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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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