[Beowulf] Re: RRDtools graphs of temp from IPMI

[Lombard, David N]

On Tue, Nov 11, 2008 at 06:51:46AM -0800, Dave Love wrote:
> Prentice Bisbal <prentice at ias.edu> writes:
> 
> > The advantage of using IPMI is that it is hardware based, so there
> > shouldn't be any OS noise to slow down the MPI calculations.
> 
> Yes iff you do it out-of-band, which is probably less convenient, and is
> significantly slower on our systems, at least.  Actually, is it clear
> that interacting with the firmware generally won't cause any jitter?  I
> could imagine it might.

IPMI lives on the BMC.  That's not to say there's zero interaction, but
the impact of OOB IPMI should really be very limited.

> Our vendor installed a daemon doing in-band IPMI sensor probes which I
> didn't initially know about, since it wasn't sending the ganglia metrics
> correctly anyhow.  I don't know whether that means they disagree with
> the effect on MPI performance or what.

It's a preference issue; there are reasonable arguments to be made in either
direction.

-- 
David N. Lombard, Intel, Irvine, CA
I do not speak for Intel Corporation; all comments are strictly my own.