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

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

18 Jul '12

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

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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

can you elaborate? why does one want this? to figure out what atomicity should be used in load-store access? what's the harm in adding it? thanks. jeff 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 -- 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

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

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

18 Jul '12

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

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Re: [Mpi3-rma] notes from 5pm Tuesday meeting @ July 2012 Forum
by Torsten Hoefler 17 Jul '12

17 Jul '12

Thanks! I forgot this additional interface. It's added now, also see ticket #284. Torsten On Tue, Jul 17, 2012 at 09:38:08PM -0500, sreeram potluri wrote: > > Need to check disp_unit change (Jim & Sreeram): https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/284 > > disp_unit seems to be missing at the following locations > > Page 409 Line 36 and Line 39 > SUBROUTINE MPI_WIN_ALLOCATE_SHARED_CPTR(SIZE, INFO, COMM, BASEPTR, & > > > Group review (esp. Jim & Sreeram): https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/187 > > Reviewed and looks fine. > > Thanks > Sreeram Potluri > > 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 > > _______________________________________________ > 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/ ----- "I would rather have today's algorithms on yesterday's computers than vice versa." - Toint (contemporary)

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Re: [Mpi3-rma] notes from 5pm Tuesday meeting @ July 2012 Forum
by Jeff Hammond 17 Jul '12

17 Jul '12

And note that I strongly agree with the existing consensus "to stick with the existing text which permits only 'C integer, Fortran integer, Logical, Multi-language types, or Byte'." Floating-point atomics should be a separate ticket since they are new semantics that I don't believe that anyone has thought about properly yet. Someone should think hard about what they mean and try to get this feature in MPI-Next. Jeff On Tue, Jul 17, 2012 at 10:03 PM, Jeff Hammond <jhammond(a)alcf.anl.gov> wrote: > 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 -- 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 Jeff Hammond 17 Jul '12

17 Jul '12

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

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Re: [Mpi3-rma] notes from 5pm Tuesday meeting @ July 2012 Forum
by Underwood, Keith D 17 Jul '12

17 Jul '12

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

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Re: [Mpi3-rma] notes from 5pm Tuesday meeting @ July 2012 Forum
by sreeram potluri 17 Jul '12

17 Jul '12

> Need to check disp_unit change (Jim & Sreeram): https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/284 disp_unit seems to be missing at the following locations Page 409 Line 36 and Line 39 SUBROUTINE MPI_WIN_ALLOCATE_SHARED_CPTR(SIZE, INFO, COMM, BASEPTR, & > Group review (esp. Jim & Sreeram): https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/187 Reviewed and looks fine. Thanks Sreeram Potluri 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

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Re: [Mpi3-rma] notes from 5pm Tuesday meeting @ July 2012 Forum
by Dave Goodell 17 Jul '12

17 Jul '12

On Jul 17, 2012, at 6:14 PM CDT, Dave Goodell wrote: > Needs review (Dave): https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/300 Done, everything OK in the clean PDF that Torsten previously sent out. > Need to check implementation of various (4?) "flush is non-local" changes (Dave): https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/270 Done. Everything OK. -Dave

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