Performance Issues on ccNuma-System

[Christoph Statz]

Hello Matt and PETSc-users,


>
> 1) With any performance question, please send the output of - 
> log_summary

You'll find the output attached
(But there is _really_ not much to see).

>
> 2) I think it is unlikely that cache misses are responsible for this
> performance. It is
>    much more likely that bandwidth limitations are responsible.

As far as I can see, there are neither bandwidth limitations nor  
latency problems (since there is an infiniband-interconnect).
MPI-Performance (Vampirtrace + Scalasca) looks good (late senders/ 
receivers, barriers etcpp.).
PAPI-Instrumentation says: cache misses.

>
> Please see the paper
>    by Kaushik and Gropp which models sparse matvec performance (on
> Dinesh's website).
>

Which Paper on which website. Please send a link.



> 3) You would see better performance using a block method. Sparse  
> matvec without
>    blocks will never see good percentages of peak (ditto for  
> backsolve).


How do I use the block methods?
Since I rely on the "user-level" interfaces kspsolve etcpp., I don't  
see how i could influence this.
You'll find basic source code attached.

Sincerly,
	Christoph


--
Christoph Statz

Institut für Nachrichtentechnik
Technische Universität Dresden
01062 Dresden

Email:  christoph.statz at mailbox.tu-dresden.de
Phone: +49 351 463 32287





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