March 2014 - mpiwg-rma - mailman3.cels.anl.gov

Re: [mpiwg-rma] same_op_no_op
by maik peterson 13 Mar '14

13 Mar '14

do you really believe users are reading specs ? noone cares... 2014-03-13 17:48 GMT+01:00 Jeff Hammond <jeff.science(a)gmail.com>: > It is extremely difficult to see that this is what the MPI-3 standard says. > > First we have this: > > "The outcome of concurrent accumulate operations to the same location > with the same predefined datatype is as if the accumulates were done > at that location in some serial order. Additional restrictions on the > operation apply; see the info key accumulate_ops in Section 11.2.1. > Concurrent accumulate operations with different origin and target > pairs are not ordered. Thus, there is no guarantee that the entire > call to an accumulate operation is executed atomically. The effect of > this lack of atomicity is limited: The previous correctness conditions > imply that a location updated by a call to an accumulate operation > cannot be accessed by a load or an RMA call other than accumulate > until the accumulate operation has completed (at the target). > Different interleavings can lead to different results only to the > extent that computer arithmetics are not truly associative or > commutative. The outcome of accumulate operations with overlapping > types of different sizes or target displacements is undefined." > [11.7.1 Atomicity] > > Then we have this: > > "accumulate_ops -- if set to same_op, the implementation will assume > that all concurrent accumulate calls to the same target address will > use the same operation. If set to same_op_no_op, then the > implementation will assume that all concurrent accumulate calls to the > same target address will use the same operation or MPI_NO_OP. This can > eliminate the need to protect access for certain operation types where > the hardware can guarantee atomicity. The default is same_op_no_op." > [11.2.1 Window Creation] > > I was not aware that the definition of info keys was normative, given > that implementations are free to ignore them. Even if info key text > is normative, one has to infer from the fact that same_op_no_op is the > default info behavior - and thus RMA semantic - that accumulate > atomicity is restricted to the case where one uses the same op or noop > but not replace. > > The MPI-2.2 spec is unambiguous because it explicitly requires the > same operation in 11.7.1 Atomicity. This text was removed in MPI-3.0 > in favor of the info key text. > > Best, > > Jeff > > On Tue, Mar 11, 2014 at 12:04 AM, Balaji, Pavan <balaji(a)anl.gov> wrote: > > > > MPI-2 defines atomicity only for the same operation, not any operation > for MPI_ACCUMULATE. > > > > -- Pavan > > > > On Mar 10, 2014, at 11:22 PM, Jeff Hammond <jeff.science(a)gmail.com> > wrote: > > > >> So MPI-2 denied compatibility between replace and not-replace? > >> > >> Jeff > >> > >> Sent from my iPhone > >> > >>> On Mar 11, 2014, at 12:06 AM, "Balaji, Pavan" <balaji(a)anl.gov> wrote: > >>> > >>> > >>> It doesn't break backward compatibility. The info argument is still > useful when you don't want to use replace. I don't see anything wrong with > it. > >>> > >>>> On Mar 10, 2014, at 11:01 PM, Jeff Hammond <jeff.science(a)gmail.com> > wrote: > >>>> > >>>> Does this or does this not break BW compatibility w.r.t. MPI-2.2 and > >>>> did we do it intentionally? Unless we did so intentionally and > >>>> explicitly, I will argue that the WG screwed up and the info key+val > >>>> is invalid. > >>>> > >>>> Jeff > >>>> > >>>>> On Mon, Mar 10, 2014 at 11:03 PM, Balaji, Pavan <balaji(a)anl.gov> > wrote: > >>>>> > >>>>> If a hardware can implement MPI_SUM, it should be able to implement > MPI_SUM with 0 as well. > >>>>> > >>>>> But that's not a generic solution. > >>>>> > >>>>> Jeff: at some point you were planning to bring in a ticket