[sr-dev] [Kamailio-Users] Fast lock loop with arm

[Daniel-Constantin Mierla]

Hello,

what version of kamailio do you use?

Can you grab a backtrace with gdb once you get this high cpu usage? Spot 
one of the processes, take the pid and do:

gdb  /path/to/kamailio  _pid_

Then:

bt

You should see the bactrace of executed function getting to deadloc. 
Make sure you get at least one SIP worker process backtrace (do kamctl 
ps to see the type of kamailio process).

Cheers,
Daniel

On 3/24/10 4:29 PM, Zappasodi Daniele wrote:
>
> Hi,
> I have a big problem with fast lock mutex on arm CPU:
> sometimes I find one or more children that go in an infinite loop, in 
> the while loop of get_lock function.
> They remain in Run for long time (sometimes hours) and openser keeps 
> 100% CPU.
>
> Now I have changed the functions get_lock and tsl in order to obtain 
> more info and
> I observe that  (if and) when the process finish the cycle, it have 
> done a big amount of cycles.
>
> This the log with my added info:
> Mar 26 20:29:08 SAM-IP openser[1645]: NOTICE:tm:_lock: ret 1 (cycle)
> Mar 26 20:29:51 SAM-IP openser[1645]: NOTICE:tm:_lock: ret 1 (cycle)
> Mar 26 20:29:55 SAM-IP openser[1645]: NOTICE:tm:_lock: ret 1 (cycle)
>
> Mar 26 20:29:55 SAM-IP openser[1645]: NOTICE:tm:t_retransmit_reply: 
> MYTM lock
> [process in loop]
> Mar 26 20:33:46 SAM-IP openser[1645]: NOTICE:tm:_lock: ret 59374917 
> (cycle)
> [after 4 minutes and 59374917 cycles, this is an example with a 
> "short" loop]
> Mar 26 20:33:46 SAM-IP openser[1645]: NOTICE:tm:t_retransmit_reply: 
> MYTM lock done
>
> I'm not able to recognize the call flow that generates the loop (I 
> know only that it always happens when t_retransmit_reply calls 
> LOCK_REPLIES),
>
> but I urgently need a work around to escape from the loop.
>
> This is the get_lock function with my counter j:
>
> inline static int get_lock(fl_lock_t* lock)
> {
> #ifdef ADAPTIVE_WAIT
> int i=ADAPTIVE_WAIT_LOOPS;
> int j=1;                                        /***** my change ****/
> #endif
>
> while(tsl(lock)){
> #ifdef BUSY_WAIT
> #elif defined ADAPTIVE_WAIT
> j++;                            /***** my change ****/
> if (i>0) i--;
> else sched_yield();
> #else
> sched_yield();
> #endif
> }
> return(j);
> }
>
> Can I break the lock when my counter reaches a big value?
> Should I call the unlock function after the break?
> which value can be considered too big?
>
> Thanks,
> Daniele
>
>
>
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-- 
Daniel-Constantin Mierla * http://www.asipto.com/
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