Re: Oracle CPU_COUNT

I don't mean to be silly ... but are you having a performance problem ?

Oracle will use it's own code to auto-pick up the number of CPU's Win2K thinks it has.

so if you knock off the hyperthreading it and bounce it should pick up the change.

Without going into a fair amount of depth on Xeon instruction scheduling you will only be able to do relatively

simple 'before-after' testing .

But !

If you are (sorry about the verbiage) using a lot of PQ and/or changing around parallel_automatic_tuning and those types of variables then you run a (strong) chance of plan changes - so effectively it is a different machine to Oracle with different resources for optimization since for parallel queries CPU_COUNT is a factor in the optimization.

My 0.02c
"Carol" <carol.mcalear_at_pulsion.co.uk> wrote in message news:5fdaf21e.0210290302.7236cfa3_at_posting.google.com...
> Hi
>
> I have a Compaq DL580 server with 2 Xeon P1.7 processors; the server
> is set up with hyper threading. I have installed Win2K Advanced
> Server and Oracle 9.0.2 running a live database. When I open task
> manager it appears that I have 4 processors and they are all getting
> used. I checked oracles CPU_COUNT and it is set at 4. My question is
>
> Will I see a performance improvement if I turn off the hyper threading
> and change the CPU_COUNT to 2?
>
> I have read that it is not recommended to change the CPU_COUNT would I
> be better uninstalling and re-installing oracle and let it pick this
> up for itself or is there another option, I can afford to have the
> database down for a weekend?
>
> Thanks in advance
>
> Carol
Received on Tue Oct 29 2002 - 05:46:42 CST