topic Re: Getting current utilization value of tunable kernel parameters in Operating System - HP-UX

Getting current utilization value of tunable kernel parameters

Tom Krocak_1 — Thu, 12 Jan 2006 14:56:38 GMT

I would like to be able to find out high water values for a number of kernel parameters NOT included in glance/gpm. There must be a counter that is kept in HPUX for parameters that have max values and that is the counter that I need to query to monitor how close to the maximum the current usage is. Does anyone know how to do this, hopefully usable in a script or other programmatic way?

Re: Getting current utilization value of tunable kernel parameters

Ivan Ferreira — Thu, 12 Jan 2006 15:05:37 GMT

Is it kmtune -l what you are looking for?

For example:

Tunable vxfs_bc_bufhwm
Description VxFS metadata buffer cache high water mark
Module vxfs
Current Value 0 [Default]
Value at Next Boot 0 [Default]
Value at Last Boot 0
Default Value 0
Constraints vxfs_bc_bufhwm == 0 or vxfs_bc_bufhwm >= 6144
Can Change At Next Boot Only

Re: Getting current utilization value of tunable kernel parameters

Dave Hutton — Thu, 12 Jan 2006 15:24:10 GMT

Which version of hpux?

11.23 you can use kcusage to see the current values and probably could parse out the information you want.

Re: Getting current utilization value of tunable kernel parameters

Tom Krocak_1 — Thu, 12 Jan 2006 15:25:20 GMT

No, kmtune only returns the current value of the parameter (i.e. max value) not the current utilization of the parameter. For example, for "nfile", we have a parameter value of 70732. Glance and MeasureWare report the current utilization towards this max value. For the nfile, we see utilization of 51682 (for example), well below the max kernel parameter, so we know we are OK for now. We have also looked at "sysdef" and "tuneinfo", but these provide similar information as kmtune and not the utilization values at the time of measurement.

Re: Getting current utilization value of tunable kernel parameters

Tom Krocak_1 — Thu, 12 Jan 2006 15:28:53 GMT

We are on version HPUX 11.11. I couldn't find a "kcusage" on our system.

Re: Getting current utilization value of tunable kernel parameters

A. Clay Stephenson — Thu, 12 Jan 2006 15:32:27 GMT

sar -v will report the number of files in use but to do this on a tunable by tunable basis is a far from trivial exercise --- and is not even meaningful of possible with a number of tunables. Probably your least evil approach is running Glance in -advisor_only mode looking for a number of parameters.

Re: Getting current utilization value of tunable kernel parameters

Sundar_7 — Thu, 12 Jan 2006 15:39:58 GMT

Tom,

you can use adb to get some of this information

# adb64 -k /stand/vmunix /dev/kmem
$> /tmp/something
$e
$q
#

# grep nfile /tmp/something

- Sundar

Re: Getting current utilization value of tunable kernel parameters

Tom Krocak_1 — Thu, 12 Jan 2006 16:40:31 GMT

Sundar,
I tried the "adb64" command as you gave it and searched the output file. For nfile and nflocks, the values given were the same as the max parameter (in hex), not the current usage value. This file doesn't appear to have actual usage towards the max values.
------------
Clay,
I would need a quick primer on how to use glance in "advisor_only" mode, but doesn't this just report on actual metrics recorded by measureware? The only related metrics in MW are those beginning with "TBL_" and there are only 8 of these for HPUX, the same ones reported by "glance -t".

Re: Getting current utilization value of tunable kernel parameters

Don Morris_1 — Thu, 12 Jan 2006 17:26:36 GMT

It's going to vary widely by what tunable you're talking about and unless you use supported APIs [not adb to guess kernel variables] it can change with patches.

For nfile, you want pstat_getdynamic(). psd_activefiles is the field within there which is the current number of active file table entries (which is what nfile bounds). Similarly, nproc's usage is reflected in psd_activeprocs, etc.

