</a> | <a
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href="http://www.jara.org/jara-hpc" rel="noreferrer"
target="_blank">www.jara.org/jara-hpc</a><br>
</span>email: <a moz-do-not-send="true"
href="mailto:hermanns@jara.rwth-aachen.de">hermanns@jara.rwth-aachen.de</a><br>
<br>
<br>
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<pre class="moz-signature" cols="72">--
Dan Holmes
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