<div dir="ltr">Rolf:<div><br>Before anybody spends any time analyzing how we handle segmented addressing, I want you to provide an example of a platform where this is relevant. What system can you boot today that needs this and what MPI libraries have expressed an interest in supporting it?</div><div><br></div><div>For anyone who didn't hear, ISO C and C++ have finally committed to twos-complement integers (<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0907r1.html">http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0907r1.html</a>, <a href="http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2218.htm">http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2218.htm</a>) because modern programmers should not be limited by hardware designs from the 1960s. We should similarly not waste our time on obsolete features like segmentation.</div><div><br></div><div>Jeff</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Thu, Oct 24, 2019 at 10:13 AM Rolf Rabenseifner via mpiwg-large-counts <<a href="mailto:mpiwg-large-counts@lists.mpi-forum.org">mpiwg-large-counts@lists.mpi-forum.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">> I think that changes the conversation entirely, right?<br>
<br>
Not the first part, the state-of-current-MPI.<br>
<br>
It may change something for the future, or a new interface may be needed.<br>
<br>
Please, can you describe how MPI_Get_address can work with the <br>
different variables from different memory segments.<br>
<br>
Or whether a completely new function or a set of functions is needed.<br>
<br>
If we can still express variables from all memory segments as <br>
input to MPI_Get_address, there may be still a way to flatten<br>
the result of some internal address-iquiry into a flattened<br>
signed integer with the same behavior as MPI_Aint today.<br>
<br>
If this is impossible, then new way of thinking and solution <br>
may be needed.<br>
<br>
I really want to see examples for all current stuff as you<br>
mentioned in your last email.<br>
<br>
Best regards<br>
Rolf<br>
<br>
----- Original Message -----<br>
> From: "Jeff Squyres" <<a href="mailto:jsquyres@cisco.com" target="_blank">jsquyres@cisco.com</a>><br>
> To: "Rolf Rabenseifner" <<a href="mailto:rabenseifner@hlrs.de" target="_blank">rabenseifner@hlrs.de</a>><br>
> Cc: "mpiwg-large-counts" <<a href="mailto:mpiwg-large-counts@lists.mpi-forum.org" target="_blank">mpiwg-large-counts@lists.mpi-forum.org</a>><br>
> Sent: Thursday, October 24, 2019 5:27:31 PM<br>
> Subject: Re: [Mpiwg-large-counts] Large Count - the principles for counts, sizes, and byte and nonbyte displacements<br>
<br>
> On Oct 24, 2019, at 11:15 AM, Rolf Rabenseifner<br>
> <<a href="mailto:rabenseifner@hlrs.de" target="_blank">rabenseifner@hlrs.de</a><mailto:<a href="mailto:rabenseifner@hlrs.de" target="_blank">rabenseifner@hlrs.de</a>>> wrote:<br>
> <br>
> For me, it looked like that there was some misunderstanding<br>
> of the concept that absolute and relative addresses<br>
> and number of bytes that can be stored in MPI_Aint.<br>
> <br>
> ...with the caveat that MPI_Aint -- as it is right now -- does not support<br>
> modern segmented memory systems (i.e., where you need more than a small number<br>
> of bits to indicate the segment where the memory lives).<br>
> <br>
> I think that changes the conversation entirely, right?<br>
> <br>
> --<br>
> Jeff Squyres<br>
> <a href="mailto:jsquyres@cisco.com" target="_blank">jsquyres@cisco.com</a><mailto:<a href="mailto:jsquyres@cisco.com" target="_blank">jsquyres@cisco.com</a>><br>
<br>
-- <br>
Dr. Rolf Rabenseifner . . . . . . . . . .. email <a href="mailto:rabenseifner@hlrs.de" target="_blank">rabenseifner@hlrs.de</a> .<br>
High Performance Computing Center (HLRS) . phone ++49(0)711/685-65530 .<br>
University of Stuttgart . . . . . . . . .. fax ++49(0)711 / 685-65832 .<br>
Head of Dpmt Parallel Computing . . . <a href="http://www.hlrs.de/people/rabenseifner" rel="noreferrer" target="_blank">www.hlrs.de/people/rabenseifner</a> .<br>
Nobelstr. 19, D-70550 Stuttgart, Germany . . . . (Office: Room 1.307) .<br>
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</blockquote></div><br clear="all"><div><br></div>-- <br><div dir="ltr" class="gmail_signature">Jeff Hammond<br><a href="mailto:jeff.science@gmail.com" target="_blank">jeff.science@gmail.com</a><br><a href="http://jeffhammond.github.io/" target="_blank">http://jeffhammond.github.io/</a></div>