11iv3 automatic kernel tuning

[Olivier Masse]

Does anybody here have experience with auto-tuning of kernel parameters with 11iv3?

On a 11iv3 test server, nflocks was set to its default value of 4096 with Changes to "Auto" and "Can Change" enabled. But stressing the server voluntarily with our custom app resulted in nflocks getting exhausted and the app crashed. Kcusage shows me that nflocks went up to 99.6% and the value obviously didn't grow as it should.

I cite here the manual:
"Still others can be automatically tuned, which means that the default value can change periodically while the system is running, in response to changing system resources and needs."

I've never seen this work with 11iv2 and decided to configure manual values. Looks like I don't have success with 11iv3 either. Anyone been able to make this work?

Thanks

[Duncan Edmonstone]

Olivier,

I thought when a kernel tunable was automatically managed it was basically removed as a tunable altogether... so what is partly described in the man page for kctune looks a little unclear to me.

did you get a "y" for all 3 settings that need to be on for auto tuning?

# kctune -P default,auto_default,canauto nflocks
default y
auto_default y
canauto y


HTH

Duncan

[Olivier Masse]

Yep, I get all three y's there.

[Steven E. Protter]

Shalom,

I would not permit any auto tuning at all happen on my systems.

The methodologies used by developers as proven by their formulas simply do not hold up in the real world.

There is no replacement for a good systems administrator.

SEP

[Norman Dignard]

I also noticed in 11v3 there is a tuneserver
exec that sets certian kernal parms (/opt/tuneserver). I have not used this but am wondering if anyone else has used this and what were the results?

[Olivier Masse]

tuneserver sets standard parameters which are suitable for an Oracle or Java workload. I checked them, and it covers 99% of the parameters I used to tune by hand before (except nflocks, which is kept to auto, thus my question here).