- mpiwg-fortran - mailman3.cels.anl.gov

Re: [MPIWG Fortran] Another MPI_SIZEOF question
by Bill Long 10 Jun '14

10 Jun '14

On Jun 10, 2014, at 3:55 PM, William Gropp <wgropp(a)illinois.edu> wrote: > On SIZEOF, the language in the standard for the argument is > > a Fortran variable of numeric intrinsic type (choice) > > I read this as different from "a *scalar* Fortran variable of numeric intrinsic type (choice)", but I may be interpreting the language too broadly. My reading is probably intended, however, because the Advice to users says: My assumption is that arrays are acceptable arguments. The problem with treating the argument to MPI_SIZEOF the same was as a choice buffer (using directives like IGNORE_TKR) is that the routine does need to know the TYPE of the argument. > > > If you want an errata, I'd consider this: > I’d be generally in favor of avoiding mention of “Fortran 77”. The operational issues are only whether mpif.h is still supported, and if it is, whether it is compatible with fixed source form. As a practical matter, I don’t know of any vendor that supplies a “Fortran 77” compiler that does not also supply a more modern Fortran compiler - at least F95. In practice, the “F77” compiler, if it exists at all, is the same compiler as the modern one, except with different default options (for source form, for example). > > Page 616, line 32. The following is suspicious: "MPI provides named datatypes corresponding to standard Fortran 77 numeric types:". Is there a way to describe this that does not refer to Fortran 77? Just delete the “77”. The list of intrinsic numeric types is the same in F08 as it was in F77. Cheers, Bill > > There are a few other places where Fortran 77 is mentioned, but I think they're ok, if dated. But as long as mpif.h must contain, for example, any interface blocks, then MPI-3 cannot be used with Fortran 77 and it is incorrect and misleading to suggest otherwise. > > An alternative is to remove all of the functions that were not present in the "basic" Fortran support from the mpif.h module, at least as a requirement. This route, however, will require a very careful search through the document for other places where there may be requirements that make it impossible to implement against standard-practice Fortran 77 compilers (and given the MPI-3 standard's endorsement of the use of non-standard extensions to permit the newer interfaces to be compiled, lets not argue about whether only fully and strictly Fortran 77 should be considered). Given both the age and the complexity of the task, I believe a more robust solution is to explicitly drop support for Fortran 77. It may *also* be necessary to weaken the requirement for MPI_SIZEOF in order to permit any but the most recent Fortran compilers to be used. > > Bill > > William Gropp > Director, Parallel Computing Institute > Thomas M. Siebel Chair in Computer Science > University of Illinois Urbana-Champaign > > > > > > On Jun 10, 2014, at 4:41 PM, Jeff Squyres (jsquyres) wrote: > >> On Jun 10, 2014, at 10:10 AM, William Gropp <wgropp(a)illinois.edu> wrote: >> >>> Jeff, as I noted before, in MPI-2, MPI_SIZEOF was not required for the Fortran "basic" support, thus MPI-2 did not break the existing practice with Fortran 77 compilers and the mpif.h include file (see the beginning of section 10.2.5 in MPI-2). >> >> Sorry, you're right -- you even said this earlier in the thread. My mistake. >> >>> The issue is deciding that mpif.h is not a way to compile MPI programs with a Fortran compiler that is for Fortran before 2008 + TS29113 but simply a different interface to the one true and only Fortran interface - which isn't even yet standard (since it requires TS29113). >> >> Same question as I asked before: Is 2003 or 2008+TS29113 required for SIZEOF? I have no knowledge of when INTERFACE blocks were added to Fortran. >> >> I'm asking this because DIMENSION(..) is *useful* to implement MPI_SIZEOF succinctly/easily, but it is not *required*. >> >> -- >> Jeff Squyres >> jsquyres(a)cisco.com >> For corporate legal information go to: http://www.cisco.com/web/about/doing_business/legal/cri/ >> >> _______________________________________________ >> mpiwg-fortran mailing list >> mpiwg-fortran(a)lists.mpi-forum.org >> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-fortran > > _______________________________________________ > mpiwg-fortran mailing list > mpiwg-fortran(a)lists.mpi-forum.org > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-fortran Bill Long longb(a)cray.com Fortran Technical Suport & voice: 651-605-9024 Bioinformatics Software Development fax: 651-605-9142 Cray Inc./ Cray Plaza, Suite 210/ 380 Jackson St./ St. Paul, MN 55101