which > does more combinations of operations than just same_op and no_op. Maybe > it's worthwhile bringing that up again? > >>>>> > >>>>> -- Pavan > >>>>> > >>>>>> On Mar 10, 2014, at 9:26 PM, Jim Dinan <james.dinan(a)gmail.com> > wrote: > >>>>>> > >>>>>> Maybe there's a loophole that I'm forgetting? > >>>>>> > >>>>>> > >>>>>> On Mon, Mar 10, 2014 at 9:43 PM, Jeff Hammond < > jeff.science(a)gmail.com> wrote: > >>>>>> How the hell can I do GA or SHMEM then? Roll my own mutexes and > commit perf-suicide? > >>>>>> > >>>>>> Jeff > >>>>>> > >>>>>> Sent from my iPhone > >>>>>> > >>>>>>> On Mar 10, 2014, at 8:32 PM, Jim Dinan <james.dinan(a)gmail.com> > wrote: > >>>>>>> > >>>>>>> You can't use replace and sum concurrently at a given target > address. > >>>>>>> > >>>>>>> ~Jim. > >>>>>>> > >>>>>>> On Mon, Mar 10, 2014 at 4:30 PM, Jeff Hammond < > jeff.science(a)gmail.com> wrote: > >>>>>>> Given the following, how do I use MPI_NO_OP, MPI_REPLACE and > MPI_SUM > >>>>>>> in accumulate/atomic operations in a standard-compliant way? > >>>>>>> > >>>>>>> accumulate_ops -- if set to same_op, the implementation will assume > >>>>>>> that all concurrent accumulate calls to the same target address > will > >>>>>>> use the same operation. If set to same_op_no_op, then the > >>>>>>> implementation will assume that all concurrent accumulate calls to > the > >>>>>>> same target address will use the same operation or MPI_NO_OP. This > can > >>>>>>> eliminate the need to protect access for certain operation types > where > >>>>>>> the hardware can guarantee atomicity. The default is same_op_no_op. > >>>>>>> > >>>>>>> We discuss this before and the resolution was not satisfying to me. > >>>>>>> > >>>>>>> Thanks, > >>>>>>> > >>>>>>> Jeff > >>>>>>> > >>>>>>> -- > >>>>>>> Jeff Hammond > >>>>>>> jeff.science(a)gmail.com > >>>>>>> _______________________________________________ > >>>>>>> mpiwg-rma mailing list > >>>>>>> mpiwg-rma(a)lists.mpi-forum.org > >>>>>>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma > >>>>>>> > >>>>>>> _______________________________________________ > >>>>>>> mpiwg-rma mailing list > >>>>>>> mpiwg-rma(a)lists.mpi-forum.org > >>>>>>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma > >>>>>> > >>>>>> _______________________________________________ > >>>>>> mpiwg-rma mailing list > >>>>>> mpiwg-rma(a)lists.mpi-forum.org > >>>>>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma > >>>>>> > >>>>>> _______________________________________________ > >>>>>> mpiwg-rma mailing list > >>>>>> mpiwg-rma(a)lists.mpi-forum.org > >>>>>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma > >>>>> > >>>>> _______________________________________________ > >>>>> mpiwg-rma mailing list > >>>>> mpiwg-rma(a)lists.mpi-forum.org > >>>>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma > >>>> > >>>> > >>>> > >>>> -- > >>>> Jeff Hammond > >>>> jeff.science(a)gmail.com > >>>> _______________________________________________ > >>>> mpiwg-rma mailing list > >>>> mpiwg-rma(a)lists.mpi-forum.org > >>>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma > >>> > >>> _______________________________________________ > >>> mpiwg-rma mailing list > >>> mpiwg-rma(a)lists.mpi-forum.org > >>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma > >> _______________________________________________ > >> mpiwg-rma mailing list > >> mpiwg-rma(a)lists.mpi-forum.org > >> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma > > > > _______________________________________________ > > mpiwg-rma mailing list > > mpiwg-rma(a)lists.mpi-forum.org > > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma > > > > -- > Jeff Hammond > jeff.science(a)gmail.com > _______________________________________________ > mpiwg-rma mailing list > mpiwg-rma(a)lists.mpi-forum.org > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma

