topic Re: Tuning Kernel in Operating System - HP-UX

Tuning Kernel

jhuihuihi — Tue, 20 Jan 2004 02:54:37 GMT

Dear all,

I have workstation B2600, currently the percentage idle of CPU is 0.
Does anybody knows what kernel parameter should i change to improve performance ?
and also the values of that kernel.

thanks for your help

Best regards,

Jhui.

Re: Tuning Kernel

Elmar P. Kolkman — Tue, 20 Jan 2004 03:02:05 GMT

Kill ... ;-)

But I would start by looking what processes use and what processes need CPU time. Apparently the processes are using all CPU time available, so you need to free up those resources. There aren't any kernel parameters that can do this.

Re: Tuning Kernel

T G Manikandan — Tue, 20 Jan 2004 03:05:20 GMT

you are running with a single processor and the idle percentage is 0.

If you had checked with sar -u
But you can check the wio% and sys%.
If the wio% is high check whether the processor wait period is dependent on the memory usage and I/O.Also check the sys%.There might be swapping and the processes consume more CPU.
i.e.system processes are using the CPU or which is causing the wio% period.

If your usr% is occupying the entire CPU definitely you have to add CPUs

Re: Tuning Kernel

Ralph Haefner — Tue, 20 Jan 2004 12:00:24 GMT

It would probably be a good idea to set up sar to log results for a while if you're not doing that already. That way you could watch to see if it is always at 100%, or just certain times of day it is busy but others it is ok. You'll also be able to know if it is mosly user or I/O wait causing the CPU to be busy.

If there are certain jobs which cause large system loads, maybe you can shift when they are running to hours when the system is less busy. If it is constantly busy, and it is due to user processes instead of I/O wait, then you don't have many options other than adding CPU or forcing the users to run less processes.

Re: Tuning Kernel

Sridhar Bhaskarla — Tue, 20 Jan 2004 12:04:51 GMT

HI Jhui,

Only kernel parameter that may affect the CPU is the 'timeslice' parameter. The default of 10 is good. There was a patch that was resetting it to 1. So, make sure it is set to 10.

kmtune -l -q timeslice.

Can you post your ' sar 2 20' output for a better determination?.

-Sri

Re: Tuning Kernel

Bill Hassell — Tue, 20 Jan 2004 15:53:46 GMT

The way to improve this is to stop running all the processes that are consuming your CPU time. The top program will sort these out for you. Of course, you could have badly written programs that are wasting time so fixing these may help too.