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LOAD AVERAGE on HP-UX SMP

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Roman Sustek
Occasional Contributor

LOAD AVERAGE on HP-UX SMP

Hi, I'd like to ask how load average is represented on HP-UX on a multiprocessor system. Below is an output of top command on 4-processor system. Uptime and w commands give the same numbers as the first line in the top output.

The problem is this: Documentation says that load average is the number of all active processes. But in the output it seems that it's divided by the number of processors. Is this standard for HP-UX?

My second question is: if it is really divided by #processors, what LOAD means for the particular processors - does each processor have its own queue? I doubt it. How it is calculated? Does anyone have an explanation for this?

Load averages: 1.75, 1.12, 1.00
472 processes: 412 sleeping, 59 running, 1 zombie
Cpu states:
CPU LOAD USER NICE SYS IDLE BLOCK SWAIT INTR SSYS
0 1.69 62.0% 5.0% 30.5% 2.6% 0.0% 0.0% 0.0% 0.0%
1 1.72 47.0% 20.7% 29.1% 3.2% 0.0% 0.0% 0.0% 0.0%
2 1.78 61.0% 9.8% 27.7% 1.6% 0.0% 0.0% 0.0% 0.0%
3 1.80 65.9% 8.0% 23.9% 2.2% 0.0% 0.0% 0.0% 0.0%
--- ---- ----- ----- ----- ----- ----- ----- ----- -----
avg 1.75 59.1% 10.8% 27.7% 2.4% 0.0% 0.0% 0.0% 0.0%



5 REPLIES
Horia Chirculescu
Honored Contributor

Re: LOAD AVERAGE on HP-UX SMP

Hello,

>Documentation says that load average is the >number of all active processes.

This is not true. I doubt you have found somewhere in the docs (both HP-UX or for any UNIX) such an affirmation.

The load average is the average number of processes in the queue waiting
for CPU time, over the last 1, 5, and 15 minutes.

Best regards,
Horia.
Best regards from Romania,
Horia.
Roman Sustek
Occasional Contributor

Re: LOAD AVERAGE on HP-UX SMP

Thanks for the answer. OK, it might be true since the first source I checked was wikipedia. But, the second question stays? Why each processor has its own load average? What do these numbers represents?
Don Morris_1
Honored Contributor
Solution

Re: LOAD AVERAGE on HP-UX SMP

Because each processor has its own run queue. (I don't know why you doubt it). So the average load reported per processor is exactly that.

http://docs.hp.com/en/5965-4643/ch01s13.html

Implicit to some extent by the fact that you can create a pset with a single processor.
Roman Sustek
Occasional Contributor

Re: LOAD AVERAGE on HP-UX SMP

OK, thanks. That explains it. I wasn't sure about more queues because somebody told me that this is called CPU Affinity and is used rarely.
morpheus_online
Occasional Visitor

Re: LOAD AVERAGE on HP-UX SMP

Hi guys, i´m still confused about load averages. Maybe is because i´m trying to make a relation with load averages of command "top" and enqueuing runing processes from "vmstat" column (r).

He is the think, we have a server with 6 cpu´s, and with top command i can see that "load averages" is always between 2 to 4... and at the same time if a prompt for example: "vmstat 1 100", i see that column (r) is with 20 to 30 processes in waiting, cpu with 85% to 98% usage, and idle 0 to 10, ok? This is the fact!

So, what I would like to know is, if there is a relation between these commands and information?

And how can I surely see the enqueue processes?

Could someone help please?

Thanks!