High CPU Load on 64 Threaded Solaris System

[FunInTheSun]

Hi,

Newbie on here so please forgive me if I have broken etiquette or posted in the wrong place!

We have a system with 1 x 8 core CPU which is multithreaded to allow 64 threads. Regularly we are receiving High CPU Load notification of anywhere between 10 & 12.

I guess what I want to know is 'is this actually a problem or is the Load too low to worry about'? At what point should we start to investigate\worry about this?

Many thanks.

 

[Annihilannic]

Is that the load average you are referring to, as reported by uptime?

If so, 10 or 12 is fine on an 8 core CPU. I'm not sure what you mean by "multithreaded to allow 64 threads". You can't multithread a CPU... you can multithread some software though, is that what you mean?

As a rule of thumb I would consider a load average greater than 2 x #cores to be "high". This equates roughly to every CPU being busy running one process, and every CPU having one process queued, on average.

Annihilannic.

 

[SamBones]

Yeah, what is the "10" & "12" you're reporting? How are you getting that number? what is giving you that notification?

The "sar" command will give you some detail. The command "sar" by itself will give you CPU usage. That's the first thing to look for. If CPU looks reasonable, the command "sar -q" will give you run queue information. Anything over 1.0 for runq-sz (Run Queue Size) with a %runocc (Percent of Time Occupied) over 0 means processes are waiting for CPU. That means that no matter how many threads your machine can handle, it isn't keeping up with the demand for CPU.