July 2012 - mpiwg-rma - mailman3.cels.anl.gov

Re: [Mpi3-rma] Disp_unit in allocate_shared should be returned by win_shared_query?
by Torsten Hoefler 18 Jul '12

18 Jul '12

Ok, I implemented it in approved/one-sided. Please review new document on https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/284 . Thanks, Torsten On Wed, Jul 18, 2012 at 10:54:36AM -0500, Jeff Hammond wrote: > makes sense. +1 from me. > > On Wed, Jul 18, 2012 at 10:53 AM, William Gropp <wgropp(a)illinois.edu> wrote: > > I agree - I vote for adding it. > > > > Bill > > > > William Gropp > > Director, Parallel Computing Institute > > Deputy Director for Research > > Institute for Advanced Computing Applications and Technologies > > Paul and Cynthia Saylor Professor of Computer Science > > University of Illinois Urbana-Champaign > > > > > > > > On Jul 18, 2012, at 10:22 AM, sreeram potluri wrote: > > > >> I'd also vote for adding it, to be consistent. > >> > >> Thanks, > >> Sreeram > >> > >> On Wed, Jul 18, 2012 at 9:54 AM, Torsten Hoefler <htor(a)illinois.edu> wrote: > >>> Hi group, > >>> > >>> Hubert just brought this up at the ticket. It's a valid point but may be > >>> a bit late. Unfortunately, we're far away from a quorum at the Forum (we > >>> have only Sreeram and me in the room). So I am broadcasting the question > >>> to the mailinglist. > >>> > >>> Any opinions? I'd vote to add it also (as part of yesterday's change). > >>> > >>> Thanks, > >>> Torsten > >>> > >>> -- > >>> ### qreharg rug ebs fv crryF ------------- http://www.unixer.de/ ----- > >>> Torsten Hoefler | Performance Modeling and Simulation Lead > >>> Blue Waters Directorate | University of Illinois (UIUC) > >>> 1205 W Clark Street | Urbana, IL, 61801 > >>> NCSA Building | +01 (217) 244-7736 > >>> _______________________________________________ > >>> mpi3-rma mailing list > >>> mpi3-rma(a)lists.mpi-forum.org > >>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma > >> _______________________________________________ > >> mpi3-rma mailing list > >> mpi3-rma(a)lists.mpi-forum.org > >> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma > > > > _______________________________________________ > > mpi3-rma mailing list > > mpi3-rma(a)lists.mpi-forum.org > > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma > > > > -- > Jeff Hammond > Argonne Leadership Computing Facility > University of Chicago Computation Institute > jhammond(a)alcf.anl.gov / (630) 252-5381 > http://www.linkedin.com/in/jeffhammond > https://wiki.alcf.anl.gov/parts/index.php/User:Jhammond > _______________________________________________ > mpi3-rma mailing list > mpi3-rma(a)lists.mpi-forum.org > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma > -- ### qreharg rug ebs fv crryF ------------- http://www.unixer.de/ ----- Torsten Hoefler | Performance Modeling and Simulation Lead Blue Waters Directorate | University of Illinois (UIUC) 1205 W Clark Street | Urbana, IL, 61801 NCSA Building | +01 (217) 244-7736

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Re: [Mpi3-rma] notes from 5pm Tuesday meeting @ July 2012 Forum
by Underwood, Keith D 18 Jul '12

