Multiprocessor alternance
 

Hihoo! I'm very surprised, as i've compiled kernels for a P4 hyperthreading and for a true P2 multiprocessor, and, watching peacefully gkrellm monitor, i've seen that cpu's were working in alternance. Ex.: one at 80% and he other at 20%, or one at 99% and the other at 1%, and never both at 100%. So, as i can't sleep and eat since i've seen that, my only hope to understand this is you. Please, help me.

hyperthreading
 

Hello


My experiance with the 2.4 series kernels is that cpu's don't share work loads evenly between them. I have heard that the 2.6 series kernels do share the load better.

On a dual hyperthreaded xeon system, I have only seen maximum use of all cpu's when running 4 seti@home processes at the same time. For routine daily activities like compiling kernels :) there is always a cpu or two that make nothing but heat.

Thank you. Any other experiences?

My (hyperthreaded) dual xeon box shows the same alternation.

When using 3 of the 4 available cpu's (seti@home), 3 out of the 4 cpu's are at 99-100% (most of the time). But, never the same 3 cpu's.

Example, running only seti@home:

Cpu0 : 0.0% user, 0.0% system, 100.0% nice, 0.0% idle
Cpu1 : 0.0% user, 0.0% system, 0.0% nice, 100.0% idle
Cpu2 : 0.0% user, 0.7% system, 99.3% nice, 0.0% idle
Cpu3 : 0.0% user, 0.7% system, 99.3% nice, 0.0% idle

And a few cycles later:

Cpu0 : 0.0% user, 0.0% system, 0.0% nice, 100.0% idle
Cpu1 : 0.0% user, 0.7% system, 99.3% nice, 0.0% idle
Cpu2 : 0.0% user, 0.3% system, 99.7% nice, 0.0% idle
Cpu3 : 0.0% user, 0.8% system, 99.2% nice, 0.0% idle

I did experiment with disabeling hyperthreading (2 'real' cpu's instead of 4 'virtual'). The overall performance is better with 4 cpu's (although not that much).

Did not try the 2.6 kernel yet, so cannot tell anything about that.

Thanks again.

yes 2.4 kernels suck big time at multiprocessor balancing

definitely use the latest 2.6 as all modern distros now are 2.6 ready