[SR-Users] 100% CPU usage after NTP date update

[Daniel-Constantin Mierla]

Hello,

thanks for troubleshooting this issue.

Can you make a pull request on github.com kamailio project? Then we can
review and analyze better the impact. Ultimately, we can make this a
config options, as i think it is something good to have. The option
could be the value after which the delta is ignored (because is too big)
and timers jumps to execute current ticks.

Cheers,
Daniel

On 28/10/15 16:59, Stefan Kohlhauser wrote:
> Hello Daniel!
>  
> We have managed to track the problem down.
> What causes our troubles lies in the file timer.c in the function
> timer_handler.
> Or to be more exact in the for-loop:
>  
> for (prev_ticks=prev_ticks+1; prev_ticks!=saved_ticks; prev_ticks++)
>   timer_run(prev_ticks);
>  
> In our case, after the NTP time change, this tries to bring the
> prev_ticks (representing the year 1970) up to the saved_ticks (our
> current time provided by NTP) tick by tick.
> This is quite some calculating for 45 years. Especially on an embedded
> device.
>  
> As a workaround we have added an additional if-clause in the
> adjust_ticks function that simply ignores if the 'delta' between
> system time and ticks gets too high.
> We have run a first test where this workaround seems to be ok but
> we'll run some further tests.
>  
> Do you think this workaround might cause some problems? I.e. might
> there be a problem if the system time jumps ahead too far but we do
> not adjust the ticks?
> (We hope not because a time-leap backwards is ignored too :) )
>  
> Apart from our workaround:
> Do you think there might be a way to handle this problem less CPU
> consuming (or to bring the ticks up to date in a bigger bulk)?
>  
> Best regards,
> Stefan
>
>
> *Gesendet:* Donnerstag, 22. Oktober 2015 um 09:50 Uhr
> *Von:* "Daniel-Constantin Mierla" <miconda at gmail.com>
> *An:* "Kamailio (SER) - Users Mailing List"
> <sr-users at lists.sip-router.org>
> *Betreff:* Re: [SR-Users] 100% CPU usage after NTP date update
> Hello,
>
> can you do 'top' and see what is the pid of the process using a lot of
> cpu, then get the backtrace with gdb?
>
> gdb /path/to/kamailio PID
> bt full
>
> It will help to see what kamailio is trying to do.
>
> Cheers,
> Daniel
>
> On 22/10/15 10:45, Stefan Kohlhauser wrote:
> > Hello everyone!
> >
> > Setup:
> > I am currently using a Kamailio 4.2.3 on an embedded device (low CPU
> and RAM). The device is not able to store the current date, so after a
> reboot its 1. Jan 1970 until NTP updates the date.
> >
> > Problem:
> > If the date is updated after the Kamailio has started (a leap of 45
> years) the Kamailio uses up all the CPU and renders the device useless
> for a very long time.
> >
> > Notes:
> > There are no incomming requests at the time. (But the Kamailio is
> not responsive during that time anyway.)
> > Adjusting the internal Kamailio-time seems to take longer when the
> date update leap is bigger.
> >
> > My questions:
> > 1) Can I prevent the Kamailio from using up the entire CPU after a
> date update? Or maybe do the internal ticks-update more gracefully?
> > 2) For my better understanding: What happens within the Kamailio
> after adjust_ticks has updated the internal date?
> >
> > Thanks in advance for your help!
> >
> > Best regards,
> > Stefan
> >
> > _______________________________________________
> > SIP Express Router (SER) and Kamailio (OpenSER) - sr-users mailing list
> > sr-users at lists.sip-router.org
> > http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-users
>
> --
> Daniel-Constantin Mierla
> http://twitter.com/#!/miconda <http://twitter.com/#%21/miconda> -
> http://www.linkedin.com/in/miconda
> Book: SIP Routing With Kamailio - http://www.asipto.com
>
>
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-- 
Daniel-Constantin Mierla
http://twitter.com/#!/miconda - http://www.linkedin.com/in/miconda
Book: SIP Routing With Kamailio - http://www.asipto.com
Kamailio Advanced Training, Nov 30-Dec 2, Berlin - http://asipto.com/kat

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