[asterisk-dev] RTP streams suddenly stop

[Shaun Ruffell]

On 03/29/2010 11:03 AM, Tony Mountifield wrote:
> In article <hm3o5a$mno$1 at softins.clara.co.uk>,
> Tony Mountifield <tony at softins.clara.co.uk> wrote:
>>
>> My main question at the moment is "what mechanism could stall all RTP streams?",
>> and a clue is the almost-exact five minutes for which it happens.
> 
> Well, FINALLY, I have managed to discover what is causing this problem,
> although I haven't yet fixed it.
> 
> The problem is in ztdummy. It is the one from zaptel-1.2.27, and has been
> compiled with USE_RTC. The OS is CentOS 4 with kernel 2.6.9-78.0.22.ELsmp.
> The system has a pair of quad-core E5420 Xeons.
> 
> By monitoning /proc/interrupts every second, I have discovered that when
> the problem occurs, the RTC interrupts stop counting up. After exactly
> five minutes, they start up again. Obviously the lack of timing from
> ztdummy is causing Meetme and file streaming to stall.
> 
> So, does anyone have any ideas why the RTC interrupt might stall for exactly
> five minutes? I have only ever seen it on this one system. Nothing is logged
> in any of the system logs at the time it occurs.
> 
> I would quite like to try the HPET mode of ztdummy, but it looks like this
> requires a much newer kernel, 2.6.22, which is way newer than even CentOS 5.
> Is there any other way to do this?

I noticed this as well when looking at issue 13930 [1]. Perhaps instead of using the HPET timer, you could back port the changes in dahdi_dummy that makes the default kernel timer usable (assuming you can't update)?

Best guess as to why it might stop though is probably ntp or something is running on that system, and it gets out of sync, then 5 minutes later when the kernel tries to sync back the time, it gets kicked off again.  Don't quote me on that..just a guess.

[1] https://issues.asterisk.org/view.php?id=13930#99444

-- 
Shaun Ruffell
Digium, Inc. | Linux Kernel Developer
445 Jan Davis Drive NW - Huntsville, AL 35806 - USA
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