SMP/HTT and Beowulf cluster on FreeBSD 7.0-RELEASE

[Stephen Montgomery-Smith]

Michael Stogsdill wrote:
> Hey, I have a question that I can't seem to find a decent answer to. The mailing lists have had some similar topics, but they were mostly for the 6.x-RELEASE and other minor differences. 
> 
> Heres my situation; I'm trying to create a beowulf cluster running FreeBSD 7.0-RELEASE consisting of 8 systems all running on Dual Xeon w/HTT both running at 2.8Gz. What exactly this system will be doing I can't say, so lets just think about the performance of the cluster running a benchmarking tool similar to sysbench. Because they are dual processor systems, I will be using the SMP kernel already, so I'm wondering if turning on HTT will help or hinder my Beowulf' performance. The cluster is not yet operational, otherwise I would do some tests myself!
> 
> Thanks!

My personal experience is that HTT did help.  This was with an older 
Xeon dual processor system, and I was running multithreaded programs 
that were basically huge amounts of floating point calculations (a bit 
like FFT).

Also, recent advances in FreeBSD have made it extremely good at running 
multithreaded programs, but I still think it would be worthwhile trying 
Linux as well.  In the old days, Linux did much better, and who knows, 
they might have advanced ahead again.  Since you are looking to get 
overy ounce of performance out of your computers, I would try out all 
the possibilities and see what works best.

(And to answer your question, I found recent versions of FreeBSD 
slightly better than Linux at taking advantage of HTT in my particular 
applications.)