18 Jul '12

>From the perspective of wanting to do an atomic, that value has changed. If it happened to match bitwise, <shrug> no harm, no foul. Keith > -----Original Message----- > From: mpi3-rma-bounces(a)lists.mpi-forum.org [mailto:mpi3-rma- > bounces(a)lists.mpi-forum.org] On Behalf Of Jeff Hammond > Sent: Wednesday, July 18, 2012 11:50 AM > To: MPI 3.0 Remote Memory Access working group > Subject: Re: [Mpi3-rma] notes from 5pm Tuesday meeting @ July 2012 > Forum > > has x changed below? > > { > double x = 0.3; > x *= 7; > x /= 7; > } > > do you really want to add a paragraph on how floating point arithmetic works > just so that users understand what you mean by "has not changed"? > > jeff > > On Wed, Jul 18, 2012 at 10:25 AM, Underwood, Keith D > <keith.d.underwood(a)intel.com> wrote: > > Because that would really suck for the user? :-) The == operator is > > quite sensible from the "has this changed" perspective... And, > > meaningless mathematically for floating-point > > > > Keith > > > >> -----Original Message----- > >> From: mpi3-rma-bounces(a)lists.mpi-forum.org [mailto:mpi3-rma- > >> bounces(a)lists.mpi-forum.org] On Behalf Of Jeff Hammond > >> Sent: Wednesday, July 18, 2012 11:22 AM > >> To: MPI 3.0 Remote Memory Access working group > >> Subject: Re: [Mpi3-rma] notes from 5pm Tuesday meeting @ July 2012 > >> Forum > >> > >> i meant make the user cast. i think you underestimate how often > >> scientists falsely think that == acts on floating point numbers in a > >> mathematically sensible way. > >> > >> On Wed, Jul 18, 2012 at 10:18 AM, Underwood, Keith D > >> <keith.d.underwood(a)intel.com> wrote: > >> > Yes, the MPI library could certainly make that choice in how it > >> > used the > >> hardware... > >> > > >> >> -----Original Message----- > >> >> From: mpi3-rma-bounces(a)lists.mpi-forum.org [mailto:mpi3-rma- > >> >> bounces(a)lists.mpi-forum.org] On Behalf Of Jeff Hammond > >> >> Sent: Wednesday, July 18, 2012 11:09 AM > >> >> To: MPI 3.0 Remote Memory Access working group > >> >> Subject: Re: [Mpi3-rma] notes from 5pm Tuesday meeting @ July 2012 > >> >> Forum > >> >> > >> >> So your A==B comparison is at the level of bits? Couldn't you > >> >> just cast double to long then? > >> >> > >> >> Jeff > >> >> > >> >> On Wed, Jul 18, 2012 at 10:03 AM, Underwood, Keith D > >> >> <keith.d.underwood(a)intel.com> wrote: > >> >> > success=0; > >> >> > while (!success) { > >> >> > A=B; // B is remote, obtained using RMA > >> >> > C=(A*D+E*F) / G; // Everything local, all are doubles > >> >> > if (B == A) {B=C; success = 1}; // This is CAS } > >> >> > > >> >> > And now you have done a relatively complicated thing on B > >> >> > atomically, > >> >> though you will suffer if there is contention... > >> >> > > >> >> > Keith > >> >> > > >> >> >> -----Original Message----- > >> >> >> From: mpi3-rma-bounces(a)lists.mpi-forum.org [mailto:mpi3-rma- > >> >> >> bounces(a)lists.mpi-forum.org] On Behalf Of Jeff Hammond > >> >> >> Sent: Tuesday, July 17, 2012 11:03 PM > >> >> >> To: MPI 3.0 Remote Memory Access working group > >> >> >> Subject: Re: [Mpi3-rma] notes from 5pm Tuesday meeting @ July > >> >> >> 2012 Forum > >> >> >> > >> >> >> What do you mean by "arbitrary atomics"? Are you proposing to > >> >> >> do something evil with bitwise comparison on floating-point > >> >> >> numbers to realize something other than the obvious meaning of > >> >> >> CAS on a float type? If so, just say it, then do it the right way. > >> >> >> > >> >> >> We should consider how users will interpret CAS on doubles, for > >> >> >> example, and not what some low-level network person can dream > >> >> >> up to do with this operation. > >> >> >> > >> >> >> What architecture implements remote CAS on floating-point types > >> >> >> in hardware right now? Who is proposing it? I invoke the > >> >> >> standard (and a bit worn out) argument about implementing MPI-3 > >> >> >> entirely in hardware and say that unless someone knows how to > >> >> >> do CAS for doubles, it cannot be in the standard. > >> >> >> > >> >> >> And to be perfectly honest, I have utterly no idea what you > >> >> >> really mean right now so it would be very helpful if you could > >> >> >> be very explicit about what you mean by CAS on floating point > >> >> >> types. What measure are you using for comparison? Does this > >> >> >> have any reason meaning in the context of floating point > arithmetic? > >> >> >> > >> >> >> Jeff > >> >> >> > >> >> >> On Tue, Jul 17, 2012 at 9:40 PM, Underwood, Keith D > >> >> >> <keith.d.underwood(a)intel.com> wrote: > >> >> >> > Floating-point CAS is valid as a way to implement "if this > >> >> >> > hasn't changed, > >> >> >> put the results of this operation in place". It gives you a > >> >> >> (moderately expensive, not very fair) way to build a form of > >> >> >> arbitrary > >> >> atomics. > >> >> >> > > >> >> >> > Keith > >> >> >> > > >> >> >> >> -----Original Message----- > >> >> >> >> From: mpi3-rma-bounces(a)lists.mpi-forum.org [mailto:mpi3- > rma- > >> >> >> >> bounces(a)lists.mpi-forum.org] On Behalf Of Jeff Hammond > >> >> >> >> Sent: Tuesday, July 17, 2012 7:26 PM > >> >> >> >> To: MPI 3.0 Remote Memory Access working group > >> >> >> >> Subject: Re: [Mpi3-rma] notes from 5pm Tuesday meeting @ > >> >> >> >> July > >> >> >> >> 2012 Forum > >> >> >> >> > >> >> >> >> I don't know that floating-point compare is well-defined. > >> >> >> >> You really have ask "if abs(x-y)<tolerance" and not "if x==y". > >> >> >> >> > >> >> >> >> I think only fixed-point types should be valid for CAS. > >> >> >> >> > >> >> >> >> Jeff > >> >> >> >> > >> >> >> >> On Tue, Jul 17, 2012 at 6:14 PM, Dave Goodell > >> >> >> >> <goodell(a)mcs.anl.gov> > >> >> >> wrote: > >> >> >> >> > Discussed the complex types in COMPARE_AND_SWAP issue. > >> >> "Fortran > >> >> >> >> Integer" category is permitted, but "Complex" category is > >> >> >> >> not, primarily because of width. Since "Fortran Integer" > >> >> >> >> contains wide types, shouldn't we just permit "Complex" and > >> >> >> >> "Floating point" as well? Consensus was to stick with the > >> >> >> >> existing text which permits only "C integer, Fortran > >> >> >> >> integer, Logical, Multi-language types, or > >> >> Byte". > >> >> >> >> > > >> >> >> >> > Group review (esp. Jim & Sreeram): > >> >> >> >> > https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/187 > >> >> >> >> > > >> >> >> >> > incorporate Jim suggested change (Torsten): > >> >> >> >> > https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/271 > >> >> >> >> > > >> >> >> >> > we think we are unaffected, but need a second check (Jim): > >> >> >> >> > https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/278 > >> >> >> >> > > >> >> >> >> > Double-check that C++ is not referenced in the RMA chapter > >> >> (Pavan): > >> >> >> >> > https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/281 > >> >> >> >> > > >> >> >> >> > Needs review (Dave): > >> >> >> >> > https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/300 > >> >> >> >> > > >> >> >> >> > Think unaffected, but slim chance of Rput/Rget being > >> >> >> >> > affected > >> >> (Pavan): > >> >> >> >> > https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/317 > >> >> >> >> > > >> >> >> >> > Need to check implementation of various (4?) "flush is non- > local" > >> >> >> >> > changes (Dave): > >> >> >> >> > https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/270 > >> >> >> >> > > >> >> >> >> > Need to check disp_unit change (Jim & Sreeram): > >> >> >> >> > https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/284 > >> >> >> >> > > >> >> >> >> > After the above items have all been dealt with, all > >> >> >> >> > chapter committee > >> >> >> >> members should re-read the whole chapter in the *clean* > >> >> >> >> document (the one _without_ the changebars and colored text) > >> >> >> >> to look for obvious typos and inconsistencies. > >> >> >> >> > > >> >> >> >> > -Dave > >> >> >> >> > > >> >> >> >> > > >> >> >> >> > _______________________________________________ > >> >> >> >> > mpi3-rma mailing list > >> >> >> >> > mpi3-rma(a)lists.mpi-forum.org > >> >> >> >> > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma > >> >> >> >> > >> >> >> >> > >> >> >> >> > >> >> >> >> -- > >> >> >> >> Jeff Hammond > >> >> >> >> Argonne Leadership Computing Facility University of Chicago > >> >> >> >> Computation Institute jhammond(a)alcf.anl.gov / (630) > >> >> >> >> 252-5381 http://www.linkedin.com/in/jeffhammond > >> >> >> >> https://wiki.alcf.anl.gov/parts/index.php/User:Jhammond > >> >> >> >> > >> >> >> >> _______________________________________________ > >> >> >> >> mpi3-rma mailing list > >> >> >> >> mpi3-rma(a)lists.mpi-forum.org > >> >> >> >> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma > >> >> >> > > >> >> >> > _______________________________________________ > >> >> >> > mpi3-rma mailing list > >> >> >> > mpi3-rma(a)lists.mpi-forum.org > >> >> >> > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma > >> >> >> > >> >> >> > >> >> >> > >> >> >> -- > >> >> >> Jeff Hammond > >> >> >> Argonne Leadership Computing Facility University of Chicago > >> >> >> Computation Institute jhammond(a)alcf.anl.gov / (630) > >> >> >> 252-5381 http://www.linkedin.com/in/jeffhammond > >> >> >> https://wiki.alcf.anl.gov/parts/index.php/User:Jhammond > >> >> >> _______________________________________________ > >> >> >> mpi3-rma mailing list > >> >> >> mpi3-rma(a)lists.mpi-forum.org > >> >> >> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma > >> >> > > >> >> > _______________________________________________ > >> >> > mpi3-rma mailing list > >> >> > mpi3-rma(a)lists.mpi-forum.org > >> >> > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma > >> >> > >> >> > >> >> > >> >> -- > >> >> Jeff Hammond > >> >> Argonne Leadership Computing Facility University of Chicago > >> >> Computation Institute jhammond(a)alcf.anl.gov / (630) > >> >> 252-5381 http://www.linkedin.com/in/jeffhammond > >> >> https://wiki.alcf.anl.gov/parts/index.php/User:Jhammond > >> >> _______________________________________________ > >> >> mpi3-rma mailing list > >> >> mpi3-rma(a)lists.mpi-forum.org > >> >> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma > >> > > >> > _______________________________________________ > >> > mpi3-rma mailing list > >> > mpi3-rma(a)lists.mpi-forum.org > >> > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma > >> > >> > >> > >> -- > >> Jeff Hammond > >> Argonne Leadership Computing Facility University of Chicago > >> Computation Institute jhammond(a)alcf.anl.gov / (630) > >> 252-5381 http://www.linkedin.com/in/jeffhammond > >> https://wiki.alcf.anl.gov/parts/index.php/User:Jhammond > >> _______________________________________________ > >> mpi3-rma mailing list > >> mpi3-rma(a)lists.mpi-forum.org > >> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma > > > > _______________________________________________ > > mpi3-rma mailing list > > mpi3-rma(a)lists.mpi-forum.org > > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma > > > > -- > Jeff Hammond > Argonne Leadership Computing Facility > University of Chicago Computation Institute jhammond(a)alcf.anl.gov / (630) > 252-5381 http://www.linkedin.com/in/jeffhammond > https://wiki.alcf.anl.gov/parts/index.php/User:Jhammond > _______________________________________________ > mpi3-rma mailing list > mpi3-rma(a)lists.mpi-forum.org > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma

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Re: [Mpi3-rma] Disp_unit in allocate_shared should be returned by win_shared_query?
by Jeff Hammond 18 Jul '12

18 Jul '12

makes sense. +1 from me. On Wed, Jul 18, 2012 at 10:53 AM, William Gropp <wgropp(a)illinois.edu> wrote: > I agree - I vote for adding it. > > Bill > > William Gropp > Director, Parallel Computing Institute > Deputy Director for Research > Institute for Advanced Computing Applications and Technologies > Paul and Cynthia Saylor Professor of Computer Science > University of Illinois Urbana-Champaign > > > > On Jul 18, 2012, at 10:22 AM, sreeram potluri wrote: > >> I'd also vote for adding it, to be consistent. >> >> Thanks, >> Sreeram >> >> On Wed, Jul 18, 2012 at 9:54 AM, Torsten Hoefler <htor(a)illinois.edu> wrote: >>> Hi group, >>> >>> Hubert just brought this up at the ticket. It's a valid point but may be >>> a bit late. Unfortunately, we're far away from a quorum at the Forum (we >>> have only Sreeram and me in the room). So I am broadcasting the question >>> to the mailinglist. >>> >>> Any opinions? I'd vote to add it also (as part of yesterday's change). >>> >>> Thanks, >>> Torsten >>> >>> -- >>> ### qreharg rug ebs fv crryF ------------- http://www.unixer.de/ ----- >>> Torsten Hoefler | Performance Modeling and Simulation Lead >>> Blue Waters Directorate | University of Illinois (UIUC) >>> 1205 W Clark Street | Urbana, IL, 61801 >>> NCSA Building | +01 (217) 244-7736 >>> _______________________________________________ >>> mpi3-rma mailing list >>> mpi3-rma(a)lists.mpi-forum.org >>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma >> _______________________________________________ >> mpi3-rma mailing list >> mpi3-rma(a)lists.mpi-forum.org >> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma > > _______________________________________________ > mpi3-rma mailing list > mpi3-rma(a)lists.mpi-forum.org > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma -- Jeff Hammond Argonne Leadership Computing Facility University of Chicago Computation Institute jhammond(a)alcf.anl.gov / (630) 252-5381 http://www.linkedin.com/in/jeffhammond https://wiki.alcf.anl.gov/parts/index.php/User:Jhammond

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Re: [Mpi3-rma] Disp_unit in allocate_shared should be returned by win_shared_query?
by William Gropp 18 Jul '12

18 Jul '12

I agree - I vote for adding it. Bill William Gropp Director, Parallel Computing Institute Deputy Director for Research Institute for Advanced Computing Applications and Technologies Paul and Cynthia Saylor Professor of Computer Science University of Illinois Urbana-Champaign On Jul 18, 2012, at 10:22 AM, sreeram potluri wrote: > I'd also vote for adding it, to be consistent. > > Thanks, > Sreeram > > On Wed, Jul 18, 2012 at 9:54 AM, Torsten Hoefler <htor(a)illinois.edu> wrote: >> Hi group, >> >> Hubert just brought this up at the ticket. It's a valid point but may be >> a bit late. Unfortunately, we're far away from a quorum at the Forum (we >> have only Sreeram and me in the room). So I am broadcasting the question >> to the mailinglist. >> >> Any opinions? I'd vote to add it also (as part of yesterday's change). >> >> Thanks, >> Torsten >> >> -- >> ### qreharg rug ebs fv crryF ------------- http://www.unixer.de/ ----- >> Torsten Hoefler | Performance Modeling and Simulation Lead >> Blue Waters Directorate | University of Illinois (UIUC) >> 1205 W Clark Street | Urbana, IL, 61801 >> NCSA Building | +01 (217) 244-7736 >> _______________________________________________ >> mpi3-rma mailing list >> mpi3-rma(a)lists.mpi-forum.org >> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma > _______________________________________________ > mpi3-rma mailing list > mpi3-rma(a)lists.mpi-forum.org > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma

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Re: [Mpi3-rma] notes from 5pm Tuesday meeting @ July 2012 Forum
by Jeff Hammond 18 Jul '12