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Re: [mpiwg-rma] same_op_no_op
by Jeff Hammond 13 Mar '14

13 Mar '14

It is extremely difficult to see that this is what the MPI-3 standard says. First we have this: "The outcome of concurrent accumulate operations to the same location with the same predefined datatype is as if the accumulates were done at that location in some serial order. Additional restrictions on the operation apply; see the info key accumulate_ops in Section 11.2.1. Concurrent accumulate operations with different origin and target pairs are not ordered. Thus, there is no guarantee that the entire call to an accumulate operation is executed atomically. The effect of this lack of atomicity is limited: The previous correctness conditions imply that a location updated by a call to an accumulate operation cannot be accessed by a load or an RMA call other than accumulate until the accumulate operation has completed (at the target). Different interleavings can lead to different results only to the extent that computer arithmetics are not truly associative or commutative. The outcome of accumulate operations with overlapping types of different sizes or target displacements is undefined." [11.7.1 Atomicity] Then we have this: "accumulate_ops — if set to same_op, the implementation will assume that all concurrent accumulate calls to the same target address will use the same operation. If set to same_op_no_op, then the implementation will assume that all concurrent accumulate calls to the same target address will use the same operation or MPI_NO_OP. This can eliminate the need to protect access for certain operation types where the hardware can guarantee atomicity. The default is same_op_no_op." [11.2.1 Window Creation] I was not aware that the definition of info keys was normative, given that implementations are free to ignore them. Even if info key text is normative, one has to infer from the fact that same_op_no_op is the default info behavior - and thus RMA semantic - that accumulate atomicity is restricted to the case where one uses the same op or noop but not replace. The MPI-2.2 spec is unambiguous because it explicitly requires the same operation in 11.7.1 Atomicity. This text was removed in MPI-3.0 in favor of the info key text. Best, Jeff On Tue, Mar 11, 2014 at 12:04 AM, Balaji, Pavan <balaji(a)anl.gov> wrote: > > MPI-2 defines atomicity only for the same operation, not any operation for MPI_ACCUMULATE. > > — Pavan > > On Mar 10, 2014, at 11:22 PM, Jeff Hammond <jeff.science(a)gmail.com> wrote: > >> So MPI-2 denied compatibility between replace and not-replace? >> >> Jeff >> >> Sent from my iPhone >> >>> On Mar 11, 2014, at 12:06 AM, "Balaji, Pavan" <balaji(a)anl.gov> wrote: >>> >>> >>> It doesn’t break backward compatibility. The info argument is still useful when you don’t want to use replace. I don’t see anything wrong with it. >>> >>>> On Mar 10, 2014, at 11:01 PM, Jeff Hammond <jeff.science(a)gmail.com> wrote: >>>> >>>> Does this or does this not break BW compatibility w.r.t. MPI-2.2 and >>>> did we do it intentionally? Unless we did so intentionally and >>>> explicitly, I will argue that the WG screwed up and the info key+val >>>> is invalid. >>>> >>>> Jeff >>>> >>>>> On Mon, Mar 10, 2014 at 11:03 PM, Balaji, Pavan <balaji(a)anl.gov> wrote: >>>>> >>>>> If a hardware can implement MPI_SUM, it should be able to implement MPI_SUM with 0 as well. >>>>> >>>>> But that’s not a generic solution. >>>>> >>>>> Jeff: at some point you were planning to bring in a ticket which does more combinations of operations than just same_op and no_op. Maybe it’s worthwhile bringing that up again? >>>>> >>>>> — Pavan >>>>> >>>>>> On Mar 10, 2014, at 9:26 PM, Jim Dinan <james.dinan(a)gmail.com> wrote: >>>>>> >>>>>> Maybe there's a loophole that I'm forgetting? >>>>>> >>>>>> >>>>>> On Mon, Mar 10, 2014 at 9:43 PM, Jeff Hammond <jeff.science(a)gmail.com> wrote: >>>>>> How the hell can I do GA or SHMEM then? Roll my own mutexes and commit perf-suicide? >>>>>> >>>>>> Jeff >>>>>> >>>>>> Sent from my iPhone >>>>>> >>>>>>> On Mar 10, 2014, at 8:32 PM, Jim Dinan <james.dinan(a)gmail.com> wrote: >>>>>>> >>>>>>> You can't use replace and sum concurrently at a given target address. >>>>>>> >>>>>>> ~Jim. >>>>>>> >>>>>>> On Mon, Mar 10, 2014 at 4:30 PM, Jeff Hammond <jeff.science(a)gmail.com> wrote: >>>>>>> Given the following, how do I use MPI_NO_OP, MPI_REPLACE and MPI_SUM >>>>>>> in accumulate/atomic operations in a standard-compliant way? >>>>>>> >>>>>>> accumulate_ops — if set to same_op, the implementation will assume >>>>>>> that all concurrent accumulate calls to the same target address will >>>>>>> use the same operation. If set to same_op_no_op, then the >>>>>>> implementation will assume that all concurrent accumulate calls to the >>>>>>> same target address will use the same operation or MPI_NO_OP. This can >>>>>>> eliminate the need to protect access for certain operation types where >>>>>>> the hardware can guarantee atomicity. The default is same_op_no_op. >>>>>>> >>>>>>> We discuss this before and the resolution was not satisfying to me. >>>>>>> >>>>>>> Thanks, >>>>>>> >>>>>>> Jeff >>>>>>> >>>>>>> -- >>>>>>> Jeff Hammond >>>>>>> jeff.science(a)gmail.com >>>>>>> _______________________________________________ >>>>>>> mpiwg-rma mailing list >>>>>>> mpiwg-rma(a)lists.mpi-forum.org >>>>>>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma >>>>>>> >>>>>>> _______________________________________________ >>>>>>> mpiwg-rma mailing list >>>>>>> mpiwg-rma(a)lists.mpi-forum.org >>>>>>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma >>>>>> >>>>>> _______________________________________________ >>>>>> mpiwg-rma mailing list >>>>>> mpiwg-rma(a)lists.mpi-forum.org >>>>>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma >>>>>> >>>>>> _______________________________________________ >>>>>> mpiwg-rma mailing list >>>>>> mpiwg-rma(a)lists.mpi-forum.org >>>>>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma >>>>> >>>>> _______________________________________________ >>>>> mpiwg-rma mailing list >>>>> mpiwg-rma(a)lists.mpi-forum.org >>>>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma >>>> >>>> >>>> >>>> -- >>>> Jeff Hammond >>>> jeff.science(a)gmail.com >>>> _______________________________________________ >>>> mpiwg-rma mailing list >>>> mpiwg-rma(a)lists.mpi-forum.org >>>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma >>> >>> _______________________________________________ >>> mpiwg-rma mailing list >>> mpiwg-rma(a)lists.mpi-forum.org >>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma >> _______________________________________________ >> mpiwg-rma mailing list >> mpiwg-rma(a)lists.mpi-forum.org >> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma > > _______________________________________________ > mpiwg-rma mailing list > mpiwg-rma(a)lists.mpi-forum.org > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma -- Jeff Hammond jeff.science(a)gmail.com

