How does Linux number hyperthreaded processors?

I have a dual Zeon processor that Linux lists as 4 processors (there are two physical ones and each has two hyperthread units. I am assigning threads to individual processors and I want them on different physical processors. Are processor 0 and 1 on the same physical processor and 2 and 3 on the other processor or are 0 and 1 on two different physical processors and 3 and 4 their hyperthread pairs?

I am upgrading my system from a dual Pentium 3 where this was not an issue. If worse comes to worse I can disable hyperthreading, but I would like to clarify this if possible.

Thanks in advance,

Marco ________________________ Marc Reinig UCO/Lick Observatory Laboratory for Adaptive Optics

Reply to
Marc Reinig
Loading thread data ...

have you examined /proc/cpuinfo?

Reply to
AZ Nomad

There is a small script i wrote that, may help you, here:

formatting link

It only detects if the CPU can hyperthread atm, as I wrote it to check my servers, I cant reboot the servers to test the differences with HT on and off. If you use it and can see the differences. then feel free to update the script. I would appraciate any changes making their way back to my site.

If you have an intel machine that has ht and you post the /proc/ cpuinfo contents with it on and off then we maybe can tell you the differences..

The key lies in the combination of physical id and logical id iirc.

Reply to
Pvt Ryan

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.