Noted. Thanks again -- Sid
On 18 August 2013 18:40, Ralph Castain <r...@open-mpi.org> wrote: > It only has to come after MPI_Init *if* you are telling mpirun to bind you > as well. Otherwise, you could just not tell mpirun to bind (it doesn't by > default) and then bind anywhere, anytime you like > > > On Aug 18, 2013, at 3:24 PM, Siddhartha Jana <siddharthajan...@gmail.com> > wrote: > > > A process can always change its binding by "re-binding" to wherever it >> wants after MPI_Init completes. >> > Noted. Thanks. I guess the important thing that I wanted to know was that > the binding needs to happen *after* MPI_Init() completes. > > Thanks all > > -- Siddhartha > > > >> >> >> On Aug 18, 2013, at 9:38 AM, Siddhartha Jana <siddharthajan...@gmail.com> >> wrote: >> >> Firstly, I would like my program to dynamically assign it self to one of >> the cores it pleases and remain bound to it until it later reschedules >> itself. >> * >> >> Ralph Castain wrote:* >> *>> "If you just want mpirun to respect an external cpuset limitation, >> it already does so when binding - it will bind within the external >> limitation"* >> >> In my case, the limitation is enforced "internally", by the application >> once in begins execution. I enforce this during program execution, after >> the mpirun has finished "binding within the external limitation". >> >> >> *Brice Goglin said*: >> *>> "MPI can bind at two different times: inside mpirun after ssh >> before running the actual program (this one would ignore your cpuset), >> later at MPI_Init inside your program (this one will ignore your cpuset >> only if you call MPI_Init before creating the cpuset)."* >> >> Noted. In that case, during program execution, whose binding is respected >> - mpirun's or MPI_Init()'s? From the above, is my understanding correct? >> That MPI_Init() will be responsible for the 2nd round of attempting to bind >> processes to cores and can override what mpirun or the programmer had >> enforced before its call (using hwloc/cpuset/sched_load_balance()* *and >> other *compatible* cousins) ? >> >> >> -------------------------------------------- >> If this is so, in my case the flow of events is thus: >> >> 1. mpirun binds an MPI process which is yet to begin execution. So mpirun >> says: "Bind to some core - A" (I don't use any hostfile/rankfile. but I do >> use the --bind-to-core flag) >> >> 2. Process begins execution on core A >> >> 3. I enforce: "Bind to core B". (we must remember, it is only at runtime >> that I know what core I want to be bound to and not while launching the >> processes using mpirun). So my process shifts over to core B >> >> 4. MPI_Init() once again honors rankfile mapping(if any, default policy, >> otherwise ) and rebinds my process to core A >> >> 5. process finished execution and calls MPI_Finalize(), all the time on >> core A >> >> 6. mpirun exits >> -------------------------------------------- >> >> So if I place step-3 above after step-4, my request will hold for the >> rest of the execution. Please do let me know, if my understanding is >> correct. >> >> Thanks for all the help >> >> Sincerely, >> Siddhartha Jana >> HPCTools >> >> >> >> >> >> >> >> >> On 18 August 2013 10:49, Ralph Castain <r...@open-mpi.org> wrote: >> >>> If you require that a specific rank go to a specific core, then use the >>> rankfile mapper - you can see explanations on the syntax in "man mpirun" >>> >>> If you just want mpirun to respect an external cpuset limitation, it >>> already does so when binding - it will bind within the external limitation >>> >>> >>> On Aug 18, 2013, at 6:09 AM, Siddhartha Jana <siddharthajan...@gmail.com> >>> wrote: >>> >>> So my question really boils down to: >>> How does one ensure that mpirun launches the processes on the "specific" >>> cores that are expected of them to be bound to. >>> As I mentioned, if there were a way to specify the cores through the >>> hostfile, this problem should be solved. >>> >>> Thanks for all the quick replies, >>> -- Sid >>> >>> On 18 August 2013 09:04, Siddhartha Jana <siddharthajan...@gmail.com>wrote: >>> >>>> Thanks John. But I have an incredibly small system. 2 nodes - 16 cores >>>> each. >>>> 2-4 MPI processes. :-) >>>> >>>> On 18 August 2013 09:03, John Hearns <hear...@googlemail.com> wrote: >>>> >>>>> You really should install a job scheduler. >>>>> There are free versions. >>>>> >>>>> I'm not sure about cpuset support in Gridengine. Anyone? >>>>> >>>>> _______________________________________________ >>>>> users mailing list >>>>> us...@open-mpi.org >>>>> http://www.open-mpi.org/mailman/listinfo.cgi/users >>>>> >>>> >>>> >>> _______________________________________________ >>> users mailing list >>> us...@open-mpi.org >>> http://www.open-mpi.org/mailman/listinfo.cgi/users >>> >>> >>> >>> _______________________________________________ >>> users mailing list >>> us...@open-mpi.org >>> http://www.open-mpi.org/mailman/listinfo.cgi/users >>> >> >> _______________________________________________ >> users mailing list >> us...@open-mpi.org >> http://www.open-mpi.org/mailman/listinfo.cgi/users >> >> >> >> _______________________________________________ >> users mailing list >> us...@open-mpi.org >> http://www.open-mpi.org/mailman/listinfo.cgi/users >> > > _______________________________________________ > users mailing list > us...@open-mpi.org > http://www.open-mpi.org/mailman/listinfo.cgi/users > > > > _______________________________________________ > users mailing list > us...@open-mpi.org > http://www.open-mpi.org/mailman/listinfo.cgi/users >