18 Jul '12

has x changed below? { double x = 0.3; x *= 7; x /= 7; } do you really want to add a paragraph on how floating point arithmetic works just so that users understand what you mean by "has not changed"? jeff On Wed, Jul 18, 2012 at 10:25 AM, Underwood, Keith D <keith.d.underwood(a)intel.com> wrote: > Because that would really suck for the user? :-) The == operator is quite sensible from the "has this changed" perspective... And, meaningless mathematically for floating-point > > Keith > >> -----Original Message----- >> From: mpi3-rma-bounces(a)lists.mpi-forum.org [mailto:mpi3-rma- >> bounces(a)lists.mpi-forum.org] On Behalf Of Jeff Hammond >> Sent: Wednesday, July 18, 2012 11:22 AM >> To: MPI 3.0 Remote Memory Access working group >> Subject: Re: [Mpi3-rma] notes from 5pm Tuesday meeting @ July 2012 >> Forum >> >> i meant make the user cast. i think you underestimate how often scientists >> falsely think that == acts on floating point numbers in a mathematically >> sensible way. >> >> On Wed, Jul 18, 2012 at 10:18 AM, Underwood, Keith D >> <keith.d.underwood(a)intel.com> wrote: >> > Yes, the MPI library could certainly make that choice in how it used the >> hardware... >> > >> >> -----Original Message----- >> >> From: mpi3-rma-bounces(a)lists.mpi-forum.org [mailto:mpi3-rma- >> >> bounces(a)lists.mpi-forum.org] On Behalf Of Jeff Hammond >> >> Sent: Wednesday, July 18, 2012 11:09 AM >> >> To: MPI 3.0 Remote Memory Access working group >> >> Subject: Re: [Mpi3-rma] notes from 5pm Tuesday meeting @ July 2012 >> >> Forum >> >> >> >> So your A==B comparison is at the level of bits? Couldn't you just >> >> cast double to long then? >> >> >> >> Jeff >> >> >> >> On Wed, Jul 18, 2012 at 10:03 AM, Underwood, Keith D >> >> <keith.d.underwood(a)intel.com> wrote: >> >> > success=0; >> >> > while (!success) { >> >> > A=B; // B is remote, obtained using RMA >> >> > C=(A*D+E*F) / G; // Everything local, all are doubles >> >> > if (B == A) {B=C; success = 1}; // This is CAS } >> >> > >> >> > And now you have done a relatively complicated thing on B >> >> > atomically, >> >> though you will suffer if there is contention... >> >> > >> >> > Keith >> >> > >> >> >> -----Original Message----- >> >> >> From: mpi3-rma-bounces(a)lists.mpi-forum.org [mailto:mpi3-rma- >> >> >> bounces(a)lists.mpi-forum.org] On Behalf Of Jeff Hammond >> >> >> Sent: Tuesday, July 17, 2012 11:03 PM >> >> >> To: MPI 3.0 Remote Memory Access working group >> >> >> Subject: Re: [Mpi3-rma] notes from 5pm Tuesday meeting @ July 2012 >> >> >> Forum >> >> >> >> >> >> What do you mean by "arbitrary atomics"? Are you proposing to do >> >> >> something evil with bitwise comparison on floating-point numbers >> >> >> to realize something other than the obvious meaning of CAS on a >> >> >> float type? If so, just say it, then do it the right way. >> >> >> >> >> >> We should consider how users will interpret CAS on doubles, for >> >> >> example, and not what some low-level network person can dream up >> >> >> to do with this operation. >> >> >> >> >> >> What architecture implements remote CAS on floating-point types in >> >> >> hardware right now? Who is proposing it? I invoke the standard >> >> >> (and a bit worn out) argument about implementing MPI-3 entirely in >> >> >> hardware and say that unless someone knows how to do CAS for >> >> >> doubles, it cannot be in the standard. >> >> >> >> >> >> And to be perfectly honest, I have utterly no idea what you really >> >> >> mean right now so it would be very helpful if you could be very >> >> >> explicit about what you mean by CAS on floating point types. What >> >> >> measure are you using for comparison? Does this have any reason >> >> >> meaning in the context of floating point arithmetic? >> >> >> >> >> >> Jeff >> >> >> >> >> >> On Tue, Jul 17, 2012 at 9:40 PM, Underwood, Keith D >> >> >> <keith.d.underwood(a)intel.com> wrote: >> >> >> > Floating-point CAS is valid as a way to implement "if this >> >> >> > hasn't changed, >> >> >> put the results of this operation in place". It gives you a >> >> >> (moderately expensive, not very fair) way to build a form of >> >> >> arbitrary >> >> atomics. >> >> >> > >> >> >> > Keith >> >> >> > >> >> >> >> -----Original Message----- >> >> >> >> From: mpi3-rma-bounces(a)lists.mpi-forum.org [mailto:mpi3-rma- >> >> >> >> bounces(a)lists.mpi-forum.org] On Behalf Of Jeff Hammond >> >> >> >> Sent: Tuesday, July 17, 2012 7:26 PM >> >> >> >> To: MPI 3.0 Remote Memory Access working group >> >> >> >> Subject: Re: [Mpi3-rma] notes from 5pm Tuesday meeting @ July >> >> >> >> 2012 Forum >> >> >> >> >> >> >> >> I don't know that floating-point compare is well-defined. You >> >> >> >> really have ask "if abs(x-y)<tolerance" and not "if x==y". >> >> >> >> >> >> >> >> I think only fixed-point types should be valid for CAS. >> >> >> >> >> >> >> >> Jeff >> >> >> >> >> >> >> >> On Tue, Jul 17, 2012 at 6:14 PM, Dave Goodell >> >> >> >> <goodell(a)mcs.anl.gov> >> >> >> wrote: >> >> >> >> > Discussed the complex types in COMPARE_AND_SWAP issue. >> >> "Fortran >> >> >> >> Integer" category is permitted, but "Complex" category is not, >> >> >> >> primarily because of width. Since "Fortran Integer" contains >> >> >> >> wide types, shouldn't we just permit "Complex" and "Floating >> >> >> >> point" as well? Consensus was to stick with the existing text >> >> >> >> which permits only "C integer, Fortran integer, Logical, >> >> >> >> Multi-language types, or >> >> Byte". >> >> >> >> > >> >> >> >> > Group review (esp. Jim & Sreeram): >> >> >> >> > https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/187 >> >> >> >> > >> >> >> >> > incorporate Jim suggested change (Torsten): >> >> >> >> > https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/271 >> >> >> >> > >> >> >> >> > we think we are unaffected, but need a second check (Jim): >> >> >> >> > https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/278 >> >> >> >> > >> >> >> >> > Double-check that C++ is not referenced in the RMA chapter >> >> (Pavan): >> >> >> >> > https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/281 >> >> >> >> > >> >> >> >> > Needs review (Dave): >> >> >> >> > https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/300 >> >> >> >> > >> >> >> >> > Think unaffected, but slim chance of Rput/Rget being affected >> >> (Pavan): >> >> >> >> > https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/317 >> >> >> >> > >> >> >> >> > Need to check implementation of various (4?) "flush is non-local" >> >> >> >> > changes (Dave): >> >> >> >> > https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/270 >> >> >> >> > >> >> >> >> > Need to check disp_unit change (Jim & Sreeram): >> >> >> >> > https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/284 >> >> >> >> > >> >> >> >> > After the above items have all been dealt with, all chapter >> >> >> >> > committee >> >> >> >> members should re-read the whole chapter in the *clean* >> >> >> >> document (the one _without_ the changebars and colored text) to >> >> >> >> look for obvious typos and inconsistencies. >> >> >> >> > >> >> >> >> > -Dave >> >> >> >> > >> >> >> >> > >> >> >> >> > _______________________________________________ >> >> >> >> > mpi3-rma mailing list >> >> >> >> > mpi3-rma(a)lists.mpi-forum.org >> >> >> >> > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> -- >> >> >> >> Jeff Hammond >> >> >> >> Argonne Leadership Computing Facility University of Chicago >> >> >> >> Computation Institute jhammond(a)alcf.anl.gov / (630) >> >> >> >> 252-5381 http://www.linkedin.com/in/jeffhammond >> >> >> >> https://wiki.alcf.anl.gov/parts/index.php/User:Jhammond >> >> >> >> >> >> >> >> _______________________________________________ >> >> >> >> mpi3-rma mailing list >> >> >> >> mpi3-rma(a)lists.mpi-forum.org >> >> >> >> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma >> >> >> > >> >> >> > _______________________________________________ >> >> >> > mpi3-rma mailing list >> >> >> > mpi3-rma(a)lists.mpi-forum.org >> >> >> > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma >> >> >> >> >> >> >> >> >> >> >> >> -- >> >> >> Jeff Hammond >> >> >> Argonne Leadership Computing Facility University of Chicago >> >> >> Computation Institute jhammond(a)alcf.anl.gov / (630) >> >> >> 252-5381 http://www.linkedin.com/in/jeffhammond >> >> >> https://wiki.alcf.anl.gov/parts/index.php/User:Jhammond >> >> >> _______________________________________________ >> >> >> mpi3-rma mailing list >> >> >> mpi3-rma(a)lists.mpi-forum.org >> >> >> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma >> >> > >> >> > _______________________________________________ >> >> > mpi3-rma mailing list >> >> > mpi3-rma(a)lists.mpi-forum.org >> >> > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma >> >> >> >> >> >> >> >> -- >> >> Jeff Hammond >> >> Argonne Leadership Computing Facility University of Chicago >> >> Computation Institute jhammond(a)alcf.anl.gov / (630) >> >> 252-5381 http://www.linkedin.com/in/jeffhammond >> >> https://wiki.alcf.anl.gov/parts/index.php/User:Jhammond >> >> _______________________________________________ >> >> mpi3-rma mailing list >> >> mpi3-rma(a)lists.mpi-forum.org >> >> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma >> > >> > _______________________________________________ >> > mpi3-rma mailing list >> > mpi3-rma(a)lists.mpi-forum.org >> > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma >> >> >> >> -- >> Jeff Hammond >> Argonne Leadership Computing Facility >> University of Chicago Computation Institute jhammond(a)alcf.anl.gov / (630) >> 252-5381 http://www.linkedin.com/in/jeffhammond >> https://wiki.alcf.anl.gov/parts/index.php/User:Jhammond >> _______________________________________________ >> mpi3-rma mailing list >> mpi3-rma(a)lists.mpi-forum.org >> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma > > _______________________________________________ > mpi3-rma mailing list > mpi3-rma(a)lists.mpi-forum.org > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma -- Jeff Hammond Argonne Leadership Computing Facility University of Chicago Computation Institute jhammond(a)alcf.anl.gov / (630) 252-5381 http://www.linkedin.com/in/jeffhammond https://wiki.alcf.anl.gov/parts/index.php/User:Jhammond

