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From: Sajjad Tabib (stabib_at_[hidden])
Date: 2007-10-25 12:08:23

Hi Brian,

I have actually created a new MTL, in which I have added heterogeneous
support. To experiment whether CM worked in this environment, I took out
the safeguards that prevented one to use CM in a heterogeneous
environment. Miraculously, things have been working so far. I haven't
examined data integrity to an extent that I could say everything works
perfectly, but with MPI_INTS, I do not have any endian problems. Now,
based on my initial tests, I have came to the understanding that the PML
CM safeguard against heterogeneous environments was a mechanism to prevent
users from using existing MTLs. But, if an MTL supports heterogeneous
communication, then it is possible to use the CM component. What is your
take on this?
Anyways, going back to the datatype usage. When you say that: "it's known
the datatype usage in the CM PML won't support heterogeneous operation"
could you please breifly explain this in more detail? I have been using
ompi_mtl_datatype_pack and ompi_mtl_datatype_unpack, which use
ompi_convertor_pack and ompi_convertor_unpack, for data packing. Do you
mean that these functions will not work correctly?

Thank You,

Sajjad Tabib

Brian Barrett <brbarret_at_[hidden]>
Sent by: devel-bounces_at_[hidden]
10/24/07 10:04 PM
Please respond to
Open MPI Developers <devel_at_[hidden]>

Open MPI Developers <devel_at_[hidden]>

Re: [OMPI devel] PML cm and heterogeneous support

No, it's because the CM PML was never designed to be used in a
heterogeneous environment :). While the MX BTL does support
heterogeneous operations (at one point, I believe I even had it
working), none of the MTLs have ever been tested in heterogeneous
environments and it's known the datatype usage in the CM PML won't
support heterogeneous operation.


On Oct 24, 2007, at 6:21 PM, Jeff Squyres wrote:

> George / Patrick / Rich / Christian --
> Any idea why that's there? Is that because portals, MX, and PSM all
> require homogeneous environments?
> On Oct 18, 2007, at 3:59 PM, Sajjad Tabib wrote:
>> Hi,
>> I am tried to run an MPI program in a heterogeneous environment
>> using the pml cm component. However, open mpi returned with an
>> error message indicating that PML add procs returned "Not
>> supported". I dived into the cm code to see what was wrong and I
>> came upon the code below, which basically shows that if the
>> processes are running on different architectures, then return "not
>> supported". Now, I'm wondering whether my interpretation is correct
>> or not. Is it true that the cm component does not support a
>> heterogeneous environment? If so, will the developers support this
>> in the future? How could I get around this while still using the cm
>> component? What will happen if I rebuilt openmpi without these
>> statements?
>> I would appreciate your help.
>> Code:
>> mca_pml_cm_add_procs(....){
>> 107 for (i = 0 ; i < nprocs ; ++i) {
>> 108 if (procs[i]->proc_arch != ompi_proc_local()-
>> >proc_arch) {
>> 110 }
>> 111 }
>> 112 #endif
>> .
>> .
>> .
>> }
>> Sajjad Tabib
>> _______________________________________________
>> devel mailing list
>> devel_at_[hidden]
> --
> Jeff Squyres
> Cisco Systems
> _______________________________________________
> devel mailing list
> devel_at_[hidden]

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