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Re: [mpiwg-rma] same_op_no_op
by Balaji, Pavan 11 Mar '14

11 Mar '14

MPI-2 defines atomicity only for the same operation, not any operation for MPI_ACCUMULATE. — Pavan On Mar 10, 2014, at 11:22 PM, Jeff Hammond <jeff.science(a)gmail.com> wrote: > So MPI-2 denied compatibility between replace and not-replace? > > Jeff > > Sent from my iPhone > >> On Mar 11, 2014, at 12:06 AM, "Balaji, Pavan" <balaji(a)anl.gov> wrote: >> >> >> It doesn’t break backward compatibility. The info argument is still useful when you don’t want to use replace. I don’t see anything wrong with it. >> >>> On Mar 10, 2014, at 11:01 PM, Jeff Hammond <jeff.science(a)gmail.com> wrote: >>> >>> Does this or does this not break BW compatibility w.r.t. MPI-2.2 and >>> did we do it intentionally? Unless we did so intentionally and >>> explicitly, I will argue that the WG screwed up and the info key+val >>> is invalid. >>> >>> Jeff >>> >>>> On Mon, Mar 10, 2014 at 11:03 PM, Balaji, Pavan <balaji(a)anl.gov> wrote: >>>> >>>> If a hardware can implement MPI_SUM, it should be able to implement MPI_SUM with 0 as well. >>>> >>>> But that’s not a generic solution. >>>> >>>> Jeff: at some point you were planning to bring in a ticket which does more combinations of operations than just same_op and no_op. Maybe it’s worthwhile bringing that up again? >>>> >>>> — Pavan >>>> >>>>> On Mar 10, 2014, at 9:26 PM, Jim Dinan <james.dinan(a)gmail.com> wrote: >>>>> >>>>> Maybe there's a loophole that I'm forgetting? >>>>> >>>>> >>>>> On Mon, Mar 10, 2014 at 9:43 PM, Jeff Hammond <jeff.science(a)gmail.com> wrote: >>>>> How the hell can I do GA or SHMEM then? Roll my own mutexes and commit perf-suicide? >>>>> >>>>> Jeff >>>>> >>>>> Sent from my iPhone >>>>> >>>>>> On Mar 10, 2014, at 8:32 PM, Jim Dinan <james.dinan(a)gmail.com> wrote: >>>>>> >>>>>> You can't use replace and sum concurrently at a given target address. >>>>>> >>>>>> ~Jim. >>>>>> >>>>>> On Mon, Mar 10, 2014 at 4:30 PM, Jeff Hammond <jeff.science(a)gmail.com> wrote: >>>>>> Given the following, how do I use MPI_NO_OP, MPI_REPLACE and MPI_SUM >>>>>> in accumulate/atomic operations in a standard-compliant way? >>>>>> >>>>>> accumulate_ops — if set to same_op, the implementation will assume >>>>>> that all concurrent accumulate calls to the same target address will >>>>>> use the same operation. If set to same_op_no_op, then the >>>>>> implementation will assume that all concurrent accumulate calls to the >>>>>> same target address will use the same operation or MPI_NO_OP. This can >>>>>> eliminate the need to protect access for certain operation types where >>>>>> the hardware can guarantee atomicity. The default is same_op_no_op. >>>>>> >>>>>> We discuss this before and the resolution was not satisfying to me. >>>>>> >>>>>> Thanks, >>>>>> >>>>>> Jeff >>>>>> >>>>>> -- >>>>>> Jeff Hammond >>>>>> jeff.science(a)gmail.com >>>>>> _______________________________________________ >>>>>> mpiwg-rma mailing list >>>>>> mpiwg-rma(a)lists.mpi-forum.org >>>>>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma >>>>>> >>>>>> _______________________________________________ >>>>>> mpiwg-rma mailing list >>>>>> mpiwg-rma(a)lists.mpi-forum.org >>>>>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma >>>>> >>>>> _______________________________________________ >>>>> mpiwg-rma mailing list >>>>> mpiwg-rma(a)lists.mpi-forum.org >>>>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma >>>>> >>>>> _______________________________________________ >>>>> mpiwg-rma mailing list >>>>> mpiwg-rma(a)lists.mpi-forum.org >>>>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma >>>> >>>> _______________________________________________ >>>> mpiwg-rma mailing list >>>> mpiwg-rma(a)lists.mpi-forum.org >>>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma >>> >>> >>> >>> -- >>> Jeff Hammond >>> jeff.science(a)gmail.com >>> _______________________________________________ >>> mpiwg-rma mailing list >>> mpiwg-rma(a)lists.mpi-forum.org >>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma >> >> _______________________________________________ >> mpiwg-rma mailing list >> mpiwg-rma(a)lists.mpi-forum.org >> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma > _______________________________________________ > mpiwg-rma mailing list > mpiwg-rma(a)lists.mpi-forum.org > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma

