print kstat when updated (multiple times in 1 second)

Question

I am trying to gather statistics via kstat which I currently use dtrace to gather.

It is not count based information but new data every single time.

The minimum interval on kstat print is 1 second.However ,the data that I need changes several times within a second.Is there a way(API) to get data from kstat whenever the kstat is updated that doesn't use dtrace ?

Answer 1

Outside with dtrace, there is no way to get the statistics when they are updated however, the C libkstat API allows retrieving kstat statistics with an arbitrary sub second sampling rate.

There is also a perl api should you want to do it with scripting.

A very simple way to use it would be to create a customized kstat command (which happen to already be a perl script leveraging the kstat perl api) and modify it to use high resolution timers instead of the default one, e.g.:

$ sed '
s/sleep($interval);/Time::HiRes::usleep($interval*1000.);/
/use Sun::Solaris::Kstat/a\
use Time::HiRes;
' /usr/bin/kstat > /var/tmp/kstat_ms
$ chmod +x /var/tmp/kstat_ms
$ /var/tmp/kstat_ms -n lo0 500 3

module: lo                              instance: 0
name:   lo0                             class:    net
        crtime                          19.559031813
        ipackets                        532
        opackets                        532
        snaptime                        4309.506435597


module: lo                              instance: 0
name:   lo0                             class:    net
        crtime                          19.559031813
        ipackets                        534
        opackets                        534
        snaptime                        4310.008578348


module: lo                              instance: 0
name:   lo0                             class:    net
        crtime                          19.559031813
        ipackets                        536
        opackets                        536
        snaptime                        4310.511617682