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Re: [Mpi-22] Another MPI-2.2 attribute ambiguity?
by unknown＠example.com 22 May '09

22 May '09

Imagine a Fortran communicator keyval copy function callback like this (typed off the top of my head; pardon typos): SUBROUTINE COPY_FUNCTION1(OLDCOMM, KEYVAL, EXTRA_STATE, AVALIN, AVALOUT, FLAG, IERR) ... INTEGER EXTRA_STATE INTEGER IERR EXTRA_STATE = EXTRA_STATE + 1 WRITE *, "Extra state is: ", EXTRA_STATE IERR = MPI_SUCCESS END Now suppose MPI_COMM_CREATE_KEYVAL is invoked like this: INTEGER EV = 7 CALL MPI_COMM_KEYVAL_CREATE(COPY_FUNCTION1, ..., EV, IERR) I think we all agree that the output the first time that COPY_FUNCTION1 is invoked should be 7. But what is the output the second time it is invoked -- 7 or 8? That is the question. I think Iain has conclusively show that in this case: INTEGER EV = 7 CALL MPI_COMM_KEYVAL_CREATE(COPY_FUNCTION1, ..., EV + 3, IERR) EV = 42 the output from the first call to COPY_FUNCTION1 still needs to be 10. The point is that the MPI implementation needs to *copy* the INTEGER value into internal storage and use *that* storage when calling COPY_FUNCTION1. If for no other reason than the value may be the result of an expression, and that storage disappears after the call to MPI_COMM_KEYVAL_CREATE completes (as in the above example). I'm not sure what you're referring to with the array stuff -- the Fortran prototype for the callback function says that the extra value can only be a single INTEGER...? On May 21, 2009, at 4:41 PM, William Gropp wrote: > I'm not sure what "change the value" means in #1. I think that you > mean "if we interpret extra_data as a pointer to a Fortran data item, > the MPI implementation will pass this pointer (by value) to the > callback. If the callback stores through this pointer, then > (naturally) the afore mentioned data item will be changed. If that's > what #1 means, then yes, that's the right answer. Note that the > extra_data could be a pointer to an array of arbitrary size, and the > call back could update any part of the array. Saving a copy of what > extra_data points at (is that what #2 is doing?) is going to be > tricky, since you don't know the size of the thing to copy (without a > lot of help from the compiler in Fortran). > > Bill > > On May 19, 2009, at 7:55 PM, Jeff Squyres wrote: > > > So then you're in favor of #1 from my original post, right? > > > > http://lists.mpi-forum.org/mpi-22/2009/05/0407.php > > > > > > On May 19, 2009, at 4:39 PM, William Gropp wrote: > > > >> Silly me, I missed that. > >> > >> In Fortran (particularly thinking in terms of Fortran 77, since > that > >> was the original design), the Fortran callback should be able to do > >> things like increment the "extra data" - i.e., if the extra data > is a > >> counter, the Fortran callback should be able to increment it. > Since > >> Fortran 77 has no pointers (and pointers in Fortran 90 aren't the > >> same > >> as addresses), having an address is worthless in a Fortran 77 > >> program. So if the MPI implementation stores the address of the > >> extra > >> data and passes that to the call back (by value, so Fortran sees > the > >> address of the extra data), users should get what they expect in > >> Fortran. > >> > >> Bill > >> > >> On May 19, 2009, at 12:22 PM, Iain Bason wrote: > >> > >>> > >>> On May 19, 2009, at 1:16 PM, William Gropp wrote: > >>> > >>>> MPICH2 passes the value of the extra_state that was saved in the > >>>> internal storage to the callback routine, which is case 2 (the > copy > >>>> is implicit as the value is passed to the routine and C semantics > >>>> ensures that the value isn't changed). > >>> > >>> But this is the Fortran interface, not the C interface. > >>> > >>> Iain > >>> > >> > >> William Gropp > >> Deputy Director for Research > >> Institute for Advanced Computing Applications and Technologies > >> Paul and Cynthia Saylor Professor of Computer Science > >> University of Illinois Urbana-Champaign > >> > >> > >> > >> > >> _______________________________________________ > >> mpi-22 mailing list > >> mpi-22_at_[hidden] > >> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi-22 > >> > > > > > > -- > > Jeff Squyres > > Cisco Systems > > > > _______________________________________________ > > mpi-22 mailing list > > mpi-22_at_[hidden] > > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi-22 > > William Gropp > Deputy Director for Research > Institute for Advanced Computing Applications and Technologies > Paul and Cynthia Saylor Professor of Computer Science > University of Illinois Urbana-Champaign > > > > > _______________________________________________ > mpi-22 mailing list > mpi-22_at_[hidden] > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi-22 > -- Jeff Squyres Cisco Systems

