And there's a typo in my first paragraph. The flag currently defaults to
1 (print the warning). It should be switched to 0 to turn off the
warning. Sorry for any confusion I might have caused -- I blame the lack
of caffeine in the morning.
Brian
On Wed, 21 May 2008, Pavel Shamis (Pasha) wrote:
I'm agree with Brian. We may add to the warning message detailed
description how to disable it.
Pasha
Brian W. Barrett wrote:
I think having a parameter to turn off the warning is a great idea. So
great in fact, that it already exists in the trunk and v1.2 :)! Setting
the default value for the btl_base_warn_component_unused flag from 0 to 1
will have the desired effect.
I'm not sure I agree with setting the default to 0, however. The warning
has proven extremely useful for diagnosing that IB (or less often GM or
MX) isn't properly configured on a compute node due to some random error.
It's trivially easy for any packaging group to have the line
btl_base_warn_component_unused = 0
added to $prefix/etc/openmpi-mca-params.conf during the install phase of
the package build (indeed, our simple build scripts at LANL used to do
this on a regular bases due to our need to tweek the OOB to keep IPoIB
happier at scale).
I think keeping the Debian guys happy is a good thing. Giving them an
easy way to turn off silly warnings is a good thing. Removing a known
useful warning to help them doesn't seem like a good thing.
Brian
On Wed, 21 May 2008, Jeff Squyres wrote:
What: Change default in openib BTL to not complain if no OpenFabrics
devices are found
Why: Many linuxes are shipping libibverbs these days, but most users
still don't have OpenFabrics hardware
Where: btl_openib_component.c
When: For v1.3
Timeout: Teleconf, 27 May 2008
Short version
=============
Many major linuxes are shipping libibverbs by default these days.
OMPI will therefore build the openib BTL by default, but then
complains at run time when there's no OpenFabrics hardware.
We should change the default in v1.3 to not complain if there is no
OpenFabrics devices found (perhaps have an MCA param to enable the
warning if desired).
Longer version
==============
I just got a request from the Debian Open MPI package maintainers to
include the following in the default openmpi-mca-params.conf for the
OMPI v1.2 package:
# Disable the use of InfiniBand
# btl = ^openib
Having this in the openmpi-mca-params.conf gives Debian an easy
documentation path for users to shut up these warnings when they build
on machines with libibverbs present but no OpenFabrics hardware.
I think that this is fine for the v1.2 series (and will file a CMR for
it). But for v1.3, I think we should change the default.
The vast majority of users will not have OpenFabrics devices, and we
should therefore not complain if we can't find any at run-time. We
can/should still complain if we find OpenFabrics devices but no active
ports (i.e., don't change this behavior).
But for optimizing the common case: I think we should (by default) not
print a warning if no OpenFabrics devices are found. We can also
[easily] have an MCA parameter that *will* display a warning if no
OpenFabrics devices are found.
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