On 04/26/2013 08:53 PM, Ralph Castain wrote:
On Apr 26, 2013, at 7:40 PM, Orion Poplawski <or...@cora.nwra.com> wrote:
On 04/25/2013 04:48 AM, Jeff Squyres (jsquyres) wrote:
Orion --
I would just caution against using Open MPI with a thread-enabled libevent. In
most cases, the performance impact wouldn't matter, but the whole point of MPI
is to be high performance. The current 1.7 series does *not* use a
thread-enabled libevent because it detracts from performance. Hence, using a
thread-enabled libevent detracts from Open MPI's main purpose.
If Open MPI is suddenly bundled with a thread-enabled libevent, *performance will go down* and
users will be unhappy. We have learned painfully over the years that users expect good performance
out of the box -- if they have get "bad" performance out of the box and have to do
something special to enable "good" performance, they'll be annoyed and blame Open MPI.
So I would request that you do *not* link Open MPI against a thread-enabled
libevent until we are able integrate such functionality properly, and take
measures to mitigate the performance implications (which likely won't be until
at least the 1.9 series).
So, the Fedora Packaging committee has taken that part to heart, but not the
bundling:
* Bundling exception for libevent in openmpi -
https://fedorahosted.org/fpc/ticket/273 (spot, 16:16:52)
* ACTION: FPC is pretty universally against this bundling, spot will
try to make a libevent-nothread.so and update libevent. (spot,
16:26:38)
Just for clarification: who or what is "spot"?
Tom "spot" Callaway - one the packaging committee members
So it looks like I will need to shortly be looking at how to link against an
external libevent. Any help with that would be greatly appreciated.
As I said, I'll take a look at it, but can't commit to having it available any
time soon. It isn't something I would suggest someone try who isn't fully
versed in OMPI's code base.
Yeah, I'm not looking forward to it. I get to at least wait until the
non-threaded version of libevent is available.
--
Orion Poplawski
Technical Manager 303-415-9701 x222
NWRA/CoRA Division FAX: 303-415-9702
3380 Mitchell Lane or...@cora.nwra.com
Boulder, CO 80301 http://www.cora.nwra.com
