Performance Issues on ccNuma-System

Matthew Knepley knepley at
Tue Oct 14 08:10:42 CDT 2008

On Tue, Oct 14, 2008 at 2:06 AM, Christoph Statz
<christoph.statz at> wrote:
>   The sparse matrix is MUCH to big for the cache so has to stream through
> from memory,
> thus the huge number of "cache misses". This same performance issue occurs
> on
> all modern systems.
> Yes, of course. But on most modern systems i don't have the "problem" that
> the cache is held coherent which causes a bunch of extra cycles penalty.
> I don't have performance problems on our Clusters. It is just the "big"
> machine.

Write down the balance between cycles and memory bandwidth for these machines.
I am guessing the clusters have better balance since they tend to have
slower processors.


> Christoph
> --
> Christoph Statz
> Institut für Nachrichtentechnik
> Technische Universität Dresden
> 01062 Dresden
> Email:  christoph.statz at
> Phone: +49 351 463 32287

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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