RE: Intel-Hyperthread-Linux-Oracle

From: Jesse, Rich <Rich.Jesse_at_quadtechworld.com>
Date: Wed, 8 Dec 2004 12:29:14 -0600
Message-ID: <FBE1FCA40ECAD41180400050DA2BC54004E93FAC@qtiexch2.qgraph.com>

And this would depend on whether or not the kernel was built for SMP, = correct?

Rich

-----Original Message-----
Sent: Wednesday, December 08, 2004 11:21 AM To: hkchital_at_singnet.com.sg
Subject: Re: Intel-Hyperthread-Linux-Oracle

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

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Received on Wed Dec 08 2004 - 12:32:52 CST