[petsc-users] Configuring PETSc for KNL

[Matthew Knepley]

On Wed, Apr 5, 2017 at 10:26 PM, Jed Brown <jed at jedbrown.org> wrote:

> Matthew Knepley <knepley at gmail.com> writes:
>
> > On Wed, Apr 5, 2017 at 12:23 PM, Justin Chang <jychang48 at gmail.com>
> wrote:
> >
> >> I simply ran these KNL simulations in flat mode with the following
> options:
> >>
> >> srun -n 64 -c 4 --cpu_bind=cores numactl -p 1 ./ex48 ....
> >>
> >> Basically I told it that MCDRAM usage in NUMA domain 1 is preferred. I
> >> followed the last example: http://www.nersc.gov/users/
> >> computational-systems/cori/configuration/knl-processor-modes/
> >>
> >
> > Right. I think, from the prior discussion, that -m 1 causes the run to
> fail
> > if you spill out of MCDRAM. I think that is usually
> > what we want since it makes things easier to interpret and running MKL
> from
> > DRAM is like towing your McLaren with
> > your Toyota.
>
> I'm not sure whether getting the Intel acronyms mixed up (KNL vs MKL)
> makes the quote above better or worse.
>

Too cryptic. Are you saying that this cannot be what is happening? How
would you explain
the drop off in performance?

  Matt

-- 
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener
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