| Message ID | 1381775755-8421-5-git-send-email-mohamad.gebai@polymtl.ca |
|---|---|
| State | New |
| Headers | show |
mohamad.gebai@gmail.com writes: > Signed-off-by: Mohamad Gebai <mohamad.gebai@polymtl.ca> > --- > docs/tracing.txt | 31 +++++++++++++++++++++++++++++++ > 1 file changed, 31 insertions(+) > > diff --git a/docs/tracing.txt b/docs/tracing.txt > index bfc261b..64683db 100644 > --- a/docs/tracing.txt > +++ b/docs/tracing.txt > @@ -214,6 +214,37 @@ The "ust" backend uses the LTTng Userspace Tracer library. There are no > monitor commands built into QEMU, instead UST utilities should be used to list, > enable/disable, and dump traces. > > +Package lttng-tools is required for userspace tracing. After running Qemu, LTTng > +should be able to list all available events: > + > + lttng list -u Running this gives me: <quote> UST events: ------------- None </quote> Before or after running qemu. What is the mechanism lttng expects to find out all these events? > + > +Create tracing session: > + > + lttng create mysession > + > +Enable events: > + > + lttng enable-event qemu:g_malloc -u > + > +Where the events can either be a comma-separated list of events, or "-a" to > +enable all tracepoint events. Start and stop tracing as needed: > + > + lttng start > + lttng stop > + > +View the trace: > + > + lttng view > + > +Destroy tracing session: > + > + lttng destroy > + > +Babeltrace can be used at any later time to view the trace: > + > + babeltrace $HOME/lttng-traces/mysession-<date>-<time> > + The rest of this looks OK and worked on my system. > === SystemTap === > > The "dtrace" backend uses DTrace sdt probes but has only been tested with
> Running this gives me: > > <quote> > UST events: > ------------- > None > </quote> > > Before or after running qemu. What is the mechanism lttng expects to > find out all these events? Either the user should belong the group "tracing", or launch the lttng-sessiond daemon (lttng-sessiond -d). > >> + >> +Create tracing session: >> + >> + lttng create mysession >> + >> +Enable events: >> + >> + lttng enable-event qemu:g_malloc -u >> + >> +Where the events can either be a comma-separated list of events, or "-a" to >> +enable all tracepoint events. Start and stop tracing as needed: >> + >> + lttng start >> + lttng stop >> + >> +View the trace: >> + >> + lttng view >> + >> +Destroy tracing session: >> + >> + lttng destroy >> + >> +Babeltrace can be used at any later time to view the trace: >> + >> + babeltrace $HOME/lttng-traces/mysession-<date>-<time> >> + > The rest of this looks OK and worked on my system. > >> === SystemTap === >> >> The "dtrace" backend uses DTrace sdt probes but has only been tested with > Thanks! Mohamad
mohamad.gebai@polymtl.ca writes: >> Running this gives me: >> >> <quote> >> UST events: >> ------------- >> None >> </quote> >> >> Before or after running qemu. What is the mechanism lttng expects to >> find out all these events? > > Either the user should belong the group "tracing", or launch the > lttng-sessiond daemon (lttng-sessiond -d). <snip> Hmm I've done both and I get nothing still. I can enable all tracepoints though. This could just be a Ubuntu weirdness thing though. I'm not sure if mentioning the group/daemon requirements in the tracing doc is required though. I guess these things can be a little package/distro specific?