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Re: [MPIWG Fortran] Another MPI_SIZEOF question
by William Gropp 10 Jun '14

10 Jun '14

On SIZEOF, the language in the standard for the argument is a Fortran variable of numeric intrinsic type (choice) I read this as different from "a *scalar* Fortran variable of numeric intrinsic type (choice)", but I may be interpreting the language too broadly. My reading is probably intended, however, because the Advice to users says: If given an array argument, it returns the size of the base element, not the size of the whole array. Thus, the argument must be acceptable as an array (and note that the same language is present in MPI-2.0, and the Fortran 2008+TS29113 binding includes DIMENSION(..) Thus, I believe that MPI_SIZEOF has the same choice parameter requirements of the communication routines such as MPI_SEND. If not, then this part of the advice to users is bogus, and the parameter should clearly be labeled as scalar only. And while not technically impossible to implement without DIMENSION(..), it is, as I said before, agreed to be impractical. And it cannot be done in Fortran 77 (and is hard to do in anything less than F08+TS29113). So that fact remains that in MPI-2, the "basic" support was setup to permit the use of Fortran 77 compilers, under the near universal extension that (and I will use the shorthand here) different types of variables could be passed to the same argument position in a routine. With MPI-3.0, this is no longer possible; at least F90 is required, and a *practical* full implementation requires much more than F90. If you want an errata, I'd consider this: Strike the sentence "MPI can still be used with most Fortran 77 compilers, as noted below." on page 81 line 47. It is untrue; it will be hard to be perfectly compliant without the full F08+TS29113. Page 85, line 26ff, strike the sentence that starts "On Fortran 77 systems" Page 103, lines 7-14. Strike this entire advice to users - its from MPI-2.0, when there was MPI_Address and MPI_Get_address. Page 451, lines 29-30. Delete "Fortran 77 users can use (non- portably) bit vector IOR on systems that support it." Page 492, lines 45-46. Delete "Fortran 77 users can use (nonportably) bit vector IOR on systems that support it." Page 497, Example 13.1. Either delete the entire example or change it to Fortran 9x or above. Page 545, lines 16-17. Delete "In Fortran 77 environments that do not support KIND parameters, MPI_Offset arguments should be declared as an INTEGER of suitable size." Page 605, lines 8-9. Delete "To support Fortran 77 as well as Fortran 90 and later, it may be necessary to eliminate all comments from mpif.h. " Page 616, line 32. The following is suspicious: "MPI provides named datatypes corresponding to standard Fortran 77 numeric types:". Is there a way to describe this that does not refer to Fortran 77? There are a few other places where Fortran 77 is mentioned, but I think they're ok, if dated. But as long as mpif.h must contain, for example, any interface blocks, then MPI-3 cannot be used with Fortran 77 and it is incorrect and misleading to suggest otherwise. An alternative is to remove all of the functions that were not present in the "basic" Fortran support from the mpif.h module, at least as a requirement. This route, however, will require a very careful search through the document for other places where there may be requirements that make it impossible to implement against standard-practice Fortran 77 compilers (and given the MPI-3 standard's endorsement of the use of non-standard extensions to permit the newer interfaces to be compiled, lets not argue about whether only fully and strictly Fortran 77 should be considered). Given both the age and the complexity of the task, I believe a more robust solution is to explicitly drop support for Fortran 77. It may *also* be necessary to weaken the requirement for MPI_SIZEOF in order to permit any but the most recent Fortran compilers to be used. Bill William Gropp Director, Parallel Computing Institute Thomas M. Siebel Chair in Computer Science University of Illinois Urbana-Champaign On Jun 10, 2014, at 4:41 PM, Jeff Squyres (jsquyres) wrote: > On Jun 10, 2014, at 10:10 AM, William Gropp <wgropp(a)illinois.edu> wrote: > >> Jeff, as I noted before, in MPI-2, MPI_SIZEOF was not required for the Fortran "basic" support, thus MPI-2 did not break the existing practice with Fortran 77 compilers and the mpif.h include file (see the beginning of section 10.2.5 in MPI-2). > > Sorry, you're right -- you even said this earlier in the thread. My mistake. > >> The issue is deciding that mpif.h is not a way to compile MPI programs with a Fortran compiler that is for Fortran before 2008 + TS29113 but simply a different interface to the one true and only Fortran interface - which isn't even yet standard (since it requires TS29113). > > Same question as I asked before: Is 2003 or 2008+TS29113 required for SIZEOF? I have no knowledge of when INTERFACE blocks were added to Fortran. > > I'm asking this because DIMENSION(..) is *useful* to implement MPI_SIZEOF succinctly/easily, but it is not *required*. > > -- > Jeff Squyres > jsquyres(a)cisco.com > For corporate legal information go to: http://www.cisco.com/web/about/doing_business/legal/cri/ > > _______________________________________________ > mpiwg-fortran mailing list > mpiwg-fortran(a)lists.mpi-forum.org > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-fortran

