Re: Flight recorder mode

Mathieu Desnoyers wrote:
> Ah, am I dumb... sorry..
> 
> to take a flight recorder trace, making sure everything is read
> correctly :
> 
> armall
> lttctl -n trace -c -m flight
> lttd -n -d -t /tmp/trace -c /sys/kernel/debug/ltt
> lttctl -n trace -s
> .. do stuff
> lttctl -n trace -q
> lttd -f -d -t /tmp/trace -c /sys/kernel/debug/ltt
> lttctl -m trace -r
> 
> This should work also for hybrid traces if you replace -m flight with -m
> hybrid.
> 
> Maybe I should adapt lttctl so we can use it in the same way for hybrid
> and flight recorder traces without calling lttd explicitly.

What would be even nicer (considering our old, custom setup) is lttd in
standby until someone issues a trace stop, via lttctl or directly from
some application that detected a trace-worthy event. Then the daemon
should dump the flight channels and terminate. A script could catch
this, archive the trace, and even restart the whole thing if desired.

OK, that may not fit smoothly into the current interface. But what I'm
currently looking for as a minimum requirement is a way to detect that
the trace was stopped by someone. Then I could live also with the
explicit lttd/lttctl invocations. Do I have to extend the netlink
interface with some wait-on-event service?

Jan

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