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Re: [mpiwg-rma] same_op_no_op
by Jeff Hammond 10 Mar '14

10 Mar '14

So MPI-2 denied compatibility between replace and not-replace? Jeff Sent from my iPhone > On Mar 11, 2014, at 12:06 AM, "Balaji, Pavan" <balaji(a)anl.gov> wrote: > > > It doesn’t break backward compatibility. The info argument is still useful when you don’t want to use replace. I don’t see anything wrong with it. > >> On Mar 10, 2014, at 11:01 PM, Jeff Hammond <jeff.science(a)gmail.com> wrote: >> >> Does this or does this not break BW compatibility w.r.t. MPI-2.2 and >> did we do it intentionally? Unless we did so intentionally and >> explicitly, I will argue that the WG screwed up and the info key+val >> is invalid. >> >> Jeff >> >>> On Mon, Mar 10, 2014 at 11:03 PM, Balaji, Pavan <balaji(a)anl.gov> wrote: >>> >>> If a hardware can implement MPI_SUM, it should be able to implement MPI_SUM with 0 as well. >>> >>> But that’s not a generic solution. >>> >>> Jeff: at some point you were planning to bring in a ticket which does more combinations of operations than just same_op and no_op. Maybe it’s worthwhile bringing that up again? >>> >>> — Pavan >>> >>>> On Mar 10, 2014, at 9:26 PM, Jim Dinan <james.dinan(a)gmail.com> wrote: >>>> >>>> Maybe there's a loophole that I'm forgetting? >>>> >>>> >>>> On Mon, Mar 10, 2014 at 9:43 PM, Jeff Hammond <jeff.science(a)gmail.com> wrote: >>>> How the hell can I do GA or SHMEM then? Roll my own mutexes and commit perf-suicide? >>>> >>>> Jeff >>>> >>>> Sent from my iPhone >>>> >>>>> On Mar 10, 2014, at 8:32 PM, Jim Dinan <james.dinan(a)gmail.com> wrote: >>>>> >>>>> You can't use replace and sum concurrently at a given target address. >>>>> >>>>> ~Jim. >>>>> >>>>> On Mon, Mar 10, 2014 at 4:30 PM, Jeff Hammond <jeff.science(a)gmail.com> wrote: >>>>> Given the following, how do I use MPI_NO_OP, MPI_REPLACE and MPI_SUM >>>>> in accumulate/atomic operations in a standard-compliant way? >>>>> >>>>> accumulate_ops — if set to same_op, the implementation will assume >>>>> that all concurrent accumulate calls to the same target address will >>>>> use the same operation. If set to same_op_no_op, then the >>>>> implementation will assume that all concurrent accumulate calls to the >>>>> same target address will use the same operation or MPI_NO_OP. This can >>>>> eliminate the need to protect access for certain operation types where >>>>> the hardware can guarantee atomicity. The default is same_op_no_op. >>>>> >>>>> We discuss this before and the resolution was not satisfying to me. >>>>> >>>>> Thanks, >>>>> >>>>> Jeff >>>>> >>>>> -- >>>>> Jeff Hammond >>>>> jeff.science(a)gmail.com >>>>> _______________________________________________ >>>>> mpiwg-rma mailing list >>>>> mpiwg-rma(a)lists.mpi-forum.org >>>>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma >>>>> >>>>> _______________________________________________ >>>>> mpiwg-rma mailing list >>>>> mpiwg-rma(a)lists.mpi-forum.org >>>>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma >>>> >>>> _______________________________________________ >>>> mpiwg-rma mailing list >>>> mpiwg-rma(a)lists.mpi-forum.org >>>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma >>>> >>>> _______________________________________________ >>>> mpiwg-rma mailing list >>>> mpiwg-rma(a)lists.mpi-forum.org >>>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma >>> >>> _______________________________________________ >>> mpiwg-rma mailing list >>> mpiwg-rma(a)lists.mpi-forum.org >>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma >> >> >> >> -- >> Jeff Hammond >> jeff.science(a)gmail.com >> _______________________________________________ >> mpiwg-rma mailing list >> mpiwg-rma(a)lists.mpi-forum.org >> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma > > _______________________________________________ > mpiwg-rma mailing list > mpiwg-rma(a)lists.mpi-forum.org > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma

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Re: [mpiwg-rma] same_op_no_op
by Balaji, Pavan 10 Mar '14

10 Mar '14

It doesn’t break backward compatibility. The info argument is still useful when you don’t want to use replace. I don’t see anything wrong with it. On Mar 10, 2014, at 11:01 PM, Jeff Hammond <jeff.science(a)gmail.com> wrote: > Does this or does this not break BW compatibility w.r.t. MPI-2.2 and > did we do it intentionally? Unless we did so intentionally and > explicitly, I will argue that the WG screwed up and the info key+val > is invalid. > > Jeff > > On Mon, Mar 10, 2014 at 11:03 PM, Balaji, Pavan <balaji(a)anl.gov> wrote: >> >> If a hardware can implement MPI_SUM, it should be able to implement MPI_SUM with 0 as well. >> >> But that’s not a generic solution. >> >> Jeff: at some point you were planning to bring in a ticket which does more combinations of operations than just same_op and no_op. Maybe it’s worthwhile bringing that up again? >> >> — Pavan >> >> On Mar 10, 2014, at 9:26 PM, Jim Dinan <james.dinan(a)gmail.com> wrote: >> >>> Maybe there's a loophole that I'm forgetting? >>> >>> >>> On Mon, Mar 10, 2014 at 9:43 PM, Jeff Hammond <jeff.science(a)gmail.com> wrote: >>> How the hell can I do GA or SHMEM then? Roll my own mutexes and commit perf-suicide? >>> >>> Jeff >>> >>> Sent from my iPhone >>> >>> On Mar 10, 2014, at 8:32 PM, Jim Dinan <james.dinan(a)gmail.com> wrote: >>> >>>> You can't use replace and sum concurrently at a given target address. >>>> >>>> ~Jim. >>>> >>>> On Mon, Mar 10, 2014 at 4:30 PM, Jeff Hammond <jeff.science(a)gmail.com> wrote: >>>> Given the following, how do I use MPI_NO_OP, MPI_REPLACE and MPI_SUM >>>> in accumulate/atomic operations in a standard-compliant way? >>>> >>>> accumulate_ops — if set to same_op, the implementation will assume >>>> that all concurrent accumulate calls to the same target address will >>>> use the same operation. If set to same_op_no_op, then the >>>> implementation will assume that all concurrent accumulate calls to the >>>> same target address will use the same operation or MPI_NO_OP. This can >>>> eliminate the need to protect access for certain operation types where >>>> the hardware can guarantee atomicity. The default is same_op_no_op. >>>> >>>> We discuss this before and the resolution was not satisfying to me. >>>> >>>> Thanks, >>>> >>>> Jeff >>>> >>>> -- >>>> Jeff Hammond >>>> jeff.science(a)gmail.com >>>> _______________________________________________ >>>> mpiwg-rma mailing list >>>> mpiwg-rma(a)lists.mpi-forum.org >>>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma >>>> >>>> _______________________________________________ >>>> mpiwg-rma mailing list >>>> mpiwg-rma(a)lists.mpi-forum.org >>>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma >>> >>> _______________________________________________ >>> mpiwg-rma mailing list >>> mpiwg-rma(a)lists.mpi-forum.org >>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma >>> >>> _______________________________________________ >>> mpiwg-rma mailing list >>> mpiwg-rma(a)lists.mpi-forum.org >>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma >> >> _______________________________________________ >> mpiwg-rma mailing list >> mpiwg-rma(a)lists.mpi-forum.org >> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma > > > > -- > Jeff Hammond > jeff.science(a)gmail.com > _______________________________________________ > mpiwg-rma mailing list > mpiwg-rma(a)lists.mpi-forum.org > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma

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Re: [mpiwg-rma] same_op_no_op
by Jeff Hammond 10 Mar '14

