[CentOS] Intel Xeon and hyperthreading

Wed Jun 7 17:13:57 UTC 2006
Sam Drinkard <sam at wa4phy.net>

Another question some of you may help me make decisions on.  I've been 
doing some reading that indicates that having HT turned on in this dual 
xeon machine might actually slow down the computing process rather than 
speeding it up.  I rebooted this a.m., and turned HT off, just prior to 
my main application run.  One thing that might be of note, this 
application is using OMP for utilizing both cpu's,  and prior to turning 
off HT, I had been running the software using 2 cpu's of the 4 that the 
OS sees.  I'm waiting on a model run to finish to see if there is any 
appreciable difference, but the one thing I do notice right off is cpu 
utilization is running close to 100% on both, where before, it averaged 
maybe 50% or thereabouts.  Again, sar is showing at last count, 83.56% 
utilization for user, 10.27% system and only 0.02% nice.  Idle was 5.74%.

I'm attempting to squeeze every last bit of processing power out of this 
machine, and would entertain suggestions on tuning if there happen to be 
any types of tuning that would help.

Sam

-- 
Sam W.Drinkard -- sam at wa4phy.net
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