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Re: [MPIWG Fortran] Another MPI_SIZEOF question
by Bill Long 10 Jun '14

10 Jun '14

On Jun 10, 2014, at 9:41 AM, Jeff Squyres (jsquyres) <jsquyres(a)cisco.com> wrote: > > Same question as I asked before: Is 2003 or 2008+TS29113 required for SIZEOF? I have no knowledge of when INTERFACE blocks were added to Fortran. Interface blocks were added in F90. > > I'm asking this because DIMENSION(..) is *useful* to implement MPI_SIZEOF succinctly/easily, but it is not *required*. MPI_SIZEOF is most easily written with the new features, but it is possible (tedious) to write a version without. Cheers, Bill Bill Long longb(a)cray.com Fortran Technical Suport & voice: 651-605-9024 Bioinformatics Software Development fax: 651-605-9142 Cray Inc./ Cray Plaza, Suite 210/ 380 Jackson St./ St. Paul, MN 55101

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Re: [MPIWG Fortran] Another MPI_SIZEOF question
by Jeff Squyres (jsquyres) 10 Jun '14

10 Jun '14

On Jun 10, 2014, at 10:10 AM, William Gropp <wgropp(a)illinois.edu> wrote: > Jeff, as I noted before, in MPI-2, MPI_SIZEOF was not required for the Fortran "basic" support, thus MPI-2 did not break the existing practice with Fortran 77 compilers and the mpif.h include file (see the beginning of section 10.2.5 in MPI-2). Sorry, you're right -- you even said this earlier in the thread. My mistake. > The issue is deciding that mpif.h is not a way to compile MPI programs with a Fortran compiler that is for Fortran before 2008 + TS29113 but simply a different interface to the one true and only Fortran interface - which isn't even yet standard (since it requires TS29113). Same question as I asked before: Is 2003 or 2008+TS29113 required for SIZEOF? I have no knowledge of when INTERFACE blocks were added to Fortran. I'm asking this because DIMENSION(..) is *useful* to implement MPI_SIZEOF succinctly/easily, but it is not *required*. -- Jeff Squyres jsquyres(a)cisco.com For corporate legal information go to: http://www.cisco.com/web/about/doing_business/legal/cri/

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Re: [MPIWG Fortran] Another MPI_SIZEOF question
by William Gropp 10 Jun '14