10 Mar '14

Does this or does this not break BW compatibility w.r.t. MPI-2.2 and did we do it intentionally? Unless we did so intentionally and explicitly, I will argue that the WG screwed up and the info key+val is invalid. Jeff On Mon, Mar 10, 2014 at 11:03 PM, Balaji, Pavan <balaji(a)anl.gov> wrote: > > If a hardware can implement MPI_SUM, it should be able to implement MPI_SUM with 0 as well. > > But that’s not a generic solution. > > Jeff: at some point you were planning to bring in a ticket which does more combinations of operations than just same_op and no_op. Maybe it’s worthwhile bringing that up again? > > — Pavan > > On Mar 10, 2014, at 9:26 PM, Jim Dinan <james.dinan(a)gmail.com> wrote: > >> Maybe there's a loophole that I'm forgetting? >> >> >> On Mon, Mar 10, 2014 at 9:43 PM, Jeff Hammond <jeff.science(a)gmail.com> wrote: >> How the hell can I do GA or SHMEM then? Roll my own mutexes and commit perf-suicide? >> >> Jeff >> >> Sent from my iPhone >> >> On Mar 10, 2014, at 8:32 PM, Jim Dinan <james.dinan(a)gmail.com> wrote: >> >>> You can't use replace and sum concurrently at a given target address. >>> >>> ~Jim. >>> >>> On Mon, Mar 10, 2014 at 4:30 PM, Jeff Hammond <jeff.science(a)gmail.com> wrote: >>> Given the following, how do I use MPI_NO_OP, MPI_REPLACE and MPI_SUM >>> in accumulate/atomic operations in a standard-compliant way? >>> >>> accumulate_ops — if set to same_op, the implementation will assume >>> that all concurrent accumulate calls to the same target address will >>> use the same operation. If set to same_op_no_op, then the >>> implementation will assume that all concurrent accumulate calls to the >>> same target address will use the same operation or MPI_NO_OP. This can >>> eliminate the need to protect access for certain operation types where >>> the hardware can guarantee atomicity. The default is same_op_no_op. >>> >>> We discuss this before and the resolution was not satisfying to me. >>> >>> Thanks, >>> >>> Jeff >>> >>> -- >>> Jeff Hammond >>> jeff.science(a)gmail.com >>> _______________________________________________ >>> mpiwg-rma mailing list >>> mpiwg-rma(a)lists.mpi-forum.org >>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma >>> >>> _______________________________________________ >>> mpiwg-rma mailing list >>> mpiwg-rma(a)lists.mpi-forum.org >>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma >> >> _______________________________________________ >> mpiwg-rma mailing list >> mpiwg-rma(a)lists.mpi-forum.org >> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma >> >> _______________________________________________ >> mpiwg-rma mailing list >> mpiwg-rma(a)lists.mpi-forum.org >> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma > > _______________________________________________ > mpiwg-rma mailing list > mpiwg-rma(a)lists.mpi-forum.org > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma -- Jeff Hammond jeff.science(a)gmail.com

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Re: [mpiwg-rma] same_op_no_op
by Balaji, Pavan 10 Mar '14

10 Mar '14

If a hardware can implement MPI_SUM, it should be able to implement MPI_SUM with 0 as well. But that’s not a generic solution. Jeff: at some point you were planning to bring in a ticket which does more combinations of operations than just same_op and no_op. Maybe it’s worthwhile bringing that up again? — Pavan On Mar 10, 2014, at 9:26 PM, Jim Dinan <james.dinan(a)gmail.com> wrote: > Maybe there's a loophole that I'm forgetting? > > > On Mon, Mar 10, 2014 at 9:43 PM, Jeff Hammond <jeff.science(a)gmail.com> wrote: > How the hell can I do GA or SHMEM then? Roll my own mutexes and commit perf-suicide? > > Jeff > > Sent from my iPhone > > On Mar 10, 2014, at 8:32 PM, Jim Dinan <james.dinan(a)gmail.com> wrote: > >> You can't use replace and sum concurrently at a given target address. >> >> ~Jim. >> >> On Mon, Mar 10, 2014 at 4:30 PM, Jeff Hammond <jeff.science(a)gmail.com> wrote: >> Given the following, how do I use MPI_NO_OP, MPI_REPLACE and MPI_SUM >> in accumulate/atomic operations in a standard-compliant way? >> >> accumulate_ops — if set to same_op, the implementation will assume >> that all concurrent accumulate calls to the same target address will >> use the same operation. If set to same_op_no_op, then the >> implementation will assume that all concurrent accumulate calls to the >> same target address will use the same operation or MPI_NO_OP. This can >> eliminate the need to protect access for certain operation types where >> the hardware can guarantee atomicity. The default is same_op_no_op. >> >> We discuss this before and the resolution was not satisfying to me. >> >> Thanks, >> >> Jeff >> >> -- >> Jeff Hammond >> jeff.science(a)gmail.com >> _______________________________________________ >> mpiwg-rma mailing list >> mpiwg-rma(a)lists.mpi-forum.org >> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma >> >> _______________________________________________ >> mpiwg-rma mailing list >> mpiwg-rma(a)lists.mpi-forum.org >> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma > > _______________________________________________ > mpiwg-rma mailing list > mpiwg-rma(a)lists.mpi-forum.org > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma > > _______________________________________________ > mpiwg-rma mailing list > mpiwg-rma(a)lists.mpi-forum.org > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma

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Re: [mpiwg-rma] same_op_no_op
by Jim Dinan 10 Mar '14

10 Mar '14

Maybe there's a loophole that I'm forgetting? On Mon, Mar 10, 2014 at 9:43 PM, Jeff Hammond <jeff.science(a)gmail.com>wrote: > How the hell can I do GA or SHMEM then? Roll my own mutexes and commit > perf-suicide? > > Jeff > > Sent from my iPhone > > On Mar 10, 2014, at 8:32 PM, Jim Dinan <james.dinan(a)gmail.com> wrote: > > You can't use replace and sum concurrently at a given target address. > > ~Jim. > > On Mon, Mar 10, 2014 at 4:30 PM, Jeff Hammond <jeff.science(a)gmail.com>wrote: > >> Given the following, how do I use MPI_NO_OP, MPI_REPLACE and MPI_SUM >> in accumulate/atomic operations in a standard-compliant way? >> >> accumulate_ops -- if set to same_op, the implementation will assume >> that all concurrent accumulate calls to the same target address will >> use the same operation. If set to same_op_no_op, then the >> implementation will assume that all concurrent accumulate calls to the >> same target address will use the same operation or MPI_NO_OP. This can >> eliminate the need to protect access for certain operation types where >> the hardware can guarantee atomicity. The default is same_op_no_op. >> >> We discuss this before and the resolution was not satisfying to me. >> >> Thanks, >> >> Jeff >> >> -- >> Jeff Hammond >> jeff.science(a)gmail.com >> _______________________________________________ >> mpiwg-rma mailing list >> mpiwg-rma(a)lists.mpi-forum.org >> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma > > > _______________________________________________ > mpiwg-rma mailing list > mpiwg-rma(a)lists.mpi-forum.org > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma > > > _______________________________________________ > mpiwg-rma mailing list > mpiwg-rma(a)lists.mpi-forum.org > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma >

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Re: [mpiwg-rma] same_op_no_op
by Jeff Hammond 10 Mar '14

10 Mar '14

How the hell can I do GA or SHMEM then? Roll my own mutexes and commit perf-suicide? Jeff Sent from my iPhone > On Mar 10, 2014, at 8:32 PM, Jim Dinan <james.dinan(a)gmail.com> wrote: > > You can't use replace and sum concurrently at a given target address. > > ~Jim. > >> On Mon, Mar 10, 2014 at 4:30 PM, Jeff Hammond <jeff.science(a)gmail.com> wrote: >> Given the following, how do I use MPI_NO_OP, MPI_REPLACE and MPI_SUM >> in accumulate/atomic operations in a standard-compliant way? >> >> accumulate_ops — if set to same_op, the implementation will assume >> that all concurrent accumulate calls to the same target address will >> use the same operation. If set to same_op_no_op, then the >> implementation will assume that all concurrent accumulate calls to the >> same target address will use the same operation or MPI_NO_OP. This can >> eliminate the need to protect access for certain operation types where >> the hardware can guarantee atomicity. The default is same_op_no_op. >> >> We discuss this before and the resolution was not satisfying to me. >> >> Thanks, >> >> Jeff >> >> -- >> Jeff Hammond >> jeff.science(a)gmail.com >> _______________________________________________ >> mpiwg-rma mailing list >> mpiwg-rma(a)lists.mpi-forum.org >> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma > > _______________________________________________ > mpiwg-rma mailing list > mpiwg-rma(a)lists.mpi-forum.org > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma

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Re: [mpiwg-rma] same_op_no_op
by Jim Dinan 10 Mar '14

10 Mar '14

You can't use replace and sum concurrently at a given target address. ~Jim. On Mon, Mar 10, 2014 at 4:30 PM, Jeff Hammond <jeff.science(a)gmail.com>wrote: > Given the following, how do I use MPI_NO_OP, MPI_REPLACE and MPI_SUM > in accumulate/atomic operations in a standard-compliant way? > > accumulate_ops -- if set to same_op, the implementation will assume > that all concurrent accumulate calls to the same target address will > use the same operation. If set to same_op_no_op, then the > implementation will assume that all concurrent accumulate calls to the > same target address will use the same operation or MPI_NO_OP. This can > eliminate the need to protect access for certain operation types where > the hardware can guarantee atomicity. The default is same_op_no_op. > > We discuss this before and the resolution was not satisfying to me. > > Thanks, > > Jeff > > -- > Jeff Hammond > jeff.science(a)gmail.com > _______________________________________________ > mpiwg-rma mailing list > mpiwg-rma(a)lists.mpi-forum.org > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma

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