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Re: [Mpi-22] Another MPI-2.2 attribute ambiguity?
by unknown＠example.com 21 May '09

21 May '09

I'm not sure what "change the value" means in #1. I think that you mean "if we interpret extra_data as a pointer to a Fortran data item, the MPI implementation will pass this pointer (by value) to the callback. If the callback stores through this pointer, then (naturally) the afore mentioned data item will be changed. If that's what #1 means, then yes, that's the right answer. Note that the extra_data could be a pointer to an array of arbitrary size, and the call back could update any part of the array. Saving a copy of what extra_data points at (is that what #2 is doing?) is going to be tricky, since you don't know the size of the thing to copy (without a lot of help from the compiler in Fortran). Bill On May 19, 2009, at 7:55 PM, Jeff Squyres wrote: > So then you're in favor of #1 from my original post, right? > > http://lists.mpi-forum.org/mpi-22/2009/05/0407.php > > > On May 19, 2009, at 4:39 PM, William Gropp wrote: > >> Silly me, I missed that. >> >> In Fortran (particularly thinking in terms of Fortran 77, since that >> was the original design), the Fortran callback should be able to do >> things like increment the "extra data" - i.e., if the extra data is a >> counter, the Fortran callback should be able to increment it. Since >> Fortran 77 has no pointers (and pointers in Fortran 90 aren't the >> same >> as addresses), having an address is worthless in a Fortran 77 >> program. So if the MPI implementation stores the address of the >> extra >> data and passes that to the call back (by value, so Fortran sees the >> address of the extra data), users should get what they expect in >> Fortran. >> >> Bill >> >> On May 19, 2009, at 12:22 PM, Iain Bason wrote: >> >>> >>> On May 19, 2009, at 1:16 PM, William Gropp wrote: >>> >>>> MPICH2 passes the value of the extra_state that was saved in the >>>> internal storage to the callback routine, which is case 2 (the copy >>>> is implicit as the value is passed to the routine and C semantics >>>> ensures that the value isn't changed). >>> >>> But this is the Fortran interface, not the C interface. >>> >>> Iain >>> >> >> William Gropp >> Deputy Director for Research >> Institute for Advanced Computing Applications and Technologies >> Paul and Cynthia Saylor Professor of Computer Science >> University of Illinois Urbana-Champaign >> >> >> >> >> _______________________________________________ >> mpi-22 mailing list >> mpi-22_at_[hidden] >> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi-22 >> > > > -- > Jeff Squyres > Cisco Systems > > _______________________________________________ > mpi-22 mailing list > mpi-22_at_[hidden] > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi-22 William Gropp Deputy Director for Research Institute for Advanced Computing Applications and Technologies Paul and Cynthia Saylor Professor of Computer Science University of Illinois Urbana-Champaign

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Re: [Mpi-22] Another MPI-2.2 attribute ambiguity?
by unknown＠example.com 20 May '09

20 May '09

On May 20, 2009, at 10:53 AM, Jeff Squyres (jsquyres) wrote: > - Open MPI's upcoming v1.3.3 currently does #1 > - Platform (Scali) MPI does #1 > - HP MPI does #2 > - I *think* MPICH2 is doing #1 (Bill's text can be interpreted 2 ways, > but we already discussed that it's not valid to keep the address of > the value passed through MPI_*_CREATE_KEYVAL) > - Alexander said that Intel MPI does the same thing as Bill's original > reply, but I'm not sure what that means (because Bill's original reply > was about C) > - NEC MPI does #1. -- Jeff Squyres Cisco Systems

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Re: [Mpi-22] Another MPI-2.2 attribute ambiguity?
by unknown＠example.com 20 May '09

