[Mpi3-rma] FW: draft of a proposal for RMA interfaces
tipparajuv at hotmail.com
Tue Dec 9 07:51:42 CST 2008
> inside of GA, I have to manually do everything that ARMCI_Malloc did> previously?
yes the user has to. Do you think that is a bad idea?
> Will it be possible for RMA to distinguish between segments which are> locally allocated as shared versus private? Presumably, it is much
Certainly, the proposal mentions a memory attribute to inform the MPI implementation of any special memory like say preregistered memory.
Vinod.> Date: Mon, 8 Dec 2008 13:55:16 -0600> From: jeff.science at gmail.com> To: mpi3-rma at lists.mpi-forum.org> Subject: Re: [Mpi3-rma] FW: draft of a proposal for RMA interfaces> > I apologize in advance for potential noobiness...> > The GA user manual has an extensive discussion of the coupling between> GA, ARMCI and MA> (http://www.emsl.pnl.gov/docs/global/um/init.html#ma). If MPI3> one-sided communication replaces ARMCI as the messaging layer of GA,> what happens at the interface between these libraries? In particular,> in what way would the sentence "shared memory is used to store global> array data and is allocated by the Global Arrays run-time system> called ARMCI" change if "ARMCI" changes to "MPI3"?> > I imagine that it is not within the scope of MPI to start explicitly> managing local memory but does that mean that if I happen to get> inside of GA, I have to manually do everything that ARMCI_Malloc did> previously?> > Will it be possible for RMA to distinguish between segments which are> locally allocated as shared versus private? Presumably, it is much> harder to make RMA on shared segments thread safe and where one is> RMA-ing only between private segments then performance is increased in> the context of multithreading if the more rigorous locking procedure> used for the former is turned off.> > Thanks,> > Jeff> > On Mon, Dec 8, 2008 at 1:12 PM, Vinod tipparaju <tipparajuv at hotmail.com> wrote:> >> >> > As I am preparing the faq Rajeev suggested, please send me any more> > questions you want included.> > Thanks,> > Vinod.> >> > ________________________________> > From: thakur at mcs.anl.gov> > To: mpi3-rma at lists.mpi-forum.org> > Date: Mon, 8 Dec 2008 12:04:14 -0600> > Subject: [Mpi3-rma] FW: draft of a proposal for RMA interfaces> >> > Just resending this as a reminder. It would be good to have an FAQ that> > answers commonly asked questions.> >> > Rajeev> > ________________________________> > From: Rajeev Thakur [mailto:thakur at mcs.anl.gov]> > Sent: Sunday, October 19, 2008 6:43 PM> > To: 'MPI 3.0 Remote Memory Access working group'> > Subject: RE: [Mpi3-rma] draft of a proposal for RMA interfaces> >> > I think it would be good to add an FAQ section at the end, containing> > answers to questions that will be asked of any RMA proposal, such as> > non-cache-coherent, does it meet the needs of PGAS/Global Arrays, support> > for heterogeneous, how does the target know of completion, how does it> > interplay with existing RMA spec, etc. It will make sure that the proposal> > addresses those issues, that we ourselves are clear of the answers, and that> > they are not repeatedly raised at each meeting.> > Rajeev> >> >> Richard Graham wrote:> >>> >>> Just to get discussion going again. Talking with several folks I have> >>> heard several concerns expressed about the proposal. I think it would> >>> be good if these (and others) could be raised on the list, so we can> >>> start discussion. We can continue this next week in Chicago, but> >>> Vinod will not be able to make this meeting, so an e-mail discussion> >>> will help.> >>>> >>> Here are the issues I have hear of so far:> >>> - May not work well on current h/w that is not cache coherent, as it> >>> requires a remote thread in this case. I believe this is for the SX> >>> series of machines, but Jesper please correct me if I am wrong here.> >>> What would be an alternative approach that could provide expected> >>> performance on platforms that may require work on the remote end for> >>> RMA for correctness, and work well on platforms that do require very> >>> specific remote cache management (or other actions) for correctness ?> >>> - Concern about future high-end platforms, under that assumption that> >>> these will not be cache coherent (and will actually have caches – if> >>> they don't this is not a concern), and therefore this proposal is> >>> aimed at a short-lived technical capability.> >>> - What is missing ?> >> > _______________________________________________> > mpi3-rma mailing list> > mpi3-rma at lists.mpi-forum.org> > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma> >> >> > > > -- > Jeff Hammond> The University of Chicago> http://home.uchicago.edu/~jhammond/> > _______________________________________________> mpi3-rma mailing list> mpi3-rma at lists.mpi-forum.org> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma
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