[lug] RedHat Hat & Multi CPU's

[Richard Fifarek]

	There is some debate on the kernel mailing list on that.  
Anecdotally, we have seen that if there are 3-4 processes running that
will each fully load one CPU, then you are going to take a performance hit
per process.  I suspect it's because the scheduler treats it as if there 
are physically 4 CPUs instead of 2.

On Wed, 6 Nov 2002 neelsmith74 at netscape.net wrote:

> Thanks Richard.
> 
> My next question is does this effect the system if this is left on; since I do not have any multithreaded programs running.
> Is there a performace hit if im not using it-it does not look like it.
> Thanks again,
> Nate.
> 
> 
> Richard Fifarek <rfifarek at silug.org> wrote:
> 
> >
> >    It means that hyperthreading is enabled.  Typically you can 
> >disable it in the BIOS, but if not, pass noht (if I recall) to the kernel 
> >as a boot option.
> >
> >On Wed, 6 Nov 2002 neelsmith74 at netscape.net wrote:
> >
> >> Hi,
> >> I just upgraded a dual Z 2ghz from RH7.3-SMP to RH8.0-SMP
> >> It now looks as if RH8.0 thinks I have 4 CPU's????
> >> 
> >> When I take #top
> >> CPU0 states ..
> >> CPU1 states ..
> >> CPU2 states ..
> >> CPU3 states ..
> >> ::and::
> >> migration_CPU0
> >> migration_CPU1
> >> migration_CPU2
> >> migration_CPU3
> >> ::and::
> >> ksoftirqd_CPU0
> >> ksoftirqd_CPU1
> >> ksoftirqd_CPU2
> >> ksoftirqd_CPU3
> >> I image this is some kind of system d that is running, but why is my question and how did it come up with 4 CPU's instead of 2CPU's?
> >> 
> >> Thanks,
> >> Nate - the other one
> >> 
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> >
> >         -----------------------------------------------------
> >         Richard H. Fifarek             rfifarek at silug.org
> >             -----------------------------------------------------
> >
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	     -----------------------------------------------------
	     Richard H. Fifarek	       		rfifarek at silug.org
             -----------------------------------------------------