20 May '09

On May 19, 2009, at 8:55 PM, Jeff Squyres (jsquyres) wrote: > So then you're in favor of #1 from my original post, right? > > http://lists.mpi-forum.org/mpi-22/2009/05/0407.php > To be even more clear: - Open MPI's upcoming v1.3.3 currently does #1 - Platform (Scali) MPI does #1 - HP MPI does #2 - I *think* MPICH2 is doing #1 (Bill's text can be interpreted 2 ways, but we already discussed that it's not valid to keep the address of the value passed through MPI_*_CREATE_KEYVAL) - Alexander said that Intel MPI does the same thing as Bill's original reply, but I'm not sure what that means (because Bill's original reply was about C) I don't know what IBM MPI, NEC MPI, or others do (I assume MS MPI and MVAPICH do the same thing as MPICH2). > On May 19, 2009, at 4:39 PM, William Gropp wrote: > > > Silly me, I missed that. > > > > In Fortran (particularly thinking in terms of Fortran 77, since that > > was the original design), the Fortran callback should be able to do > > things like increment the "extra data" - i.e., if the extra data > is a > > counter, the Fortran callback should be able to increment it. Since > > Fortran 77 has no pointers (and pointers in Fortran 90 aren't the > same > > as addresses), having an address is worthless in a Fortran 77 > > program. So if the MPI implementation stores the address of the > extra > > data and passes that to the call back (by value, so Fortran sees the > > address of the extra data), users should get what they expect in > > Fortran. > > > > Bill > > > > On May 19, 2009, at 12:22 PM, Iain Bason wrote: > > > > > > > > On May 19, 2009, at 1:16 PM, William Gropp wrote: > > > > > >> MPICH2 passes the value of the extra_state that was saved in the > > >> internal storage to the callback routine, which is case 2 (the > copy > > >> is implicit as the value is passed to the routine and C semantics > > >> ensures that the value isn't changed). > > > > > > But this is the Fortran interface, not the C interface. > > > > > > Iain > > > > > > > William Gropp > > Deputy Director for Research > > Institute for Advanced Computing Applications and Technologies > > Paul and Cynthia Saylor Professor of Computer Science > > University of Illinois Urbana-Champaign > > > > > > > > > > _______________________________________________ > > mpi-22 mailing list > > mpi-22_at_[hidden] > > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi-22 > > > > > -- > Jeff Squyres > Cisco Systems > > _______________________________________________ > mpi-22 mailing list > mpi-22_at_[hidden] > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi-22 > -- Jeff Squyres Cisco Systems

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Re: [Mpi-22] Another MPI-2.2 attribute ambiguity?
by unknown＠example.com 19 May '09

19 May '09

So then you're in favor of #1 from my original post, right? http://lists.mpi-forum.org/mpi-22/2009/05/0407.php On May 19, 2009, at 4:39 PM, William Gropp wrote: > Silly me, I missed that. > > In Fortran (particularly thinking in terms of Fortran 77, since that > was the original design), the Fortran callback should be able to do > things like increment the "extra data" - i.e., if the extra data is a > counter, the Fortran callback should be able to increment it. Since > Fortran 77 has no pointers (and pointers in Fortran 90 aren't the same > as addresses), having an address is worthless in a Fortran 77 > program. So if the MPI implementation stores the address of the extra > data and passes that to the call back (by value, so Fortran sees the > address of the extra data), users should get what they expect in > Fortran. > > Bill > > On May 19, 2009, at 12:22 PM, Iain Bason wrote: > > > > > On May 19, 2009, at 1:16 PM, William Gropp wrote: > > > >> MPICH2 passes the value of the extra_state that was saved in the > >> internal storage to the callback routine, which is case 2 (the copy > >> is implicit as the value is passed to the routine and C semantics > >> ensures that the value isn't changed). > > > > But this is the Fortran interface, not the C interface. > > > > Iain > > > > William Gropp > Deputy Director for Research > Institute for Advanced Computing Applications and Technologies > Paul and Cynthia Saylor Professor of Computer Science > University of Illinois Urbana-Champaign > > > > > _______________________________________________ > mpi-22 mailing list > mpi-22_at_[hidden] > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi-22 > -- Jeff Squyres Cisco Systems

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Re: [Mpi-22] Another MPI-2.2 attribute ambiguity?
by unknown＠example.com 19 May '09

