enabling hyperthreading in PE 1750

Ramon Diaz-Uriarte rdiaz at cnio.es
Fri Oct 17 06:07:01 CDT 2003

Dear All,

We have two Poweredges 1750; each has 2 Xeon's (3.00 GHz) and 4 GB RAM; in the 
BIOS, hyperthreading is enabled. However, we are having a hard time getting 
hyperthreading to work: 

- When we use the prebuilt ISO for Debian 
(http://gustavo.imente.com/debian/bootbf2.4.21-ac4-4.iso) we only see two 
processors listed in /proc/cpuinfo.

- If we use the 2.4.22-1-686-smp kernel from Debian testing (sarge), we again 
only see two processors.

- However, if we boot using Cluster Knoppix (http://bofh.be/clusterknoppix/), 
v.3.2 (2003-06-06), we do see the 4 logical processors (though we only get 
900 MB RAM, which, we guess, woul just require setting CONFIG_HIGHMEM4G=y). 
[No, we can't install from ClusterKnoppix, because it does not see our SCSI 

But we've been comparing the config files for the different kernels and don't 
see where the difference is. We've also tried recompiling the kernel, and we 
still don't see the 4 CPUs.

What are we doing wrong? (We've searched all the list archives, and it seems 
that nobody else has had a similar problem; if anything, people wanted to 
turn off hypterthreading).



Ramón Díaz-Uriarte
Bioinformatics Unit
Centro Nacional de Investigaciones Oncológicas (CNIO)
(Spanish National Cancer Center)
Melchor Fernández Almagro, 3
28029 Madrid (Spain)
Fax: +-34-91-224-6972
Phone: +-34-91-224-6900

PGP KeyID: 0xE89B3462

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