10 Jun '14

Rolf, The problem is that the standard also requires MPI_SIZEOF to be supported by every version of the Fortran interfaces, even mpif.h. This was *not* the case in MPI-2. The standard even acknowledges that MPI_SIZEOF requires overloading, and that overloading definition is required in mpif.h . Thus, mpif.h cannot be implemented in a way that supports a Fortran 77 compiler. Jeff, as I noted before, in MPI-2, MPI_SIZEOF was not required for the Fortran "basic" support, thus MPI-2 did not break the existing practice with Fortran 77 compilers and the mpif.h include file (see the beginning of section 10.2.5 in MPI-2). And yes, as has been noted for a long time, the MPI-2 definition of Fortran interfaces for the "Extended" Fortran support were impractical within standard Fortran. So MPI has been working around limitations in the Fortran since the very beginning. I think all of us are happy to see Fortran evolving to the point where it is possible to implement a library that can move data (this could be a single-core I/O library; it need not be MPI). That's not the issue. The issue is deciding that mpif.h is not a way to compile MPI programs with a Fortran compiler that is for Fortran before 2008 + TS29113 but simply a different interface to the one true and only Fortran interface - which isn't even yet standard (since it requires TS29113). Bill William Gropp Director, Parallel Computing Institute Thomas M. Siebel Chair in Computer Science University of Illinois Urbana-Champaign On Jun 10, 2014, at 3:48 PM, Rolf Rabenseifner wrote: >> As far as I can tell from the >> requirement that MPI_SIZEOF be supported, mpif.h also requires >> Fortran 2008 + TS29113, meaning that many legacy MPI programs cannot >> be compiled with a standard conforming MPI implementation and a >> Fortran compiler that implements only, say, Fortran 2008 (but not >> the TS29113, which is *not* part of the standard) or Fortran 2003. > > Section 17.1.6 on page 609 "MPI for Different Fortran Standard Versions" > tries to define the rules for standard compliant MPI-3.0 with > a Fortran 77, 90, 95, 2003, and 2003/2008+TS29113 compiler, > i.e., MPI-3.0 can be implemented with the restrictions, > e.g., MPI_SUBARRAYS_SUPPORTED needs to be set to .FALSE.. > > Rolf > > > > ----- Original Message ----- >> From: "William Gropp" <wgropp(a)illinois.edu> >> To: "MPI-WG Fortran working group" <mpiwg-fortran(a)lists.mpi-forum.org> >> Sent: Tuesday, June 10, 2014 3:06:08 PM >> Subject: Re: [MPIWG Fortran] Another MPI_SIZEOF question >> >> >> This naming corresponds to MPI-3 but not to the use in MPI-1 nor to >> what some users may still want, which is what Jeff is talking about. >> >> >> >> And note: When the original MPI Fortran interface was defined, it was >> known not to be standard conformant - in fact, I raised that issue >> and raised a straw man alternative that was not accepted by the MPI >> Forum. The fact at the time was that it was widely recognized that >> Fortran's (meaning Fortran 77) strict rules with the absence of any >> escape combined with no real general data mechanism, needed by many >> different libraries, not just MPI, made the type checking rules >> impractical, and virtually no compiler of the time implemented this >> check (the only one I knew of was WATFOR, and you could turn it >> off). >> >> >> Despite this, many applications were written using Fortran. Those >> applications in practice, despite not conforming to the letter of >> the standard, were portable and contributed to the success of MPI. >> I don't find comments about "MPI never supported Fortran" to be >> useful, even if they are technically true. >> >> >> In my opinion, the use of "mpif.h" should have been to support >> existing programs in their existing compilation environments. That >> might be fixed-format early Fortran, either Fortran 77 or perhaps >> Fortran 90 or Fortran 95. The goal of MPI-3 should have been to >> ensure that new programs used the mpi or mpi_f08 modules and that >> existing programs could continue to be used. That is *not* the >> situation that we have now. As far as I can tell from the >> requirement that MPI_SIZEOF be supported, mpif.h also requires >> Fortran 2008 + TS29113, meaning that many legacy MPI programs cannot >> be compiled with a standard conforming MPI implementation and a >> Fortran compiler that implements only, say, Fortran 2008 (but not >> the TS29113, which is *not* part of the standard) or Fortran 2003. >> >> >> Bill >> >> >> >> >> >> >> William Gropp >> Director, Parallel Computing Institute Thomas M. Siebel Chair in >> Computer Science >> >> >> University of Illinois Urbana-Champaign >> >> >> >> >> >> >> >> On Jun 10, 2014, at 2:44 PM, Jeff Squyres (jsquyres) wrote: >> >> >> >> On Jun 10, 2014, at 8:35 AM, Jeff Hammond < jeff.science(a)gmail.com > >> wrote: >> >> >> >> What shorthand will you permit for what is meant when Bill and I >> refer >> >> >> to Fortran 77 support in MPI that distinguishes it from F90 and F08 >> >> >> module support? >> >> I usually say "the mpif.h interface", "the (Fortran) mpi module", and >> "the mpi_f08 module". Indeed, I have renamed the "ompi/mpi/f77" and >> "ompi/mpi/f90" directories from previous versions of OMPI to >> "ompi/mpi/fortran/mpifh" and "ompi/mpi/fortran/use-mpi". >> >> Meaning: I have seen the error of my ways and corrected myself. You >> can, too. :-) >> >> -- >> Jeff Squyres >> jsquyres(a)cisco.com >> For corporate legal information go to: >> http://www.cisco.com/web/about/doing_business/legal/cri/ >> >> _______________________________________________ >> mpiwg-fortran mailing list >> mpiwg-fortran(a)lists.mpi-forum.org >> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-fortran >> >> >> _______________________________________________ >> mpiwg-fortran mailing list >> mpiwg-fortran(a)lists.mpi-forum.org >> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-fortran > > -- > Dr. Rolf Rabenseifner . . . . . . . . . .. email rabenseifner(a)hlrs.de > High Performance Computing Center (HLRS) . phone ++49(0)711/685-65530 > University of Stuttgart . . . . . . . . .. fax ++49(0)711 / 685-65832 > Head of Dpmt Parallel Computing . . . www.hlrs.de/people/rabenseifner > Nobelstr. 19, D-70550 Stuttgart, Germany . . . . (Office: Room 1.307) > _______________________________________________ > mpiwg-fortran mailing list > mpiwg-fortran(a)lists.mpi-forum.org > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-fortran

