SMP/HTT and Beowulf cluster on FreeBSD 7.0-RELEASE

[Michael Stogsdill]

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!

--
Michael B. Stogsdill
Sycamore.US Inc
Software Engineer/Security Administrator

[Kris Kennaway]

Post by Michael Stogsdill
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!

The answer is always "HTT performance depends on your workload. Try it
and see if it helps".

Kris

[Julian Elischer]

Post by Kris Kennaway

Post by Michael Stogsdill
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!

The answer is always "HTT performance depends on your workload. Try it
and see if it helps".

new processors are not quite as bad as the original HTT processors.
also, if the workload includes a mix of FP and integer work it will be
worth having them on.

Post by Kris Kennaway
Kris
_______________________________________________
http://lists.freebsd.org/mailman/listinfo/freebsd-smp

[Stephen Montgomery-Smith]

Post by Michael Stogsdill
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.)

[Petri Helenius]

Post by Stephen Montgomery-Smith
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).

In my experience HTT helps 20-30% in a well engineered workload. Extreme
care needs to be taken on minimizing synchronization primitive overhead
or that will take away your gain. (don't have 4 or 8 threads hammering
on one mutex a million times a second)

Pete