19 May '09

Silly me, I missed that. In Fortran (particularly thinking in terms of Fortran 77, since that was the original design), the Fortran callback should be able to do things like increment the "extra data" - i.e., if the extra data is a counter, the Fortran callback should be able to increment it. Since Fortran 77 has no pointers (and pointers in Fortran 90 aren't the same as addresses), having an address is worthless in a Fortran 77 program. So if the MPI implementation stores the address of the extra data and passes that to the call back (by value, so Fortran sees the address of the extra data), users should get what they expect in Fortran. Bill On May 19, 2009, at 12:22 PM, Iain Bason wrote: > > On May 19, 2009, at 1:16 PM, William Gropp wrote: > >> MPICH2 passes the value of the extra_state that was saved in the >> internal storage to the callback routine, which is case 2 (the copy >> is implicit as the value is passed to the routine and C semantics >> ensures that the value isn't changed). > > But this is the Fortran interface, not the C interface. > > Iain > William Gropp Deputy Director for Research Institute for Advanced Computing Applications and Technologies Paul and Cynthia Saylor Professor of Computer Science University of Illinois Urbana-Champaign

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Re: [Mpi-22] Another MPI-2.2 attribute ambiguity?
by unknown＠example.com 19 May '09

19 May '09

On May 19, 2009, at 1:16 PM, William Gropp wrote: > MPICH2 passes the value of the extra_state that was saved in the > internal storage to the callback routine, which is case 2 (the copy > is implicit as the value is passed to the routine and C semantics > ensures that the value isn't changed). But this is the Fortran interface, not the C interface. Iain

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Re: [Mpi-22] Another MPI-2.2 attribute ambiguity?
by unknown＠example.com 19 May '09

