[Kamailio-Devel] Kamailio Timer Accuracy

[Jason Penton]

Hi Henning,

Thanks for the effort, I was testing specifically in the dialog module, in
the function get_expired_dlgs of dlg_timer.c

I will check with usrloc and get back to you but in the meantime i have
changed the code to use epoch instead of ticks and it is accurate now.

I am running solaris 10 update 4, synched to ntp server

thanks again
Jason



On Thu, Sep 25, 2008 at 11:09 AM, Henning Westerholt <
henning.westerholt at 1und1.de> wrote:

> On Wednesday 24 September 2008, Jason Penton wrote:
> > yes a 1s interval timer registered through the timer API. I then count
> the
> > ticks corresponding to 5 mins (current ticks + (5*60)). At the end the
> > stopwatch (wallclock) reads 5min and 20 secs. My question is what the
> > impact on for example the Dailog module which relies on these timers for
> > timeouts, etc. A timeout on a dialog of for example 3600 will be horribly
> > out.
>
> Hi Jason,
>
> i tried to reproduce this inaccuracy with the usrloc timer on my machine
> this
> morning. I setup them to an 1 second interval, and let them run for 30
> minutes. I incremented a counter in the function, to keep track of the
> seconds, and also used an external stopwatch.
>
> I could not reproduce the problem you described:
>
> Sep 25 10:31:54 ca ../kamailio[16490]: ERROR:usrloc:timer: timer tick 0
> Sep 25 10:32:55 ca ../kamailio[16490]: ERROR:usrloc:timer: timer tick 60
> Sep 25 10:41:55 ca ../kamailio[16490]: ERROR:usrloc:timer: timer tick 600
> Sep 25 10:51:55 ca ../kamailio[16490]: ERROR:usrloc:timer: timer tick 1200
> Sep 25 10:59:56 ca ../kamailio[16490]: ERROR:usrloc:timer: timer tick 1680
> Sep 25 11:01:56 ca ../kamailio[16490]: ERROR:usrloc:timer: timer tick 1800
>
> This step of about 1 seconds is probably caused from the linux timer
> resolution, wich is 1ms on 2.6 kernels. This is also more or less visible
> on
> the stopwatch. I think this is a reasonable accuracy, given the usage of
> this
> timers.
>
> Do you use ntpc or chronyd to get a reliable time, and also sync the kernel
> clock on the test machine? Do you use a 2.6 kernel with the default HZ
> value?
> Perhaps you can also compare to the usrloc timer, here is the code i used:
>
> Index: modules/usrloc/ul_mod.c
> ===================================================================
> --- modules/usrloc/ul_mod.c     (revision 4991)
> +++ modules/usrloc/ul_mod.c     (working copy)
> @@ -375,12 +375,13 @@
>        destroy_ulcb_list();
>  }
>
> -
> +static unsigned int timer_tick = 0;
>  /*! \brief
>  * Timer handler
>  */
>  static void timer(unsigned int ticks, void* param)
>  {
> +       LM_ERR("timer tick %d", timer_tick++);
>        if (synchronize_all_udomains() != 0) {
>                LM_ERR("synchronizing cache failed\n");
>
>
> Cheers,
>
> Henning
>
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