* Gerlando Falauto ([email protected]) wrote: > On 10/28/2011 10:24 AM, Mathieu Desnoyers wrote: >> * Gerlando Falauto ([email protected]) wrote: >>> On 10/28/2011 09:39 AM, Mathieu Desnoyers wrote: >>>> * Gerlando Falauto ([email protected]) 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) ;) > > Yeah, it sorta-kinda-most-of-the-times-almost works (R). :-)
:) > > I am having problems seeing those traces on LTTv though. > I had to come up with a workaround by patching LLTv and doing some weird > stuff after loading the trace in order to have LTTv not crash. That's not supposed to be necessary. Which lttv version are you using ? A gdb backtrace of the crash, with lttv compiled with make clean; make CFLAGS=-g would be helpful. > > And also, half the times I cannot see some of the process names (of > course, the ones I am really interested in). Is there any explanation > for this? The flight recording mode does not have the events of the statedump done at the beginning of the trace. You might wait to try saving the statedump-related events into separate channels, which are in "normal" mode (not flight recorder). > >> 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. > > If you don't mind me asking, what's the point of having lttd running in > background in that case (all channels in flight recorder mode)? the metadata channel is always in "normal" mode (not flight recorder), so we need a consumer to get the information as the trace is recorded. Best regards, Mathieu > > Thanks! > Gerlando > -- Mathieu Desnoyers Operating System Efficiency R&D Consultant EfficiOS Inc. http://www.efficios.com _______________________________________________ ltt-dev mailing list [email protected] http://lists.casi.polymtl.ca/cgi-bin/mailman/listinfo/ltt-dev