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Re: [MPIWG Fortran] Another MPI_SIZEOF question
by Jeff Squyres (jsquyres) 10 Jun '14

10 Jun '14

On Jun 10, 2014, at 9:06 AM, William Gropp <wgropp(a)illinois.edu> wrote: > This naming corresponds to MPI-3 but not to the use in MPI-1 nor to what some users may still want, which is what Jeff is talking about. There are really two issues at play here: 1. Which MPI interface an application is using: C, Fortran mpif.h, Fortran mpi module, or Fortran mpi_f08 module 2. Which Fortran compiler an application needs Trying to munge these two issues into a single label has led to all kinds of confusion and silly religious debates ...like this one. > In my opinion, the use of "mpif.h" should have been to support existing programs in their existing compilation environments. That might be fixed-format early Fortran, either Fortran 77 or perhaps Fortran 90 or Fortran 95. The goal of MPI-3 should have been to ensure that new programs used the mpi or mpi_f08 modules and that existing programs could continue to be used. That is *not* the situation that we have now. Fair enough; but note that this has been true since 1996 (MPI_SIZEOF was introduced in MPI 2.0). > As far as I can tell from the requirement that MPI_SIZEOF be supported, mpif.h also requires Fortran 2008 + TS29113, meaning that many legacy MPI programs cannot be compiled with a standard conforming MPI implementation and a Fortran compiler that implements only, say, Fortran 2008 (but not the TS29113, which is *not* part of the standard) or Fortran 2003. Is 2003 or 2008+TS29113 required for SIZEOF? I have no knowledge of when INTERFACE blocks were added to Fortran. I'm asking this because DIMENSION(..) is *useful* to implement MPI_SIZEOF succinctly/easily, but it is not *required*. Put differently: if 2003/2008+TS is required for MPI_SIZEOF, then MPI-2.0 made a terrible error in defining MPI_SIZEOF. -- Jeff Squyres jsquyres(a)cisco.com For corporate legal information go to: http://www.cisco.com/web/about/doing_business/legal/cri/

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Re: [MPIWG Fortran] Another MPI_SIZEOF question
by Rolf Rabenseifner 10 Jun '14

