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Re: top output, hyper-threading, and 2.5.69 kernel

On Fri, May 16, 2003 at 05:09:54PM -0400, James D. Freels wrote:
> I have a dual-Xeon (hyperthread) processor system on an Intel serverboard.  
> When booted up under kernel 2.4.20, the top output indicates 4 processors are 
> running.  I can toggle the output using the "1" key to show all processors 
> combined, or 4 independent processors.
> When I boot up under the 2.5.69 kernel (there does not appear to be a HT 
> switch in the menuconfig, but I do have CONFIG_X86_HT=y in the .config file), 
> the top command only shows 2 processors running.  

Obvious: Do you have SMP enabled?

> Questions:
> Does this mean that hyperthreading is not enabled ?

What does 'dmesg' say?

> If hyperthreading is enabled, and I have two physical processors, should the 
> top command show 4 processors running ?

Yes.  As far as I know, anyway, I've never had the pleasure to play with
one of those beasts :)

> Why is the top output different between 2.4.20 and 2.5.69 ?

I don't know.  If you can't find an obvious answer (and no one else
seems to have come up with one in the past week), then you should
definitelty contact lkml about this.

Rob Weir <rweir@ertius.org>  |   mlspam@ertius.org   |   http://www.ertius.org/
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