19 May '09

MPICH2 passes the value of the extra_state that was saved in the internal storage to the callback routine, which is case 2 (the copy is implicit as the value is passed to the routine and C semantics ensures that the value isn't changed). Bill On May 18, 2009, at 10:24 AM, Jeff Squyres wrote: > I'm most curious to know what current MPI implementations do in this > scenario. > > > On May 14, 2009, at 1:05 PM, Jeff Squyres wrote: > >> Another question about this issue... >> >> Since all fortran values are passed by reference, does the MPI care >> if the callback function changes the EXTRA_STATE value? I see 2 >> choices: >> >> 1. The MPI copies the value of extra_state when MPI_*_CREATE_KEVAL >> is invoked to internal storage. This internal storage is passed to >> all the callbacks when invoked. If any of the callbacks change the >> value, then subsequent invocations of the callback get the changed >> value. >> >> 2. The MPI copies the value of extra_state when MPI_*_CREATE_KEVAL >> is invoked to internal storage. This internal storage is copied any >> time a callback is invoked; the copy is passed to the callback (and >> freed when the callback returns). In this way, the same EXTRA_STATE >> value that was originally passed to the keyval constructor will >> always be passed to any callbacks. >> >> What do current MPI implementations do? >> >> OMPI's development trunk has been updated to do #1; I'm wondering if >> it should do #2. >> >> >> >> On Apr 17, 2009, at 10:21 AM, Jeff Squyres (jsquyres) wrote: >> >>> Ok, I'll file an MPI-3 ticket for this. >>> >>> (for everyone else on the 2.2 list wondering why you just got >>> blitzkrieged with a whole pile of emails on this topic: the >>> listserver >>> sent all these mails to moderation because of the lengthy CC list. >>> IU >>> just approved all the mails to go through this morning) >>> >>> >>> On Apr 17, 2009, at 9:40 AM, William Gropp wrote: >>> >>>> Yes, this is worth an ATI - the fact that we traded this much >>> mail on >>>> it is proof of that :) >>>> >>>> Thanks, Jeff. >>>> >>>> Bill >>>> >>>> On Apr 17, 2009, at 8:14 AM, Jeff Squyres wrote: >>>> >>>>> Someone pointed out to me this morning that there's no >>> restriction >>>> on >>>>> the value of EXTRA_STATE when CREATE_KEYVAL is invoked -- it may >>>> be an >>>>> expression, for example. I think that pretty much seals the deal >>>> that >>>>> #2 is the correct way. >>>>> >>>>> I think that this is worth an ATI in the text; does anyone >>> disagree? >>>>> I volunteer to write it up/make a 3.0 ticket (hey, first ticket >>> for >>>>> the Misc WG! :-) ) if no one disagrees. >>>>> >>>>> >>>>> On Apr 17, 2009, at 8:59 AM, Supalov, Alexander wrote: >>>>> >>>>>> Hi, >>>>>> >>>>>> Intel MPI (and most likely other MPICH2 derivatives) appears >>> to use >>>>>> method #2. >>>>>> >>>>>> Best regards. >>>>>> >>>>>> Alexander >>>>>> >>>>>> -----Original Message----- >>>>>> From: Jeff Squyres [mailto:jsquyres_at_[hidden]] >>>>>> Sent: Thursday, April 16, 2009 4:19 PM >>>>>> To: MPI 2.2; Rajeev Thakur; William Gropp; Rolf Rabenseifner; >>>> Hubert >>>>>> Ritzdorf; Terry Dontje; Dave Goodell; Darius Buntinas; Pavan >>>> Balaji; >>>>>> Supalov, Alexander; Bronis de Supinski; David Solt; Hans >>> Westgaard >>>>>> Ry; Håkon Bugge >>>>>> Subject: Another MPI-2.2 attribute ambiguity? >>>>>> >>>>>> This is related to -- but different from -- MPI 2.2 ticket #55 >>>>>> ("MPI-2.1 Cross-language attribute example is wrong"). >>> Explicitly >>>>>> adding all the #55 CC members to this mail, plus a few others. >>>>>> >>>>>> I cannot find any text in MPI-2.1 (e.g., p223-225) describing >>>>>> specific >>>>>> behavior regarding the EXTRA_STATE arguments passed to the >>> Fortran >>>>>> keyval copy and delete functions (both the ADDRESS_KIND and >>>>>> deprecated >>>>>> flavors). I see two choices: >>>>>> >>>>>> 1. pass the user's original EXTRA_STATE argument by reference to >>>> the >>>>>> callbacks, or >>>>>> 2. copy the user's original EXTRA_STATE into internal MPI >>> storage >>>> and >>>>>> pass *that* value by reference to the callbacks >>>>>> >>>>>> ==> Open MPI currently does #1. What do other implementations >>> do? >>>>>> >>>>>> I raise this issue because the text does not indicate which >>> way is >>>>>> right. And I just ran across an old Sun test that assumed >>> #2. But >>>>>> our internal copy of the Intel MPI tests assume #1 (to be >>> fair: I >>>>>> have >>>>>> no idea if the Intel tests originally assumed #2 and we changed >>>> them >>>>>> to #1 over time). Indeed, #2 is actually in-line with the >>>> philosophy >>>>>> of storing attribute values in internal MPI storage. E.g.: >>>>>> >>>>>> INTEGER foo = 4 >>>>>> INTEGER bar >>>>>> CALL MPI_COMM_SET_ATTR(comm, keyval, foo, ierr) >>>>>> foo = 5 >>>>>> CALL MPI_COMM_GET_ATTR(comm, keyval, bar, flag, ierr) >>>>>> >>>>>> bar should equal 4, not 5 (right?). >>>>>> >>>>>> So what does that mean (or imply) about the EXTRA_STATE value >>>> passed >>>>>> to the Fortran callbacks? >>>>>> >>>>>> -- >>>>>> Jeff Squyres >>>>>> Cisco Systems >>>>>> >>>>>> >>>> >>> --------------------------------------------------------------------- >>>>>> Intel GmbH >>>>>> Dornacher Strasse 1 >>>>>> 85622 Feldkirchen/Muenchen Germany >>>>>> Sitz der Gesellschaft: Feldkirchen bei Muenchen >>>>>> Geschaeftsfuehrer: Douglas Lusk, Peter Gleissner, Hannes >>> Schwaderer >>>>>> Registergericht: Muenchen HRB 47456 Ust.-IdNr. >>>>>> VAT Registration No.: DE129385895 >>>>>> Citibank Frankfurt (BLZ 502 109 00) 600119052 >>>>>> >>>>>> This e-mail and any attachments may contain confidential >>> material >>>> for >>>>>> the sole use of the intended recipient(s). Any review or >>>> distribution >>>>>> by others is strictly prohibited. If you are not the intended >>>>>> recipient, please contact the sender and delete all copies. >>>>>> >>>>>> >>>>> >>>>> >>>>> -- >>>>> Jeff Squyres >>>>> Cisco Systems >>>>> >>>> >>>> William Gropp >>>> Deputy Director for Research >>>> Institute for Advanced Computing Applications and Technologies >>>> Paul and Cynthia Saylor Professor of Computer Science >>>> University of Illinois Urbana-Champaign >>>> >>>> >>>> >>>> >>> >>> >>> -- >>> Jeff Squyres >>> Cisco Systems >>> >>> >>> _______________________________________________ >>> mpi-22 mailing list >>> mpi-22_at_[hidden] >>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi-22 >> >> >> -- >> Jeff Squyres >> Cisco Systems >> >> >> _______________________________________________ >> mpi-22 mailing list >> mpi-22_at_[hidden] >> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi-22 > > > -- > Jeff Squyres > Cisco Systems > > > _______________________________________________ > mpi-22 mailing list > mpi-22_at_[hidden] > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi-22 William Gropp Deputy Director for Research Institute for Advanced Computing Applications and Technologies Paul and Cynthia Saylor Professor of Computer Science University of Illinois Urbana-Champaign

