Re: Shared Memory usage in -machinefile

Patrick,

thx, I have guest account to a cluster with Myrinet and was wondering as =
not=20
seeing anything with ipcs. Yes, I agree that IPC could be better implemen=
ted to=20
be proper removed after a job. Somewhere I found some experimental code o=
nce to=20
attach meta-information to this IPC stuff, to get it removed later.

Cheers - Reuti


Quoting Patrick Geoffray <[email protected]>:

> Hi Reuti,
>=20
> Reuti wrote:
> > Question is: how is Myrinet behaving in this case? Different from the
> default=20
> > MPICH, or could the above statement give under some circumstances a l=
ess=20
> > optimal result?
>=20
> node1:2
>=20
> will be expanded in
>=20
> node1
> node1
>=20
> The shared memory support in MPICH-GM is very different from the=20
> -comm=3Dshared of MPICH-P4. When shared memory is enabled (the default)=
=20
> all processes from the same MPI job running on the same host (hostname=20
> is the same) will use shared memory. We don't use IPC for allocated=20
> shared memory segments (IPC is a mess), so shared memory is either used=
=20
> or not used, there is no other variation.
>=20
> So, you can use ":n" or list the same node n times, there would be no=20
> difference regarding shared memory.
>=20
> Patrick
> --
>=20
> Patrick Geoffray
> Myricom, Inc.
> http://www.myri.com
>=20