[ltt-dev] Flight-recording mode

[Mathieu Desnoyers]

* Gerlando Falauto (gerlando.falauto at keymile.com) wrote:
> On 10/28/2011 09:39 AM, Mathieu Desnoyers wrote:
>> * Gerlando Falauto (gerlando.falauto at keymile.com) wrote:
> ...
>>> How can I make sure that only the latest N seconds of traces will be
>>> saved? The answer should be flight-recording mode, but how do I really
>>> do it?
>>
>> I discussed this with David this morning, and we'll need to enhance
>> ltt-sessiond in lttng-tools to ensure it does not send the streams to
>> the consumer daemon upon trace start for overwrite mode channels, but
>> just on trace stop. This is lacking currently.
>
> OK, thanks!
> Does that also apply to LTTng 0.x (since I got the same impression)?
>
> For 0.x I came up with the idea of killing lttd but I don't know if
> a) it's a good idea;
> b) it would do the trick

for 0.x it should all just work (TM) ;)

by specifying flight recorder mode, lttctl is supposed to launch lttd
only on non-overwrite mode buffers (metadata) first, and only upon trace
teardown does it hook lttd on the flight recorder buffers.

Please let us know how it works for you.

Thanks,

Mathieu

>
> Thanks!
> Gerlando
>

-- 
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com