Process binding on Dual P4 Xeon

[Simon Oliver <simon.oliver@umist.ac.uk>]

I have recently installed a new dual P4 Xeon system.

For a particularly computeintensive program I have been advised to turn of
hyperthreading in the BIOS, so now Linux sees two CPUs instead of four
logical CPUs - makes sense :-)

I know that the binding of a process to a cpu is "loose" under linux (as
apposed to Irix say) and one expects jobs to hop between CPUs every now
and then.

But I have been monitoring (via top) a simple perl script (no forks or
threading involved) and not only does it switch CPU, sometimes it seems to
split accross the CPUs with 50% utilization on each CPU, or even a 25/75
split.  I have never noticed this before on dual CPU machines (I have a
few dual PIIIs).

The machine is still running the SuSE supplied SMP kernel:

Linux version 2.4.18-64GB-SMP (root@SMP_X86.suse.de) (gcc version 2.95.3
20010315 (SuSE)) #1 SMP Wed Mar 27 13:58:12 UTC 2002

Please enlighten me.

-- 
  Simon Oliver