topic cpu and process problem in Operating System - HP-UX

cpu and process problem

haiyu Huang — Fri, 26 Oct 2001 02:51:28 GMT

as we know, processes can be initialized on the selected CPU and will not be transferred without termination or mannual adjustment. here is a question: at a multi-processor server, when business is not busy, some processes are bundled on dedicated CPU, at that time, this cpu's workload is acceptable, but when business is very busy, this CPU's workload is at the top, how could system balance the utilization ratio within CPUs?

Re: cpu and process problem

JACQUET — Fri, 26 Oct 2001 05:46:50 GMT

Hi,

what could fullfill your need is to use PRM (processus ressources managment), where you can address one process to one cpu, and manage your processes... But, for instance, the kernel scheduler can, in case of an important load of CPU, switch a process to one CPU to another (called CPU Switch). But doing that too much often can reduce performances, because the cache of the processor is cleaned each time a process change CPU. This also can be modified with a kernel parameter called "timeslice", by default at 10ms.

PJA.

Re: cpu and process problem

Bill McNAMARA_1 — Fri, 26 Oct 2001 08:00:55 GMT

http://forums.itrc.hp.com/cm/QuestionAnswer/1,,0xad97663ce855d511abcd0090277a778c,00.html

Later,
Bill

Re: cpu and process problem

G. Vrijhoeven — Fri, 26 Oct 2001 08:21:04 GMT

Hi,

Like others have mentioned PRM is an option.
If you do not have PRM you can work with (re) niced processes. (man nice)

This will slow down the rate that the schedular promotes the processes.

Hope this will help.

Re: cpu and process problem

Santosh Nair_1 — Fri, 26 Oct 2001 08:43:35 GMT

PRM is nice, but I don't believe it does what Haiyu wanted, i.e. move processes from one CPU to another. PRM guarantees that a process has a defined percentage of CPU, but again, does not say that it will get its own CPU. The only way to ensure that a process has its own CPU is to set the processor affinity within the program. Of course this will require that you have the source code, an understanding of the code and a compiler.

Hope this helps.

-Santosh