Re: Intel-Hyperthread-Linux-Oracle
- From: Paul Drake <bdbafh@xxxxxxxxx>
- To: hkchital@xxxxxxxxxxxxxx
- Date: Wed, 8 Dec 2004 12:21:15 -0500
Hermant,
> How does Oracle on Linux treat Intel CPUs with HyperThreading ?
If you have a busy system that is not bound on physical IO, Oracle
treats them badly :).
Its a matter of how the operating system treats them.
I'll assume for a minute that you are talking about RHEL 3.0 ES Update
2- but this could be for any Linux.
During boot, the OS maps the run queue of the logical CPU to the physical CPU.
In this manner, if the number of processes that are running is less
than or equal to the number of physical CPUs, then the logical CPUs
are not used.
As additional processes are scheduled to run, a subset will run on the
logical (hyperthreaded) processor(s).
I am not aware of processor-affinity code in the 2.4 kernels but had
heard mentioning of this in the 2.6 series.
run top - and see for yourself.
Paul
On Thu, 09 Dec 2004 00:33:27 +0800, Hemant K Chitale
<hkchital@xxxxxxxxxxxxxx> wrote:
>
> How does Oracle on Linux treat Intel CPUs with HyperThreading ?
>
> Also, does the software license have to be for twice the number of CPUs .
>
> I believe that, on a 4-CPU machine, Oracle actually sets CPU_COUNT to 8
> on HT architecture.
>
> Hemant K Chitale
> http://web.singnet.com.sg/~hkchital
>
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>
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