downgrading multiprocessor to single cpu
 

Hi all,

just wondering, ive got a mates multiprocessor system that has just failed (dual slot 1 500's) and I was wondering if it would be ok to install a single processor motherboard p4 with a decent cpu (3.4 or similar). I dont know exactly what linux flavour he was using although I assume it would be RH or suse. Would switching from a multiprocessor system to a single processor system cause any issues, (kernal issues etc!?).

Taken from the kernel help text on SMP:
-----<snip>------------------------------------------------------------
If you [disable SMP], the kernel will run on single and multiprocessor machines, but will use only one CPU of a multiprocessor machine.
If you [enable SMP], the kernel will run on many, but not all, single machines. On a singleprocessor machine, the kernel
will run faster if you [disable SMP].
-----<snap>------------------------------------------------------------

So it is probably, but not fully, safe to simply try out, but not the most efficient way.

Note that if you use a modern Hyperthreading CPU on the new board, you will also need a SMP kernel to make use of it. As far as Linux is concerned (on the level of kernel configuration), multiprocessor and hyperthreading are the same.

If you don't have a hyperthreading CPU, I suggest you install a non-SMP kernel while using the old motherboard, then change boards.

Regards
ric.

No the kernel should not have any problems. When running a single processor system, you will notice a little hesitation switching from one program to the next that you did not notice from using a multiprocessor system. Though in some cases you will want to re-compile the kernel without SMP for a single processor system if you care for more performance (better program scheduling).

I suggest AMD processors because they are cheaper and faster than Intel processors.