That's pretty weird, but you're right. Here is the code that do
exactly what you state.
} else if(strcmp(ompi_mtl_base_selected_component-
>mtl_version.mca_component_name, "psm") != 0) {
/* if mtl is not PSM then back down priority, and require the
user to */
/* specify pml cm directly if that is what they want
priority */
/* of 1 is sufficient in that case as it is the only pml
that */
/* will be considered */
*priority = 1;
}
george.
On Jan 13, 2009, at 20:31 , Brian Barrett wrote:
George -
I don't care what we end up doing, but what you state is wrong. We
do not use the CM for all other MTLs by default. PSM is the *ONLY*
MTL that will cause CM to be used by default. Portals still falls
back to OB1 by default. Again, don't care, don't want to change,
just want the documentation and current behavior to match.
Brian
On Jan 13, 2009, at 6:27 PM, George Bosilca wrote:
This topic was raised on the mailing list quite a few times. There
is a major difference between the PSM and the MX support. For PSM
there is just an MTL, which makes everything a lot simpler. The
problem with MX is that we have an MTL and a BTL. In order to
figure out which one to use, we have to call the init function and
this function initialize MX. The MTL use the default values for
this, while the BTL give some hints to the MX library (about how to
behave based on the support level we want, i.e. such as who will
deal with shared memory or self communications). As there can be
only one MX initialization, as the MTL initialize first, the BTL
will always get a wrongly initialized MX library (which can
generate some performance problems).
What Brian describe is the best compromise we manage to find few
months ago. If you want to get the MX CM to run, you will have to
clearly specify on the command line --mca pml cm. All other MTL
will have the behavior described on the README.
george.
On Jan 13, 2009, at 20:18 , Brian Barrett wrote:
On Jan 13, 2009, at 5:48 PM, Patrick Geoffray wrote:
Jeff Squyres wrote:
Gaah! I specifically asked Patrick and George about this and
they said that the README text was fine. Grr...
When I looked at that time, I vaguely remember that _both_ PMLs
were initialized but CM was eventually used because it was the
last one. It looked broken, but it worked in the end (MTL was
used with CM PML). I don't know if that behavior changed since.
I just tested 1.3rc4 with MX and it uses the btl by default. The
reason is the cm init lowers the priority to 1 unless the MTL that
loaded is psm, in which case it stays at the higher default of
30. It's a fairly easy fix, I think. But the last time this was
discussed people in the group had objections to using the MTL by
default with MX.
Brian
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