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Re: [Mpi3-rma] notes from 5pm Tuesday meeting @ July 2012 Forum
by Underwood, Keith D 18 Jul '12

18 Jul '12

Because that would really suck for the user? :-) The == operator is quite sensible from the "has this changed" perspective... And, meaningless mathematically for floating-point Keith > -----Original Message----- > From: mpi3-rma-bounces(a)lists.mpi-forum.org [mailto:mpi3-rma- > bounces(a)lists.mpi-forum.org] On Behalf Of Jeff Hammond > Sent: Wednesday, July 18, 2012 11:22 AM > To: MPI 3.0 Remote Memory Access working group > Subject: Re: [Mpi3-rma] notes from 5pm Tuesday meeting @ July 2012 > Forum > > i meant make the user cast. i think you underestimate how often scientists > falsely think that == acts on floating point numbers in a mathematically > sensible way. > > On Wed, Jul 18, 2012 at 10:18 AM, Underwood, Keith D > <keith.d.underwood(a)intel.com> wrote: > > Yes, the MPI library could certainly make that choice in how it used the > hardware... > > > >> -----Original Message----- > >> From: mpi3-rma-bounces(a)lists.mpi-forum.org [mailto:mpi3-rma- > >> bounces(a)lists.mpi-forum.org] On Behalf Of Jeff Hammond > >> Sent: Wednesday, July 18, 2012 11:09 AM > >> To: MPI 3.0 Remote Memory Access working group > >> Subject: Re: [Mpi3-rma] notes from 5pm Tuesday meeting @ July 2012 > >> Forum > >> > >> So your A==B comparison is at the level of bits? Couldn't you just > >> cast double to long then? > >> > >> Jeff > >> > >> On Wed, Jul 18, 2012 at 10:03 AM, Underwood, Keith D > >> <keith.d.underwood(a)intel.com> wrote: > >> > success=0; > >> > while (!success) { > >> > A=B; // B is remote, obtained using RMA > >> > C=(A*D+E*F) / G; // Everything local, all are doubles > >> > if (B == A) {B=C; success = 1}; // This is CAS } > >> > > >> > And now you have done a relatively complicated thing on B > >> > atomically, > >> though you will suffer if there is contention... > >> > > >> > Keith > >> > > >> >> -----Original Message----- > >> >> From: mpi3-rma-bounces(a)lists.mpi-forum.org [mailto:mpi3-rma- > >> >> bounces(a)lists.mpi-forum.org] On Behalf Of Jeff Hammond > >> >> Sent: Tuesday, July 17, 2012 11:03 PM > >> >> To: MPI 3.0 Remote Memory Access working group > >> >> Subject: Re: [Mpi3-rma] notes from 5pm Tuesday meeting @ July 2012 > >> >> Forum > >> >> > >> >> What do you mean by "arbitrary atomics"? Are you proposing to do > >> >> something evil with bitwise comparison on floating-point numbers > >> >> to realize something other than the obvious meaning of CAS on a > >> >> float type? If so, just say it, then do it the right way. > >> >> > >> >> We should consider how users will interpret CAS on doubles, for > >> >> example, and not what some low-level network person can dream up > >> >> to do with this operation. > >> >> > >> >> What architecture implements remote CAS on floating-point types in > >> >> hardware right now? Who is proposing it? I invoke the standard > >> >> (and a bit worn out) argument about implementing MPI-3 entirely in > >> >> hardware and say that unless someone knows how to do CAS for > >> >> doubles, it cannot be in the standard. > >> >> > >> >> And to be perfectly honest, I have utterly no idea what you really > >> >> mean right now so it would be very helpful if you could be very > >> >> explicit about what you mean by CAS on floating point types. What > >> >> measure are you using for comparison? Does this have any reason > >> >> meaning in the context of floating point arithmetic? > >> >> > >> >> Jeff > >> >> > >> >> On Tue, Jul 17, 2012 at 9:40 PM, Underwood, Keith D > >> >> <keith.d.underwood(a)intel.com> wrote: > >> >> > Floating-point CAS is valid as a way to implement "if this > >> >> > hasn't changed, > >> >> put the results of this operation in place". It gives you a > >> >> (moderately expensive, not very fair) way to build a form of > >> >> arbitrary > >> atomics. > >> >> > > >> >> > Keith > >> >> > > >> >> >> -----Original Message----- > >> >> >> From: mpi3-rma-bounces(a)lists.mpi-forum.org [mailto:mpi3-rma- > >> >> >> bounces(a)lists.mpi-forum.org] On Behalf Of Jeff Hammond > >> >> >> Sent: Tuesday, July 17, 2012 7:26 PM > >> >> >> To: MPI 3.0 Remote Memory Access working group > >> >> >> Subject: Re: [Mpi3-rma] notes from 5pm Tuesday meeting @ July > >> >> >> 2012 Forum > >> >> >> > >> >> >> I don't know that floating-point compare is well-defined. You > >> >> >> really have ask "if abs(x-y)<tolerance" and not "if x==y". > >> >> >> > >> >> >> I think only fixed-point types should be valid for CAS. > >> >> >> > >> >> >> Jeff > >> >> >> > >> >> >> On Tue, Jul 17, 2012 at 6:14 PM, Dave Goodell > >> >> >> <goodell(a)mcs.anl.gov> > >> >> wrote: > >> >> >> > Discussed the complex types in COMPARE_AND_SWAP issue. > >> "Fortran > >> >> >> Integer" category is permitted, but "Complex" category is not, > >> >> >> primarily because of width. Since "Fortran Integer" contains > >> >> >> wide types, shouldn't we just permit "Complex" and "Floating > >> >> >> point" as well? Consensus was to stick with the existing text > >> >> >> which permits only "C integer, Fortran integer, Logical, > >> >> >> Multi-language types, or > >> Byte". > >> >> >> > > >> >> >> > Group review (esp. Jim & Sreeram): > >> >> >> > https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/187 > >> >> >> > > >> >> >> > incorporate Jim suggested change (Torsten): > >> >> >> > https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/271 > >> >> >> > > >> >> >> > we think we are unaffected, but need a second check (Jim): > >> >> >> > https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/278 > >> >> >> > > >> >> >> > Double-check that C++ is not referenced in the RMA chapter > >> (Pavan): > >> >> >> > https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/281 > >> >> >> > > >> >> >> > Needs review (Dave): > >> >> >> > https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/300 > >> >> >> > > >> >> >> > Think unaffected, but slim chance of Rput/Rget being affected > >> (Pavan): > >> >> >> > https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/317 > >> >> >> > > >> >> >> > Need to check implementation of various (4?) "flush is non-local" > >> >> >> > changes (Dave): > >> >> >> > https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/270 > >> >> >> > > >> >> >> > Need to check disp_unit change (Jim & Sreeram): > >> >> >> > https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/284 > >> >> >> > > >> >> >> > After the above items have all been dealt with, all chapter > >> >> >> > committee > >> >> >> members should re-read the whole chapter in the *clean* > >> >> >> document (the one _without_ the changebars and colored text) to > >> >> >> look for obvious typos and inconsistencies. > >> >> >> > > >> >> >> > -Dave > >> >> >> > > >> >> >> > > >> >> >> > _______________________________________________ > >> >> >> > mpi3-rma mailing list > >> >> >> > mpi3-rma(a)lists.mpi-forum.org > >> >> >> > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma > >> >> >> > >> >> >> > >> >> >> > >> >> >> -- > >> >> >> Jeff Hammond > >> >> >> Argonne Leadership Computing Facility University of Chicago > >> >> >> Computation Institute jhammond(a)alcf.anl.gov / (630) > >> >> >> 252-5381 http://www.linkedin.com/in/jeffhammond > >> >> >> https://wiki.alcf.anl.gov/parts/index.php/User:Jhammond > >> >> >> > >> >> >> _______________________________________________ > >> >> >> mpi3-rma mailing list > >> >> >> mpi3-rma(a)lists.mpi-forum.org > >> >> >> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma > >> >> > > >> >> > _______________________________________________ > >> >> > mpi3-rma mailing list > >> >> > mpi3-rma(a)lists.mpi-forum.org > >> >> > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma > >> >> > >> >> > >> >> > >> >> -- > >> >> Jeff Hammond > >> >> Argonne Leadership Computing Facility University of Chicago > >> >> Computation Institute jhammond(a)alcf.anl.gov / (630) > >> >> 252-5381 http://www.linkedin.com/in/jeffhammond > >> >> https://wiki.alcf.anl.gov/parts/index.php/User:Jhammond > >> >> _______________________________________________ > >> >> mpi3-rma mailing list > >> >> mpi3-rma(a)lists.mpi-forum.org > >> >> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma > >> > > >> > _______________________________________________ > >> > mpi3-rma mailing list > >> > mpi3-rma(a)lists.mpi-forum.org > >> > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma > >> > >> > >> > >> -- > >> Jeff Hammond > >> Argonne Leadership Computing Facility University of Chicago > >> Computation Institute jhammond(a)alcf.anl.gov / (630) > >> 252-5381 http://www.linkedin.com/in/jeffhammond > >> https://wiki.alcf.anl.gov/parts/index.php/User:Jhammond > >> _______________________________________________ > >> mpi3-rma mailing list > >> mpi3-rma(a)lists.mpi-forum.org > >> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma > > > > _______________________________________________ > > mpi3-rma mailing list > > mpi3-rma(a)lists.mpi-forum.org > > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma > > > > -- > Jeff Hammond > Argonne Leadership Computing Facility > University of Chicago Computation Institute jhammond(a)alcf.anl.gov / (630) > 252-5381 http://www.linkedin.com/in/jeffhammond > https://wiki.alcf.anl.gov/parts/index.php/User:Jhammond > _______________________________________________ > mpi3-rma mailing list > mpi3-rma(a)lists.mpi-forum.org > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma

