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

[Mathieu Desnoyers]

* 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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-- 
Mathieu Desnoyers
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