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Re: [Mpi-22] Another MPI-2.2 attribute ambiguity?
by unknown＠example.com 18 May '09

18 May '09

I'm most curious to know what current MPI implementations do in this scenario. On May 14, 2009, at 1:05 PM, Jeff Squyres wrote: > Another question about this issue... > > Since all fortran values are passed by reference, does the MPI care > if the callback function changes the EXTRA_STATE value? I see 2 > choices: > > 1. The MPI copies the value of extra_state when MPI_*_CREATE_KEVAL > is invoked to internal storage. This internal storage is passed to > all the callbacks when invoked. If any of the callbacks change the > value, then subsequent invocations of the callback get the changed > value. > > 2. The MPI copies the value of extra_state when MPI_*_CREATE_KEVAL > is invoked to internal storage. This internal storage is copied any > time a callback is invoked; the copy is passed to the callback (and > freed when the callback returns). In this way, the same EXTRA_STATE > value that was originally passed to the keyval constructor will > always be passed to any callbacks. > > What do current MPI implementations do? > > OMPI's development trunk has been updated to do #1; I'm wondering if > it should do #2. > > > > On Apr 17, 2009, at 10:21 AM, Jeff Squyres (jsquyres) wrote: > >> Ok, I'll file an MPI-3 ticket for this. >> >> (for everyone else on the 2.2 list wondering why you just got >> blitzkrieged with a whole pile of emails on this topic: the >> listserver >> sent all these mails to moderation because of the lengthy CC list. >> IU >> just approved all the mails to go through this morning) >> >> >> On Apr 17, 2009, at 9:40 AM, William Gropp wrote: >> >> > Yes, this is worth an ATI - the fact that we traded this much >> mail on >> > it is proof of that :) >> > >> > Thanks, Jeff. >> > >> > Bill >> > >> > On Apr 17, 2009, at 8:14 AM, Jeff Squyres wrote: >> > >> > > Someone pointed out to me this morning that there's no >> restriction >> > on >> > > the value of EXTRA_STATE when CREATE_KEYVAL is invoked -- it may >> > be an >> > > expression, for example. I think that pretty much seals the deal >> > that >> > > #2 is the correct way. >> > > >> > > I think that this is worth an ATI in the text; does anyone >> disagree? >> > > I volunteer to write it up/make a 3.0 ticket (hey, first ticket >> for >> > > the Misc WG! :-) ) if no one disagrees. >> > > >> > > >> > > On Apr 17, 2009, at 8:59 AM, Supalov, Alexander wrote: >> > > >> > >> Hi, >> > >> >> > >> Intel MPI (and most likely other MPICH2 derivatives) appears >> to use >> > >> method #2. >> > >> >> > >> Best regards. >> > >> >> > >> Alexander >> > >> >> > >> -----Original Message----- >> > >> From: Jeff Squyres [mailto:jsquyres_at_[hidden]] >> > >> Sent: Thursday, April 16, 2009 4:19 PM >> > >> To: MPI 2.2; Rajeev Thakur; William Gropp; Rolf Rabenseifner; >> > Hubert >> > >> Ritzdorf; Terry Dontje; Dave Goodell; Darius Buntinas; Pavan >> > Balaji; >> > >> Supalov, Alexander; Bronis de Supinski; David Solt; Hans >> Westgaard >> > >> Ry; Håkon Bugge >> > >> Subject: Another MPI-2.2 attribute ambiguity? >> > >> >> > >> This is related to -- but different from -- MPI 2.2 ticket #55 >> > >> ("MPI-2.1 Cross-language attribute example is wrong"). >> Explicitly >> > >> adding all the #55 CC members to this mail, plus a few others. >> > >> >> > >> I cannot find any text in MPI-2.1 (e.g., p223-225) describing >> > >> specific >> > >> behavior regarding the EXTRA_STATE arguments passed to the >> Fortran >> > >> keyval copy and delete functions (both the ADDRESS_KIND and >> > >> deprecated >> > >> flavors). I see two choices: >> > >> >> > >> 1. pass the user's original EXTRA_STATE argument by reference to >> > the >> > >> callbacks, or >> > >> 2. copy the user's original EXTRA_STATE into internal MPI >> storage >> > and >> > >> pass *that* value by reference to the callbacks >> > >> >> > >> ==> Open MPI currently does #1. What do other implementations >> do? >> > >> >> > >> I raise this issue because the text does not indicate which >> way is >> > >> right. And I just ran across an old Sun test that assumed >> #2. But >> > >> our internal copy of the Intel MPI tests assume #1 (to be >> fair: I >> > >> have >> > >> no idea if the Intel tests originally assumed #2 and we changed >> > them >> > >> to #1 over time). Indeed, #2 is actually in-line with the >> > philosophy >> > >> of storing attribute values in internal MPI storage. E.g.: >> > >> >> > >> INTEGER foo = 4 >> > >> INTEGER bar >> > >> CALL MPI_COMM_SET_ATTR(comm, keyval, foo, ierr) >> > >> foo = 5 >> > >> CALL MPI_COMM_GET_ATTR(comm, keyval, bar, flag, ierr) >> > >> >> > >> bar should equal 4, not 5 (right?). >> > >> >> > >> So what does that mean (or imply) about the EXTRA_STATE value >> > passed >> > >> to the Fortran callbacks? >> > >> >> > >> -- >> > >> Jeff Squyres >> > >> Cisco Systems >> > >> >> > >> >> > >> --------------------------------------------------------------------- >> > >> Intel GmbH >> > >> Dornacher Strasse 1 >> > >> 85622 Feldkirchen/Muenchen Germany >> > >> Sitz der Gesellschaft: Feldkirchen bei Muenchen >> > >> Geschaeftsfuehrer: Douglas Lusk, Peter Gleissner, Hannes >> Schwaderer >> > >> Registergericht: Muenchen HRB 47456 Ust.-IdNr. >> > >> VAT Registration No.: DE129385895 >> > >> Citibank Frankfurt (BLZ 502 109 00) 600119052 >> > >> >> > >> This e-mail and any attachments may contain confidential >> material >> > for >> > >> the sole use of the intended recipient(s). Any review or >> > distribution >> > >> by others is strictly prohibited. If you are not the intended >> > >> recipient, please contact the sender and delete all copies. >> > >> >> > >> >> > > >> > > >> > > -- >> > > Jeff Squyres >> > > Cisco Systems >> > > >> > >> > William Gropp >> > Deputy Director for Research >> > Institute for Advanced Computing Applications and Technologies >> > Paul and Cynthia Saylor Professor of Computer Science >> > University of Illinois Urbana-Champaign >> > >> > >> > >> > >> >> >> -- >> Jeff Squyres >> Cisco Systems >> >> >> _______________________________________________ >> mpi-22 mailing list >> mpi-22_at_[hidden] >> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi-22 > > > -- > Jeff Squyres > Cisco Systems > > > _______________________________________________ > mpi-22 mailing list > mpi-22_at_[hidden] > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi-22 -- Jeff Squyres Cisco Systems

