Saliya,
btl is a point to point thing only.
collectives are implemented by the coll mca
the sm coll mca is optimized for shared memory, but support intra node
communicators only.
the ml and hierarch coll have some optimizations for intra node
communications.
as far as i know, none of these are used in production.
Cheers,
Gilles
On 9/1/2015 1:57 PM, Saliya Ekanayake wrote:
One more question. I found this blog from Jeff [1] on vader and I got
the impression that it's used only for peer-to-peer communications and
not for collectives. Is this true or did I misunderstand?
[1]
http://blogs.cisco.com/performance/the-vader-shared-memory-transport-in-open-mpi-now-featuring-3-flavors-of-zero-copy
On Tue, Sep 1, 2015 at 12:40 AM, Gilles Gouaillardet
<gil...@rist.or.jp <mailto:gil...@rist.or.jp>> wrote:
you can try
mpirun --mca btl_base_verbose 100 ...
or you can simply blacklist the btl you do *not* want to use, for
example
mpirun --mca btl ^sm
if you want to use vader
you can run
ompi_info --all | grep vader
to check the btl parameters,
of course, reading the source code is the best way to understand
what the vader btl can do and how
Cheers,
Gilles
On 9/1/2015 1:28 PM, Saliya Ekanayake wrote:
Thank you Gilles. Is there some documentation on vader btl and
how I can check which (sm or vader) is being used?
On Tue, Sep 1, 2015 at 12:18 AM, Gilles Gouaillardet
<gil...@rist.or.jp <mailto:gil...@rist.or.jp>> wrote:
Saliya,
OpenMPI uses btl for point to point communication, and
automatically selects the best one per pair.
Typically, the openib or tcp btl is used for inter node
communication, and the sm or vader btl for
intra node.
note the vader btl uses the knem kernel module when available
for even more optimized configurations.
Cheers,
Gilles
On 9/1/2015 5:59 AM, Saliya Ekanayake wrote:
Hi,
Just trying to see if there are any optimizations (or
options) in OpenMPI to improve communication between intra
node processes. For example do they use something like
shared memory?
Thank you,
Saliya
--
Saliya Ekanayake
Ph.D. Candidate | Research Assistant
School of Informatics and Computing | Digital Science Center
Indiana University, Bloomington
Cell 812-391-4914 <tel:812-391-4914>
http://saliya.org
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Saliya Ekanayake
Ph.D. Candidate | Research Assistant
School of Informatics and Computing | Digital Science Center
Indiana University, Bloomington
Cell 812-391-4914 <tel:812-391-4914>
http://saliya.org
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--
Saliya Ekanayake
Ph.D. Candidate | Research Assistant
School of Informatics and Computing | Digital Science Center
Indiana University, Bloomington
Cell 812-391-4914
http://saliya.org
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