topic Processor Utilization in Operating System - HP-UX

Processor Utilization

Madanagopalan S — Mon, 16 Oct 2000 06:38:51 GMT

N4000-Dual Processor.

We are facing processor 1 utlization is much heavy than Processor 0 always.
I have looked the statistics for one month and found that processor 1 is utilized
nearly 60% and processor 0 is utilized only 30%. How can I load balance the
processor? Is there any way? Pls help.

Re: Processor Utilization

Alex Glennie — Mon, 16 Oct 2000 06:58:26 GMT

see ITRC DOC ID KBRC00000947 : System Performance Tunning Guide may be helpful ?

It may also be a programming threads issue i guess depending upon your setup,load,applications etc ......

Re: Processor Utilization

Andy Monks — Mon, 16 Oct 2000 07:21:15 GMT

I'm not sure I'd worry about averages over a month, as it's too longer a period. However, during peak load, that is when I would be concerned. If 1 cpu is at 100% and the other is at 50% then that's something to worry about.

The scheduler will alway try not to move a process from 1 cpu to another as it's wasteful. However, if the cpu it would like to run it on is very busy then obviously it will. If both cpu's have a tiny run queue, the scheduler will probably decide to keep it where it is.

Typically, at peak, cpu 0 will always be slightly higher than the rest and this is normal.

Re: Processor Utilization

Emil Velez — Tue, 17 Oct 2000 18:43:45 GMT

When you look at a long time utilization this number will be skewed.

Every 1 second if there is a 20% deviation between the utilization of 1 processor and
another a single thread may be moved to balance utilization. Many times based on
the runable threads there is not one that can be moved. But the OS does try to
balance the CPU utilization. It is expensive to move threads between processors

From HP Education Customer Course: Inside HPUX

Re: Processor Utilization

Alan Riggs — Tue, 17 Oct 2000 19:12:36 GMT

To add to the words above: compare only at peak usage. Alternatively, look at a history with sar or measurewear/Perfview and check relative values at specific time.

60%/30% is not really indicative of a problem. Only when one processor approaches full load is balancing really a concern.