10 Jun '14

> As far as I can tell from the > requirement that MPI_SIZEOF be supported, mpif.h also requires > Fortran 2008 + TS29113, meaning that many legacy MPI programs cannot > be compiled with a standard conforming MPI implementation and a > Fortran compiler that implements only, say, Fortran 2008 (but not > the TS29113, which is *not* part of the standard) or Fortran 2003. Section 17.1.6 on page 609 "MPI for Different Fortran Standard Versions" tries to define the rules for standard compliant MPI-3.0 with a Fortran 77, 90, 95, 2003, and 2003/2008+TS29113 compiler, i.e., MPI-3.0 can be implemented with the restrictions, e.g., MPI_SUBARRAYS_SUPPORTED needs to be set to .FALSE.. Rolf ----- Original Message ----- > From: "William Gropp" <wgropp(a)illinois.edu> > To: "MPI-WG Fortran working group" <mpiwg-fortran(a)lists.mpi-forum.org> > Sent: Tuesday, June 10, 2014 3:06:08 PM > Subject: Re: [MPIWG Fortran] Another MPI_SIZEOF question > > > This naming corresponds to MPI-3 but not to the use in MPI-1 nor to > what some users may still want, which is what Jeff is talking about. > > > > And note: When the original MPI Fortran interface was defined, it was > known not to be standard conformant - in fact, I raised that issue > and raised a straw man alternative that was not accepted by the MPI > Forum. The fact at the time was that it was widely recognized that > Fortran's (meaning Fortran 77) strict rules with the absence of any > escape combined with no real general data mechanism, needed by many > different libraries, not just MPI, made the type checking rules > impractical, and virtually no compiler of the time implemented this > check (the only one I knew of was WATFOR, and you could turn it > off). > > > Despite this, many applications were written using Fortran. Those > applications in practice, despite not conforming to the letter of > the standard, were portable and contributed to the success of MPI. > I don't find comments about "MPI never supported Fortran" to be > useful, even if they are technically true. > > > In my opinion, the use of "mpif.h" should have been to support > existing programs in their existing compilation environments. That > might be fixed-format early Fortran, either Fortran 77 or perhaps > Fortran 90 or Fortran 95. The goal of MPI-3 should have been to > ensure that new programs used the mpi or mpi_f08 modules and that > existing programs could continue to be used. That is *not* the > situation that we have now. As far as I can tell from the > requirement that MPI_SIZEOF be supported, mpif.h also requires > Fortran 2008 + TS29113, meaning that many legacy MPI programs cannot > be compiled with a standard conforming MPI implementation and a > Fortran compiler that implements only, say, Fortran 2008 (but not > the TS29113, which is *not* part of the standard) or Fortran 2003. > > > Bill > > > > > > > William Gropp > Director, Parallel Computing Institute Thomas M. Siebel Chair in > Computer Science > > > University of Illinois Urbana-Champaign > > > > > > > > On Jun 10, 2014, at 2:44 PM, Jeff Squyres (jsquyres) wrote: > > > > On Jun 10, 2014, at 8:35 AM, Jeff Hammond < jeff.science(a)gmail.com > > wrote: > > > > What shorthand will you permit for what is meant when Bill and I > refer > > > to Fortran 77 support in MPI that distinguishes it from F90 and F08 > > > module support? > > I usually say "the mpif.h interface", "the (Fortran) mpi module", and > "the mpi_f08 module". Indeed, I have renamed the "ompi/mpi/f77" and > "ompi/mpi/f90" directories from previous versions of OMPI to > "ompi/mpi/fortran/mpifh" and "ompi/mpi/fortran/use-mpi". > > Meaning: I have seen the error of my ways and corrected myself. You > can, too. :-) > > -- > Jeff Squyres > jsquyres(a)cisco.com > For corporate legal information go to: > http://www.cisco.com/web/about/doing_business/legal/cri/ > > _______________________________________________ > mpiwg-fortran mailing list > mpiwg-fortran(a)lists.mpi-forum.org > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-fortran > > > _______________________________________________ > mpiwg-fortran mailing list > mpiwg-fortran(a)lists.mpi-forum.org > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-fortran -- Dr. Rolf Rabenseifner . . . . . . . . . .. email rabenseifner(a)hlrs.de High Performance Computing Center (HLRS) . phone ++49(0)711/685-65530 University of Stuttgart . . . . . . . . .. fax ++49(0)711 / 685-65832 Head of Dpmt Parallel Computing . . . www.hlrs.de/people/rabenseifner Nobelstr. 19, D-70550 Stuttgart, Germany . . . . (Office: Room 1.307)

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Re: [MPIWG Fortran] Another MPI_SIZEOF question
by Jeff Hammond 10 Jun '14

10 Jun '14

>>> What shorthand will you permit for what is meant when Bill and I refer >>> to Fortran 77 support in MPI that distinguishes it from F90 and F08 >>> module support? >> >> I usually say "the mpif.h interface", "the (Fortran) mpi module", and "the mpi_f08 module". Indeed, I have renamed the "ompi/mpi/f77" and "ompi/mpi/f90" directories from previous versions of OMPI to "ompi/mpi/fortran/mpifh" and "ompi/mpi/fortran/use-mpi”. > > Indeed, this makes sense. You cannot include mpif.h and USE an mpi module in the same program unit, so these are the things that are mutually exclusive. Because the current Fortran standard includes (almost all of) the features in previous standards, trying to identify differences based on old standard names is much less precise. Sure, but 'mpif' doesn't indicate that it requires certain MPI features when used in conjunction with a Fortran compiler that lacks one or more F08 features. If someone was silly enough to use mpif+f08, they wouldn't need MPI_SIZEOF. I am trying to come up with a term that denotes mpif+pre-F08. Will I be permitted to say mpif+f90 to indicate the oldest variant of MPI Fortran support? Jeff -- Jeff Hammond jeff.science(a)gmail.com http://jeffhammond.github.io/

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Re: [MPIWG Fortran] Another MPI_SIZEOF question
by William Gropp 10 Jun '14