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Re: [Mpi-22] Another MPI-2.2 attribute ambiguity?
by unknown＠example.com 14 May '09

14 May '09

On May 14, 2009, at 1:05 PM, Jeff Squyres wrote: > Another question about this issue... > > Since all fortran values are passed by reference, does the MPI care > if the callback function changes the EXTRA_STATE value? I see 2 > choices: > > 1. The MPI copies the value of extra_state when MPI_*_CREATE_KEVAL > is invoked to internal storage. This internal storage is passed to > all the callbacks when invoked. If any of the callbacks change the > value, then subsequent invocations of the callback get the changed > value. > > 2. The MPI copies the value of extra_state when MPI_*_CREATE_KEVAL > is invoked to internal storage. This internal storage is copied any > time a callback is invoked; the copy is passed to the callback (and > freed when the callback returns). In this way, the same EXTRA_STATE > value that was originally passed to the keyval constructor will > always be passed to any callbacks. > > What do current MPI implementations do? > > OMPI's development trunk has been updated to do #1; I'm wondering if > it should do #2. I wondered about that too. I don't think that the Fortran standard has anything to say about it, so it's really a matter of what would be most useful to MPI users. Of course, if the MPI spec said that EXTRA_STATE was INTENT(IN) then there would be no ambiguity. Iain

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