CPU load balancing

[Jeffry Tank]

I was wondering if there is some way to distribute the CPU load evenly across multipul CPU's in an N Class server. In all my N Class servers the oracle processes seem to load one or two CPU's while the rest remain mostly idle. I have several servers with 4 to 8 CPU's and 8 to 12Gig of memory. All system are runing HPUX 11.X and Oracle 8.1.7 and 9i databases.

Thanks in advance

Jeff

[Pete Randall · Accepted solution]

Jeff,

That's what HP-UX attempts to do. I don't think there's any further tuning that can be done, unless it's to your Oracle engine.

Pete

[Bill Hassell]

There is no way to spread the load of one program across multiple CPUs. That's because each instruction must be executed in order. If separate CPUs ran different instructions, the result would be chaos. Applications must be specifically written to handle multiple CPUs. This technique is called threading and is similar to writing mini programs within a single application.

These threaded applications can take advantage of multiple CPUs as each mini program runs by itself and signaling the main program when it is done. An example of a threaded application is a web browser like Netscape, Opera or IE. While downloading a web page, the mouse still works and can pull down menus or change the current URL. To do this, the browser must run a separate task to perform the download, another to monitor mouse clicks, another to pull down a menu and so on.

In the case of Oracle, conact your DBA to look at the configuration file and version. Sone versions od Oracle can take advantage of multiple processors when the startup config file specifies the number of parallel tasks that can be run at the same time.

[Ian Dennison_1]

Jeff,

In terms of multi-threading, you will probably require a re-design of that way your Oracle System does its work.

FYI, we benchmarked our (ahem) 'multi-threaded', in-house developed Oracle 8.1.7.3.0 App on a 32-CPU Superdome last year. After the initial benchmark run, we dropped the number of CPUs down and re-ran it again. It was only when we got down to 8 CPUs that the program started to run in a longer time (12 CPUs provided all the resources Oracle could use).

Ergo, even though an Oracle system may be designed to be multi-threaded, you may still run into some design flaws that prevent usage of the available hardware / OS resources.

Maybe Oracle 9i has some tweaks for this (partitioning perhaps?)

Share and Enjoy! Ian

[Jeffry Tank]

Thanks all
this is what I suspected but I wanted to make sure I was correct in my asumptions before presenting it to my boss as he was concerned that there may have been other problems that would cause this behavior.

Jeff Tank

[Rory R Hammond]

Jeff,

When I investigate these types of problems on our system. I look at the dominating CPU process using Oracle's Top Session and sometimes SQL analyze. We have fixed many performance problems by adding and Index or by rewriting a query. Some times we just have to pass on the issue to the developer and he fixes it.

[Tim D Fulford]

Hi

We use Informix. Informix has a basic "work horse" process termed cpu-vp. In HP-UX it just appears as a process "oninit", but the general rule of thumb is number of CPU-1 = number of cpu-vps. Informix will spread the load over these cpu-vps and HP-UX will try to run each oninit on a processor. Informix actually has quite a few vps (virtual processes)
but generally a cpu-vp is by far the busiest.

I know you use Oracle, but there is probably a similar class of process, it may be that you could run more "work horse" processes.

Regards

Tim

[Paula J Frazer-Campbell]

Jeff

Please assign points, as these forum members have gone out of their way to assist you.


Paula

[Tim D Fulford]

Try looking at ....

mpsched -c cpu# -p pid

I can't find the command on my system, but it is only a 1CPU machine, I just happened to see this today and thought of you (ahhh!!!)

Tim

[RAC_1]

If you have multiple Oracle instances running on your system you may consider installing PRM(Process Resource Manager)

Basically with PRM installed you can allot CPU,MEM,DISK to different groups.(These groups you define in config file)

We run PRM with CPU allocation in SHARE mode.
With this we can allocate 50 % of CPU(all CPUs) power to this progrm another 30 % to another programm and likewise.

Check documents at docs.hp.com for detailed information on PRM.