1 0

Re: [Mpi3-rma] Disp_unit in allocate_shared should be returned by win_shared_query?
by sreeram potluri 18 Jul '12

18 Jul '12

I'd also vote for adding it, to be consistent. Thanks, Sreeram On Wed, Jul 18, 2012 at 9:54 AM, Torsten Hoefler <htor(a)illinois.edu> wrote: > Hi group, > > Hubert just brought this up at the ticket. It's a valid point but may be > a bit late. Unfortunately, we're far away from a quorum at the Forum (we > have only Sreeram and me in the room). So I am broadcasting the question > to the mailinglist. > > Any opinions? I'd vote to add it also (as part of yesterday's change). > > Thanks, > Torsten > > -- > ### qreharg rug ebs fv crryF ------------- http://www.unixer.de/ ----- > Torsten Hoefler | Performance Modeling and Simulation Lead > Blue Waters Directorate | University of Illinois (UIUC) > 1205 W Clark Street | Urbana, IL, 61801 > NCSA Building | +01 (217) 244-7736 > _______________________________________________ > mpi3-rma mailing list > mpi3-rma(a)lists.mpi-forum.org > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma

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Re: [Mpi3-rma] notes from 5pm Tuesday meeting @ July 2012 Forum
by Jeff Hammond 18 Jul '12

