How to reduce the %sys in sar -u output

[Nagarathinam]

Dear HP experts,
Happy christmas.
With guidance and help from forum members, I am able to tune my HP R380/HP-UX B11.00. Now, in my 'sar -u' output I see the following.

%usr %sys %wio %idle
3 17 7 73

This is the average.

I want to know, is there a possibility to improve the system by reducing the %sys. if so, How it can be done ?

one piece of additional information is,
* this machine is a node of a cluster
* I am at this time connected with 25 users concurrently.
* response to users is good.

Can anybody helpme in this regard,

with thanks

Naga

[Ian Dennison_1]

The 2 questions would be 'what is causing the excessive system mode' and 'Is this normal?'

Have you checked vmstat, to see if paging is taking place? What about 'sar' reporting on '%wio'? Glance will provide a very good subset of information per process on their modes.

Share and Enjoy! Ian

[Andy Zybert]

I wish I had a system that looked like this. I normally would not get concerned with this usage until > 50% was in use.

In order to lower the % sys metric you would need to identify what activity is causing process/es to spend the time in kernel.

The standard top, glance, gpm performance analysis tools would be the first step to identify the process. You can then further drill down in to system calls/context switches that are being made.

Excessive 'CPU interrupt' activity > 30% would point to an I/O bottleneck. In which case check disk usage/IO cards first.

Memory problems can also come disguised as % sys usage; if the system is > 95% used and paging/deactivations are occurring. The f/s buffer cache may also be set too large, default settings of 50% memory can normally be reduced. (300-400Mb for the F/s cache is usually large enough)

Cheers

AndyZ

[Nagarathinam]

I have done the following
* checked vmstat and found no paging
* checked %wio is 7%
* TOP is run and found that CPU activity is around 17%
* there is no waiting due to disk activity ( checked through sar -d )
* kernel parameters were set dbc_max_pct to 15 and dbc_min_pct to 5 prior to this

I hope these things are normal.

Further inputs are welcome

Naga

[John Waller]

I can't really comment too much as I don't know what applications you are running, but on my own systems I normally see an higher %usr then %sys. Do you have a database or some other application which runs as user root. Normally a high %sys means a lot of processes running as root.
In reality I shouldn't be too worried though, a 73% idle figure shows the system still has plenty of power still available.

[harry d brown jr]

Naga,

If you are running ems, it'll consume about 10% of your system resources.

The best way to determine "what" is consuming your resources is to run glance (measureware). You need a license to get the full show, but you can install a trial version (good for 30 days) from your application CD's (The first one I believe).

live free or die
harry

[Bill Hassell]

There's nothing wrong with high values for %sys. The operating system consumes virtually no CPU when no programs are running, so you can safely assume that the system load is directly related to the programs that you are running. Having 50% system load would be quite normal in a system that responds to tens of thousands of I/O's per second (often see with Xwindow programs that do polling).

So there is nothing to fix in HP-UX even if the system load grows way beyond 50%. Instead, you need to identify the process(es) that contribute to this high load. A very simple (badly written) program can uselessly consume system time by asking the time of day in an endless loop.

[Roger Baptiste]

Hi,

<<%usr %sys %wio %idle
3 17 7 73

This is the average. >>

Hey, it is 73% idle. Chill out, relax ;-)
For a node in a cluster with 25 users, it is
a decent stat.

You would need to be concerned with a sys
value which goes consistently around the value of 50% and when the idle time is almost Zero.
Generally, it would happen with swapper/vhand
running in sys mode. But, not in this case, since the system is almost idle.

HTH
raj