NR_CPUS & Timer Freq. Problem

[ma-fra]

Hi,

I wish I could have any explainations about a strange (to me) behavior when setting these kernel parameters.

My .config created by genkernel sets 4 cpus with 100Hz timer freq. and this was ok except for a midi sequencer (rosegarden)
who was complainig about this 100Hz setting. So, I tried to move it to 1000Hz and, at the same time, I decided to reduce the
CPU nr. to 2 (I have ONE Pentium4).

For some time I damned myself trying to understand why in this configuration during startup sequence udevd was not able to
communicate with my sata hardware (after sume time it gave up and I had my SATA disk missing - Linux is on hda and everything else was ok).

I thought it was because of other kernel setting changes, scsi or sata driver missing and so on, but, after weeks of kernel recompilations
I discovered the ONLY responsable parameters are the first two ones I reported above.

The situation is this:

with 4 cpu's everything works with any frequency (100 to 1000Hz).
with 2 or 3 cpu's with some frequency set I have just problems with udevd and SATA, with others I'm not even able to boot the system
because it starts to dump CPU1 registry and loop indefinitely (until i press RESET)

Any reason for this?

[jhohwie]

if you want to check how many cpus linux recognizes do:

[ma-fra]

I have one Pentium4 and system reports 2 cpu working (I can see them with top command) but I cannot reduce NR_CPUS parameter in .config from 4 to neither 3 nor 2 (without changing anything else but Timer frequency).


I recompiled with all the possible combinations: 2 cpu 100hz, 2 cpu 250hz, 2 cpu 350hz, 2 cpu 1000hz, 3 cpu 100 hz .....

some of these configurations boot without sata disk, others crash during booting sequence

that's the strange to me, I'm not changing anything else (sata driver, ACPI and so on) 4 cpu work, less no!