[ltt-dev] Multi-second gaps in trace events

[Chad Willman]

No dmesg warnings about either of these.

I haven't done anything specific with the buffer size. Let me know if I just
need to RTFM.

I'm running in "flight" mode, which I believe is overwrite.

Chad


On 9/30/09 12:44 PM, "Mathieu Desnoyers" <compudj at krystal.dyndns.org> wrote:

> OK. Then, other question, do you have warnings in your traced board
> dmesg telling that you have "lost subbuffers" or lost events ? This is
> shown right after tracing stops. (newer LTTng has this warning shown in
> LTTV, but your old LTTng/LTTV combo doesn't)
> 
> Your buffer size may be too small.
> 
> Are you tracing in "overwrite" or "non-overwrite" mode ?
> 
> Mathieu
> 
> * Chad Willman (cwillman at lifesize.com) wrote:
>> 
>> Thanks for the reply.
>> 
>> Yes, it's an ARM, but it has a cycle-counter and we've actually added
>> support for it to LTTng. We get nanosecond resolution.
>> 
>> Chad 
>> 
>> 
>> On 9/30/09 12:29 PM, "Mathieu Desnoyers" <compudj at krystal.dyndns.org> wrote:
>> 
>>> * Chad Willman (cwillman at lifesize.com) wrote:
>>>> 
>>>> I¹m seeing long (multi-second) gaps in trace events and am wondering if
>>>> this
>>>> is a known issue.
>>>> 
>>>> For example, trace events shown in the viewer appear normal and then
>>>> suddenly there will be a gap of 9 seconds (varies) where it appears that a
>>>> single thread is running in user mode (green) and nothing else is happening
>>>> on the entire system in any thread for 9 seconds (no context switches, . .
>>>> .
>>>> nothing).
>>>> 
>>>> This is an excellent tracing facility, but I can¹t rely on it entirely
>>>> until
>>>> I have no gaps in the trace. Any ideas ?
>>>> 
>>>> I¹m running -
>>>> Lttng v 0.6.33 on Linux 2.6.18 kernel on a TI DaVinci DM6467T SOC platform
>>> 
>>> That's an ARM board right ?
>>> 
>>> On these boards, LTTng has a 1 jiffy precision, because it uses the
>>> "generic clock". Within this interval, events are simply counted, e.g. 1
>>> cycle = 1 event.
>>> 
>>> The ARM OMAP3 has cycle counters, which LTTng uses.
>>> 
>>> Mathieu
>>> 
>>>> Ltt-control v 0.30
>>>> Lttv v 0.8.72
>>>> Genevent v 0.30
>>>> 
>>>> Regards,
>>>> 
>>>> CW
>>> 
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>>> 
>>