18 Jul '12

i meant make the user cast. i think you underestimate how often scientists falsely think that == acts on floating point numbers in a mathematically sensible way. On Wed, Jul 18, 2012 at 10:18 AM, Underwood, Keith D <keith.d.underwood(a)intel.com> wrote: > Yes, the MPI library could certainly make that choice in how it used the hardware... > >> -----Original Message----- >> From: mpi3-rma-bounces(a)lists.mpi-forum.org [mailto:mpi3-rma- >> bounces(a)lists.mpi-forum.org] On Behalf Of Jeff Hammond >> Sent: Wednesday, July 18, 2012 11:09 AM >> To: MPI 3.0 Remote Memory Access working group >> Subject: Re: [Mpi3-rma] notes from 5pm Tuesday meeting @ July 2012 >> Forum >> >> So your A==B comparison is at the level of bits? Couldn't you just cast double >> to long then? >> >> Jeff >> >> On Wed, Jul 18, 2012 at 10:03 AM, Underwood, Keith D >> <keith.d.underwood(a)intel.com> wrote: >> > success=0; >> > while (!success) { >> > A=B; // B is remote, obtained using RMA >> > C=(A*D+E*F) / G; // Everything local, all are doubles >> > if (B == A) {B=C; success = 1}; // This is CAS } >> > >> > And now you have done a relatively complicated thing on B atomically, >> though you will suffer if there is contention... >> > >> > Keith >> > >> >> -----Original Message----- >> >> From: mpi3-rma-bounces(a)lists.mpi-forum.org [mailto:mpi3-rma- >> >> bounces(a)lists.mpi-forum.org] On Behalf Of Jeff Hammond >> >> Sent: Tuesday, July 17, 2012 11:03 PM >> >> To: MPI 3.0 Remote Memory Access working group >> >> Subject: Re: [Mpi3-rma] notes from 5pm Tuesday meeting @ July 2012 >> >> Forum >> >> >> >> What do you mean by "arbitrary atomics"? Are you proposing to do >> >> something evil with bitwise comparison on floating-point numbers to >> >> realize something other than the obvious meaning of CAS on a float >> >> type? If so, just say it, then do it the right way. >> >> >> >> We should consider how users will interpret CAS on doubles, for >> >> example, and not what some low-level network person can dream up to >> >> do with this operation. >> >> >> >> What architecture implements remote CAS on floating-point types in >> >> hardware right now? Who is proposing it? I invoke the standard (and >> >> a bit worn out) argument about implementing MPI-3 entirely in >> >> hardware and say that unless someone knows how to do CAS for doubles, >> >> it cannot be in the standard. >> >> >> >> And to be perfectly honest, I have utterly no idea what you really >> >> mean right now so it would be very helpful if you could be very >> >> explicit about what you mean by CAS on floating point types. What >> >> measure are you using for comparison? Does this have any reason >> >> meaning in the context of floating point arithmetic? >> >> >> >> Jeff >> >> >> >> On Tue, Jul 17, 2012 at 9:40 PM, Underwood, Keith D >> >> <keith.d.underwood(a)intel.com> wrote: >> >> > Floating-point CAS is valid as a way to implement "if this hasn't >> >> > changed, >> >> put the results of this operation in place". It gives you a >> >> (moderately expensive, not very fair) way to build a form of arbitrary >> atomics. >> >> > >> >> > Keith >> >> > >> >> >> -----Original Message----- >> >> >> From: mpi3-rma-bounces(a)lists.mpi-forum.org [mailto:mpi3-rma- >> >> >> bounces(a)lists.mpi-forum.org] On Behalf Of Jeff Hammond >> >> >> Sent: Tuesday, July 17, 2012 7:26 PM >> >> >> To: MPI 3.0 Remote Memory Access working group >> >> >> Subject: Re: [Mpi3-rma] notes from 5pm Tuesday meeting @ July 2012 >> >> >> Forum >> >> >> >> >> >> I don't know that floating-point compare is well-defined. You >> >> >> really have ask "if abs(x-y)<tolerance" and not "if x==y". >> >> >> >> >> >> I think only fixed-point types should be valid for CAS. >> >> >> >> >> >> Jeff >> >> >> >> >> >> On Tue, Jul 17, 2012 at 6:14 PM, Dave Goodell >> >> >> <goodell(a)mcs.anl.gov> >> >> wrote: >> >> >> > Discussed the complex types in COMPARE_AND_SWAP issue. >> "Fortran >> >> >> Integer" category is permitted, but "Complex" category is not, >> >> >> primarily because of width. Since "Fortran Integer" contains wide >> >> >> types, shouldn't we just permit "Complex" and "Floating point" as >> >> >> well? Consensus was to stick with the existing text which permits >> >> >> only "C integer, Fortran integer, Logical, Multi-language types, or >> Byte". >> >> >> > >> >> >> > Group review (esp. Jim & Sreeram): >> >> >> > https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/187 >> >> >> > >> >> >> > incorporate Jim suggested change (Torsten): >> >> >> > https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/271 >> >> >> > >> >> >> > we think we are unaffected, but need a second check (Jim): >> >> >> > https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/278 >> >> >> > >> >> >> > Double-check that C++ is not referenced in the RMA chapter >> (Pavan): >> >> >> > https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/281 >> >> >> > >> >> >> > Needs review (Dave): >> >> >> > https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/300 >> >> >> > >> >> >> > Think unaffected, but slim chance of Rput/Rget being affected >> (Pavan): >> >> >> > https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/317 >> >> >> > >> >> >> > Need to check implementation of various (4?) "flush is non-local" >> >> >> > changes (Dave): >> >> >> > https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/270 >> >> >> > >> >> >> > Need to check disp_unit change (Jim & Sreeram): >> >> >> > https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/284 >> >> >> > >> >> >> > After the above items have all been dealt with, all chapter >> >> >> > committee >> >> >> members should re-read the whole chapter in the *clean* document >> >> >> (the one _without_ the changebars and colored text) to look for >> >> >> obvious typos and inconsistencies. >> >> >> > >> >> >> > -Dave >> >> >> > >> >> >> > >> >> >> > _______________________________________________ >> >> >> > mpi3-rma mailing list >> >> >> > mpi3-rma(a)lists.mpi-forum.org >> >> >> > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma >> >> >> >> >> >> >> >> >> >> >> >> -- >> >> >> Jeff Hammond >> >> >> Argonne Leadership Computing Facility University of Chicago >> >> >> Computation Institute jhammond(a)alcf.anl.gov / (630) >> >> >> 252-5381 http://www.linkedin.com/in/jeffhammond >> >> >> https://wiki.alcf.anl.gov/parts/index.php/User:Jhammond >> >> >> >> >> >> _______________________________________________ >> >> >> mpi3-rma mailing list >> >> >> mpi3-rma(a)lists.mpi-forum.org >> >> >> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma >> >> > >> >> > _______________________________________________ >> >> > mpi3-rma mailing list >> >> > mpi3-rma(a)lists.mpi-forum.org >> >> > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma >> >> >> >> >> >> >> >> -- >> >> Jeff Hammond >> >> Argonne Leadership Computing Facility University of Chicago >> >> Computation Institute jhammond(a)alcf.anl.gov / (630) >> >> 252-5381 http://www.linkedin.com/in/jeffhammond >> >> https://wiki.alcf.anl.gov/parts/index.php/User:Jhammond >> >> _______________________________________________ >> >> mpi3-rma mailing list >> >> mpi3-rma(a)lists.mpi-forum.org >> >> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma >> > >> > _______________________________________________ >> > mpi3-rma mailing list >> > mpi3-rma(a)lists.mpi-forum.org >> > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma >> >> >> >> -- >> Jeff Hammond >> Argonne Leadership Computing Facility >> University of Chicago Computation Institute jhammond(a)alcf.anl.gov / (630) >> 252-5381 http://www.linkedin.com/in/jeffhammond >> https://wiki.alcf.anl.gov/parts/index.php/User:Jhammond >> _______________________________________________ >> mpi3-rma mailing list >> mpi3-rma(a)lists.mpi-forum.org >> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma > > _______________________________________________ > mpi3-rma mailing list > mpi3-rma(a)lists.mpi-forum.org > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma -- Jeff Hammond Argonne Leadership Computing Facility University of Chicago Computation Institute jhammond(a)alcf.anl.gov / (630) 252-5381 http://www.linkedin.com/in/jeffhammond https://wiki.alcf.anl.gov/parts/index.php/User:Jhammond

1 0

Re: [Mpi3-rma] notes from 5pm Tuesday meeting @ July 2012 Forum
by Underwood, Keith D 18 Jul '12