Re: Getting current utilization value of tunable kernel parameters

Tom Krocak_1 — Thu, 12 Jan 2006 17:44:01 GMT

Don,
I checked the adb log file and there were no such variables (xxx.psd_activefiles, etc) in there. We don't have any of the special API's installed, so perhaps we are barking up the wrong tree using this approach.

Re: Getting current utilization value of tunable kernel parameters

Don Morris_1 — Thu, 12 Jan 2006 18:09:24 GMT

Those aren't global kernel variables, they are fields in the structure passed to/from the user space pstat_getdynamic() system call.

Trust me, you have pstat(). Read pstat(2) for more details.

Here's an example (ignore the horrid formatting -- I'm not going to figure out how to get this web interface to tab nicely... :) ):
# cat nfile_usage.c
#include
#include
#include
#include

int
main(int argc, char **argv)
{
struct pst_dynamic psd;
int rv;

rv = pstat_getdynamic(&psd, sizeof(struct pst_dynamic), 1, 0);

if ( rv > 0 ) {
printf("Number of files in use: %ld.\n",
psd.psd_activefiles);
} else {
printf("pstat_getdynamic failure: %d.\n", rv);
}

exit(0);
}

Compiled with:
# cc +DD64 -D_PSTAT64 -o nfile_usage nfile_usage.c
# ./nfile_usage
Number of files in use: 307.

Not every kernel tunable usage can be easily determined -- a list of the ones you want would be helpful.

Re: Getting current utilization value of tunable kernel parameters

Tom Krocak_1 — Fri, 13 Jan 2006 11:46:26 GMT

Don,
GREAT! It works (needed to tweek code since we must have a gnu C compiler rather than an ANSI compiler).

Our Progress DBA wanted to know high water usage values for the following kernel parameters in addition to those reported in glance/MW:
shmseg, shmmax, semmsl, semmns, semmnu, msgmap, msgmax, msgmnb, msgmni, msgseg, msgssz, msgtql.

Thanks - Tom

Re: Getting current utilization value of tunable kernel parameters

Jeff Schussele — Fri, 13 Jan 2006 11:51:17 GMT

Hey Tom,

That was a pretty elegant solution.
Throw the guy bone - assign points.
It's the right thing to do.

Jeff

Re: Getting current utilization value of tunable kernel parameters

Raymond Kelly — Tue, 27 Jun 2006 13:40:23 GMT

Don,

This looks like a very useful script, unfortunately, I am not able to compile it.
Apparantly, my compile does not like the following line:
main(int argc, char **argv)

Is there no other way to get this info?

I am not sure which compiler we are using (I'm pretty new to this).

Any help would be appreciated.

Raymond

Re: Getting current utilization value of tunable kernel parameters

Tom Krocak_1 — Thu, 06 Jul 2006 10:27:59 GMT

As I noted, I also had to make a few changes in the "c" code to make it work - in the same area you had problem. The changes I made are below and them I was able to compile and run the program:

int
main ( argc, argv )
int argc;
char **argv;

(The code before and after are the same)

Unfortunately, most of the kernel highwater values are not available under HPUX 11.11. I found this out when I called HP. They said that more of these are available under 11.23

Re: Getting current utilization value of tunable kernel parameters

Bill Hassell — Thu, 06 Jul 2006 11:52:40 GMT

> Our Progress DBA wanted to know high water usage values for the following kernel parameters in addition to those reported in glance/MW:
shmseg, shmmax, semmsl, semmns, semmnu, msgmap, msgmax, msgmnb, msgmni, msgseg, msgssz, msgtql

Many of these parameters are limits or fences so they are not 'consumed' like nfile or nproc. Therefore, there is no concept of a highwater mark. If a program asks for a shared memory segment that is less than shmmax, then the program works. If it asks for more than the limit, the call fails. The best solution is to use ipcs (with lots of options) to monitor IPC metrics.