This is a paper from back in 2004, and some of the details have definitely
changed since then, but the high-level concepts are likely still to be a good
overview of how Open MPI's coll selection process works:
http://www.open-mpi.org/papers/ics-2004/
> On Oct 6, 2015, at 9:06 PM, Gilles G
Dahai Guo,
On 10/7/2015 3:08 AM, Dahai Guo wrote:
Thanks, Jeff. It is very helpful. some more questions :-):
1. There are many coll components, such as basic, tuned, self, cuda,
sm, and etc. Are they all selected at the MPI_Init time? or it just
select those satisfying some criteria,
Thanks, Jeff. It is very helpful. some more questions :-):
1. There are many coll components, such as basic, tuned, self, cuda, sm, and
etc. Are they all selected at the MPI_Init time? or it just select those
satisfying some criteria, hardware, communicator size? or only some specific
ones a
On Oct 6, 2015, at 10:19 AM, Dahai Guo wrote:
>
> Thanks, Gilles. Some more questions:
>
> 1. how does Open MPI define the priorities of the different collective
> components? what criteria is based on?
The priorities are in the range of [0, 100] (100=highest). The priorities tend
to be fai
On Oct 3, 2015, at 10:12 PM, Dahai Guo wrote:
>
> Thanks, Jeff. I am trying to understand in detail how Open MPI works in the
> run time. What main functions does it call to select and initialize the coll
> components?
In general, each framework (e.g., coll, pml, ...etc.) is polled during
MPI
Thanks, Gilles. Some more questions:
1. how does Open MPI define the priorities of the different collective
components? what criteria is based on?
2. how does a MPI collective function (MPI_Barrier for example) choose the
exact algorithm it use? based on message size, and communicator size? any
at first, you can check the priorities of the various coll modules
with ompi_info
$ ompi_info --all | grep \"coll_ | grep priority
MCA coll: parameter "coll_basic_priority" (current
value: "10", data source: default, level: 9 dev/all, type: int)
MCA coll: parameter
Thanks, Jeff. I am trying to understand in detail how Open MPI works in the run
time. What main functions does it call to select and initialize the coll
components? Using the "helloworld" as an example, how does it select and
initialize the MPI_Barrier algorithm? which C functions are involved
On Oct 2, 2015, at 2:21 PM, Dahai Guo wrote:
>
> Is there any way to trace open mpi internal function calls in a MPI user
> program?
Unfortunately, not easily -- other than using a debugger, for example.
> If so, can any one explain it with an example? such as helloworld? I build
> open MPI
Hi,
Is there any way to trace open mpi internal function calls in a MPI user
program? If so, can any one explain it with an example? such as helloworld? I
build open MPI with the VampirTrace options, and compile the following program
with picc-vt,. but I didn't get any tracing info.
Thanks
D.
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