18 Jul '12

Yes, the MPI library could certainly make that choice in how it used the hardware... > -----Original Message----- > From: mpi3-rma-bounces(a)lists.mpi-forum.org [mailto:mpi3-rma- > bounces(a)lists.mpi-forum.org] On Behalf Of Jeff Hammond > Sent: Wednesday, July 18, 2012 11:09 AM > To: MPI 3.0 Remote Memory Access working group > Subject: Re: [Mpi3-rma] notes from 5pm Tuesday meeting @ July 2012 > Forum > > So your A==B comparison is at the level of bits? Couldn't you just cast double > to long then? > > Jeff > > On Wed, Jul 18, 2012 at 10:03 AM, Underwood, Keith D > <keith.d.underwood(a)intel.com> wrote: > > success=0; > > while (!success) { > > A=B; // B is remote, obtained using RMA > > C=(A*D+E*F) / G; // Everything local, all are doubles > > if (B == A) {B=C; success = 1}; // This is CAS } > > > > And now you have done a relatively complicated thing on B atomically, > though you will suffer if there is contention... > > > > Keith > > > >> -----Original Message----- > >> From: mpi3-rma-bounces(a)lists.mpi-forum.org [mailto:mpi3-rma- > >> bounces(a)lists.mpi-forum.org] On Behalf Of Jeff Hammond > >> Sent: Tuesday, July 17, 2012 11:03 PM > >> To: MPI 3.0 Remote Memory Access working group > >> Subject: Re: [Mpi3-rma] notes from 5pm Tuesday meeting @ July 2012 > >> Forum > >> > >> What do you mean by "arbitrary atomics"? Are you proposing to do > >> something evil with bitwise comparison on floating-point numbers to > >> realize something other than the obvious meaning of CAS on a float > >> type? If so, just say it, then do it the right way. > >> > >> We should consider how users will interpret CAS on doubles, for > >> example, and not what some low-level network person can dream up to > >> do with this operation. > >> > >> What architecture implements remote CAS on floating-point types in > >> hardware right now? Who is proposing it? I invoke the standard (and > >> a bit worn out) argument about implementing MPI-3 entirely in > >> hardware and say that unless someone knows how to do CAS for doubles, > >> it cannot be in the standard. > >> > >> And to be perfectly honest, I have utterly no idea what you really > >> mean right now so it would be very helpful if you could be very > >> explicit about what you mean by CAS on floating point types. What > >> measure are you using for comparison? Does this have any reason > >> meaning in the context of floating point arithmetic? > >> > >> Jeff > >> > >> On Tue, Jul 17, 2012 at 9:40 PM, Underwood, Keith D > >> <keith.d.underwood(a)intel.com> wrote: > >> > Floating-point CAS is valid as a way to implement "if this hasn't > >> > changed, > >> put the results of this operation in place". It gives you a > >> (moderately expensive, not very fair) way to build a form of arbitrary > atomics. > >> > > >> > Keith > >> > > >> >> -----Original Message----- > >> >> From: mpi3-rma-bounces(a)lists.mpi-forum.org [mailto:mpi3-rma- > >> >> bounces(a)lists.mpi-forum.org] On Behalf Of Jeff Hammond > >> >> Sent: Tuesday, July 17, 2012 7:26 PM > >> >> To: MPI 3.0 Remote Memory Access working group > >> >> Subject: Re: [Mpi3-rma] notes from 5pm Tuesday meeting @ July 2012 > >> >> Forum > >> >> > >> >> I don't know that floating-point compare is well-defined. You > >> >> really have ask "if abs(x-y)<tolerance" and not "if x==y". > >> >> > >> >> I think only fixed-point types should be valid for CAS. > >> >> > >> >> Jeff > >> >> > >> >> On Tue, Jul 17, 2012 at 6:14 PM, Dave Goodell > >> >> <goodell(a)mcs.anl.gov> > >> wrote: > >> >> > Discussed the complex types in COMPARE_AND_SWAP issue. > "Fortran > >> >> Integer" category is permitted, but "Complex" category is not, > >> >> primarily because of width. Since "Fortran Integer" contains wide > >> >> types, shouldn't we just permit "Complex" and "Floating point" as > >> >> well? Consensus was to stick with the existing text which permits > >> >> only "C integer, Fortran integer, Logical, Multi-language types, or > Byte". > >> >> > > >> >> > Group review (esp. Jim & Sreeram): > >> >> > https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/187 > >> >> > > >> >> > incorporate Jim suggested change (Torsten): > >> >> > https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/271 > >> >> > > >> >> > we think we are unaffected, but need a second check (Jim): > >> >> > https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/278 > >> >> > > >> >> > Double-check that C++ is not referenced in the RMA chapter > (Pavan): > >> >> > https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/281 > >> >> > > >> >> > Needs review (Dave): > >> >> > https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/300 > >> >> > > >> >> > Think unaffected, but slim chance of Rput/Rget being affected > (Pavan): > >> >> > https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/317 > >> >> > > >> >> > Need to check implementation of various (4?) "flush is non-local" > >> >> > changes (Dave): > >> >> > https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/270 > >> >> > > >> >> > Need to check disp_unit change (Jim & Sreeram): > >> >> > https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/284 > >> >> > > >> >> > After the above items have all been dealt with, all chapter > >> >> > committee > >> >> members should re-read the whole chapter in the *clean* document > >> >> (the one _without_ the changebars and colored text) to look for > >> >> obvious typos and inconsistencies. > >> >> > > >> >> > -Dave > >> >> > > >> >> > > >> >> > _______________________________________________ > >> >> > mpi3-rma mailing list > >> >> > mpi3-rma(a)lists.mpi-forum.org > >> >> > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma > >> >> > >> >> > >> >> > >> >> -- > >> >> Jeff Hammond > >> >> Argonne Leadership Computing Facility University of Chicago > >> >> Computation Institute jhammond(a)alcf.anl.gov / (630) > >> >> 252-5381 http://www.linkedin.com/in/jeffhammond > >> >> https://wiki.alcf.anl.gov/parts/index.php/User:Jhammond > >> >> > >> >> _______________________________________________ > >> >> mpi3-rma mailing list > >> >> mpi3-rma(a)lists.mpi-forum.org > >> >> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma > >> > > >> > _______________________________________________ > >> > mpi3-rma mailing list > >> > mpi3-rma(a)lists.mpi-forum.org > >> > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma > >> > >> > >> > >> -- > >> Jeff Hammond > >> Argonne Leadership Computing Facility University of Chicago > >> Computation Institute jhammond(a)alcf.anl.gov / (630) > >> 252-5381 http://www.linkedin.com/in/jeffhammond > >> https://wiki.alcf.anl.gov/parts/index.php/User:Jhammond > >> _______________________________________________ > >> mpi3-rma mailing list > >> mpi3-rma(a)lists.mpi-forum.org > >> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma > > > > _______________________________________________ > > mpi3-rma mailing list > > mpi3-rma(a)lists.mpi-forum.org > > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma > > > > -- > Jeff Hammond > Argonne Leadership Computing Facility > University of Chicago Computation Institute jhammond(a)alcf.anl.gov / (630) > 252-5381 http://www.linkedin.com/in/jeffhammond > https://wiki.alcf.anl.gov/parts/index.php/User:Jhammond > _______________________________________________ > mpi3-rma mailing list > mpi3-rma(a)lists.mpi-forum.org > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma

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Re: [Mpi3-rma] Disp_unit in allocate_shared should be returned by win_shared_query?
by Torsten Hoefler 18 Jul '12

18 Jul '12

On Wed, Jul 18, 2012 at 10:05:59AM -0500, Jeff Hammond wrote: > can you elaborate? It's rather simple, the parameter is missing. We added it to the creation routine yesterday. > why does one want this? Consistency. > to figure out what atomicity should be used in load-store access? No > what's the harm in adding it? Nothing, just a change rather late in the process. It would be consistent Best, Torsten -- ### qreharg rug ebs fv crryF ------------- http://www.unixer.de/ ----- Torsten Hoefler | Performance Modeling and Simulation Lead Blue Waters Directorate | University of Illinois (UIUC) 1205 W Clark Street | Urbana, IL, 61801 NCSA Building | +01 (217) 244-7736

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