CPU Hyperthreading ON or OFF?

[dkosheba1]

I have been running my 8 cpu 64-bit XP box for years with Hyperthreading on.   Recently I heard this does not necessarily help at all with regards to Moldflow solvers. 

1.  Does anybody have experience with this turned on and off for comparison of solve times?

2.  If off, will this effect multitasking on the same box analysis is running on.  i.e. surfing, checking e-mail while processing

3.  Does it effect each solver differently, like cooling, flow, warp, etc....?

Thanks for the feed back, Don

[dkosheba1]

O.K.   I will reply to my own thread,  I don't have a comparison with traditional cool, flow, warp.  But with Hyperthreading turned off, there is a small improvement.

Before:

Execution time, Cool(FEM) solver

Analysis commenced at Thu Sep 16 14:27:33 2010

Analysis completed at Thu Sep 16 14:47:7 2010

CPU time used 5839.00 s

Elapsed wall clock time 1174.00 s

After:

Execution time, Cool(FEM) solver

Analysis commenced at Thu Sep 16 15:15:48 2010

Analysis completed at Thu Sep 16 15:32:30 2010

CPU time used 2498.00 s

Elapsed wall clock time 1002.00 s

[phil-mcam]

I cannot believe this subject has so little traction.

This came up from a customer of mine who got new "junk" machines. He turned off HT and the machines are running much faster. 

I was wondering how it's been working for you.

[tim.vanast]

Yes, hyperthreading OFF is the way to go.  It will at worst, be slightly better, and at best, much better for your simulation solve times.  An old college of mine, Jameson Fee, used to run benchmarks with a variety of settings.  And hyperthreading was always slower.  But it was really cool to look at the task manager with 24 processors showing (for a dual 6 core machine).

Tim