[ltt-dev] LTT : cpu : 32043 events lost in cpu channel (cpu 1).

[ltt-dev] LTT : cpu : 32043 events lost in cpu channel (cpu 1).

[Gian Lorenzo Meocci]

Hi all,

I am trying to trace x264 code with a SCHED_RR policy for all threads.
When I use this policy or SCHED_FIFO policy I always obtain this
error:

LTT : cpu : 32043 events lost in cpu channel (cpu 1).

I am using:
Linux 2.6.27.4-profiled #2 SMP Fri Nov 7 14:17:36 CET 2008 i686 GNU/Linux
Linux Trace Toolkit Trace Daemon 0.57-28102008
Linux Trace Toolkit Visualizer 0.11.5-06112008


Thanks a lot,

-- 
Ing. Gian Lorenzo Meocci
http://www.meocci.it

[ltt-dev] LTT : cpu : 32043 events lost in cpu channel (cpu 1).

[Mathieu Desnoyers]

* Gian Lorenzo Meocci (glmeocci at gmail.com) wrote:
> Hi all,
> 
> I am trying to trace x264 code with a SCHED_RR policy for all threads.
> When I use this policy or SCHED_FIFO policy I always obtain this
> error:
> 
> LTT : cpu : 32043 events lost in cpu channel (cpu 1).
> 
> I am using:
> Linux 2.6.27.4-profiled #2 SMP Fri Nov 7 14:17:36 CET 2008 i686 GNU/Linux
> Linux Trace Toolkit Trace Daemon 0.57-28102008
> Linux Trace Toolkit Visualizer 0.11.5-06112008
> 

Try

- Increasing the buffer size (see high event rate buffer size in lttctl
  --help) or the number of subbuffers. Note that those are both rounded
  to the next power of two.
- Running in flight recorder mode. You would then have only the last X
  events from the trace, but you won't be limited by your disk output.
- Having a faster disk output.
- Looking at the most frequent events in the trace and disabling this
  instrumentation. using lttv -m textDump --noevent path_to_trace
  should help finding the most frequent event.

Mathieu

> 
> Thanks a lot,
> 
> -- 
> Ing. Gian Lorenzo Meocci
> http://www.meocci.it
> 
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> 

-- 
Mathieu Desnoyers
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