Re: [Ganglia-developers] Hyperthreading patch for cpu_num on Linux

[Rick M. <rf...@os...>]

On Wed, 23 Jul 2003, Brooks Davis wrote:

> I don't think you need to worry about this too much since all MP capable
> cpus with the HT flag set are Xeons which actually support two siblings.
> I would point out that if you go to all the trouble of removing the
> logical CPUs from the output, someone is probalby going to get annoyed
> that you did that because they wanted to see them in the output.  After
> all, for some applictions, treating each logical CPU as a physical CPU
> is a good fit.

Unfortunately, this doesn't appear to hold true either.  I have found
three dual XEON systems around here and checked cpuinfo in each:

System #1 (No ht): 2 procs shown, ht flag set, no physical id or siblings
fields.
Sysyem #2 (ht): 4 procs shown, ht flag set, no physical id or siblings
fields.
System #3 (ht); 4 procs shown, ht flag set, physical ids of 0,0,3,3 and
siblings=2 for all.

So we can't count on having the physical id or the siblings field
present. I am inclined to go with the config file option until there
becomes a more standard way of extracting this info.

--Rick