10 Jun '14

This naming corresponds to MPI-3 but not to the use in MPI-1 nor to what some users may still want, which is what Jeff is talking about. And note: When the original MPI Fortran interface was defined, it was known not to be standard conformant - in fact, I raised that issue and raised a straw man alternative that was not accepted by the MPI Forum. The fact at the time was that it was widely recognized that Fortran's (meaning Fortran 77) strict rules with the absence of any escape combined with no real general data mechanism, needed by many different libraries, not just MPI, made the type checking rules impractical, and virtually no compiler of the time implemented this check (the only one I knew of was WATFOR, and you could turn it off). Despite this, many applications were written using Fortran. Those applications in practice, despite not conforming to the letter of the standard, were portable and contributed to the success of MPI. I don't find comments about "MPI never supported Fortran" to be useful, even if they are technically true. In my opinion, the use of "mpif.h" should have been to support existing programs in their existing compilation environments. That might be fixed-format early Fortran, either Fortran 77 or perhaps Fortran 90 or Fortran 95. The goal of MPI-3 should have been to ensure that new programs used the mpi or mpi_f08 modules and that existing programs could continue to be used. That is *not* the situation that we have now. As far as I can tell from the requirement that MPI_SIZEOF be supported, mpif.h also requires Fortran 2008 + TS29113, meaning that many legacy MPI programs cannot be compiled with a standard conforming MPI implementation and a Fortran compiler that implements only, say, Fortran 2008 (but not the TS29113, which is *not* part of the standard) or Fortran 2003. Bill William Gropp Director, Parallel Computing Institute Thomas M. Siebel Chair in Computer Science University of Illinois Urbana-Champaign On Jun 10, 2014, at 2:44 PM, Jeff Squyres (jsquyres) wrote: > On Jun 10, 2014, at 8:35 AM, Jeff Hammond <jeff.science(a)gmail.com> wrote: > >> What shorthand will you permit for what is meant when Bill and I refer >> to Fortran 77 support in MPI that distinguishes it from F90 and F08 >> module support? > > I usually say "the mpif.h interface", "the (Fortran) mpi module", and "the mpi_f08 module". Indeed, I have renamed the "ompi/mpi/f77" and "ompi/mpi/f90" directories from previous versions of OMPI to "ompi/mpi/fortran/mpifh" and "ompi/mpi/fortran/use-mpi". > > Meaning: I have seen the error of my ways and corrected myself. You can, too. :-) > > -- > Jeff Squyres > jsquyres(a)cisco.com > For corporate legal information go to: http://www.cisco.com/web/about/doing_business/legal/cri/ > > _______________________________________________ > mpiwg-fortran mailing list > mpiwg-fortran(a)lists.mpi-forum.org > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-fortran

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Re: [MPIWG Fortran] Another MPI_SIZEOF question
by Bill Long 10 Jun '14

10 Jun '14

On Jun 10, 2014, at 7:44 AM, Jeff Squyres (jsquyres) <jsquyres(a)cisco.com> wrote: > On Jun 10, 2014, at 8:35 AM, Jeff Hammond <jeff.science(a)gmail.com> wrote: > >> What shorthand will you permit for what is meant when Bill and I refer >> to Fortran 77 support in MPI that distinguishes it from F90 and F08 >> module support? > > I usually say "the mpif.h interface", "the (Fortran) mpi module", and "the mpi_f08 module". Indeed, I have renamed the "ompi/mpi/f77" and "ompi/mpi/f90" directories from previous versions of OMPI to "ompi/mpi/fortran/mpifh" and "ompi/mpi/fortran/use-mpi”. Indeed, this makes sense. You cannot include mpif.h and USE an mpi module in the same program unit, so these are the things that are mutually exclusive. Because the current Fortran standard includes (almost all of) the features in previous standards, trying to identify differences based on old standard names is much less precise. Cheers, Bill > > > Meaning: I have seen the error of my ways and corrected myself. You can, too. :-) > > -- > Jeff Squyres > jsquyres(a)cisco.com > For corporate legal information go to: http://www.cisco.com/web/about/doing_business/legal/cri/ > > _______________________________________________ > mpiwg-fortran mailing list > mpiwg-fortran(a)lists.mpi-forum.org > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-fortran Bill Long longb(a)cray.com Fortran Technical Suport & voice: 651-605-9024 Bioinformatics Software Development fax: 651-605-9142 Cray Inc./ Cray Plaza, Suite 210/ 380 Jackson St./ St. Paul, MN 55101

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