Re: Hyperthreading on 2.4.18 and 2.4.20 (Redhat)

From: red floyd (no.spam_at_here.dude)
Date: 03/18/04

Date: Thu, 18 Mar 2004 03:37:53 GMT

General Schvantzkoph wrote:

> On Wed, 17 Mar 2004 22:56:25 +0000, red floyd wrote:
>>I have an RH8 box, with 2 P4 Xeons. I recently enabled hyperthreading
>>in the BIOS, but am still only seeing 2 CPUs.
>>I have tried Redhat kernels 2.4.18-14 and 2.4.20-28.8. I looked at the
>>source in arch/i386/kernel/{setup,smpboot}.c, and it looks like there's
>>an error in the hyperthreading detection logic. There's some major
>>changes to this code in the vanilla 2.4.25 kernel.
>>Anyone got HT working on an SMP box with a stock RH kernel?
>>Alternatively, what's the diff between a RH kernel and a vanilla kernel?
>>If I put a vanilla kernel on this box, will it break any RH specific stuff?
>>Thanks in advance
> A standard kernel will work fine, go ahead and build a 2.4.25 and give it
> a try. BTW hyperthreading doesn't work very well, my tests showed that
> hyperthreading increades throughput by only 10% while reducing individual
> thread performance by 25%.

Is that in comparison to the UP kernel? I'm already running an SMP kernel,
since I have a dual CPU box.