On 13-10-16 08:05 AM, Alex Bennée wrote: >>> Running this gives me: >>> >>> <quote> >>> UST events: >>> ------------- >>> None >>> </quote> >>> >>> Before or after running qemu. What is the mechanism lttng expects to >>> find out all these events? >> Either the user should belong the group "tracing", or launch the >> lttng-sessiond daemon (lttng-sessiond -d). > <snip> > > Hmm I've done both and I get nothing still. I can enable all tracepoints > though. This could just be a Ubuntu weirdness thing though. That's weird. I did test it on a clean Ubuntu Precise (in a VM) and I didn't have any problem after either one of these steps. Can you please make sure that the user belongs to the "tracing" group and that the lttng-sessiond daemon is running before running any instance of Qemu. Also, Qemu should be running for LTTng to be able to list the events. Does lttng enable-event -a -u/start/stop/view show any event? > > I'm not sure if mentioning the group/daemon requirements in the tracing > doc is required though. I guess these things can be a little > package/distro specific? > > ' This isn't really specific to Ubuntu, it's the setup of LTTng so I guess I could add it to the documentation as well. Thanks! Mohamad
mohamad.gebai@polymtl.ca writes: > On 13-10-16 08:05 AM, Alex Bennée wrote: >>>> Running this gives me: >>>> >>>> <quote> >>>> UST events: >>>> ------------- >>>> None >>>> </quote> >>>> >>>> Before or after running qemu. What is the mechanism lttng expects to >>>> find out all these events? >>> Either the user should belong the group "tracing", or launch the >>> lttng-sessiond daemon (lttng-sessiond -d). >> <snip> >> >> Hmm I've done both and I get nothing still. I can enable all tracepoints >> though. This could just be a Ubuntu weirdness thing though. > > That's weird. I did test it on a clean Ubuntu Precise (in a VM) and I > didn't have any problem after either one of these steps. Can you please > make sure that the user belongs to the "tracing" group and that the > lttng-sessiond daemon is running before running any instance of Qemu. > Also, Qemu should be running for LTTng to be able to list the events. Ahh that was it. I suggest you change the wording from: "Package lttng-tools is required for userspace tracing. After running Qemu, LTTng should be able to list all available events:" to "Package lttng-tools is required for userspace tracing. While running and instrumented Qemu, LTTng should be able to list all available events:" > Does lttng enable-event -a -u/start/stop/view show any event? Yes, as I said the rest worked fine. With that minor wording fix I'm happy. Thanks for getting this back into shape :-)
On 13-10-17 05:20 AM, Alex Bennée wrote: > mohamad.gebai@polymtl.ca writes: > >> On 13-10-16 08:05 AM, Alex Bennée wrote: >>>>> Running this gives me: >>>>> >>>>> <quote> >>>>> UST events: >>>>> ------------- >>>>> None >>>>> </quote> >>>>> >>>>> Before or after running qemu. What is the mechanism lttng expects to >>>>> find out all these events? >>>> Either the user should belong the group "tracing", or launch the >>>> lttng-sessiond daemon (lttng-sessiond -d). >>> <snip> >>> >>> Hmm I've done both and I get nothing still. I can enable all tracepoints >>> though. This could just be a Ubuntu weirdness thing though. >> That's weird. I did test it on a clean Ubuntu Precise (in a VM) and I >> didn't have any problem after either one of these steps. Can you please >> make sure that the user belongs to the "tracing" group and that the >> lttng-sessiond daemon is running before running any instance of Qemu. >> Also, Qemu should be running for LTTng to be able to list the events. > Ahh that was it. I suggest you change the wording from: > > "Package lttng-tools is required for userspace tracing. After running Qemu, LTTng > should be able to list all available events:" > > to > > "Package lttng-tools is required for userspace tracing. While running > and instrumented Qemu, LTTng should be able to list all available events:" Oops! Sorry about that. > >> Does lttng enable-event -a -u/start/stop/view show any event? > Yes, as I said the rest worked fine. With that minor wording fix I'm happy. > > Thanks for getting this back into shape :-) > Happy to do it, I hope it will be useful to others. Mohamad
diff --git a/docs/tracing.txt b/docs/tracing.txt index bfc261b..64683db 100644 --- a/docs/tracing.txt +++ b/docs/tracing.txt @@ -214,6 +214,37 @@ The "ust" backend uses the LTTng Userspace Tracer library. There are no monitor commands built into QEMU, instead UST utilities should be used to list, enable/disable, and dump traces. +Package lttng-tools is required for userspace tracing. After running Qemu, LTTng +should be able to list all available events: + + lttng list -u + +Create tracing session: + + lttng create mysession + +Enable events: + + lttng enable-event qemu:g_malloc -u + +Where the events can either be a comma-separated list of events, or "-a" to +enable all tracepoint events. Start and stop tracing as needed: + + lttng start + lttng stop + +View the trace: + + lttng view + +Destroy tracing session: + + lttng destroy + +Babeltrace can be used at any later time to view the trace: + + babeltrace $HOME/lttng-traces/mysession-<date>-<time> + === SystemTap === The "dtrace" backend uses DTrace sdt probes but has only been tested with
Signed-off-by: Mohamad Gebai <mohamad.gebai@polymtl.ca> --- docs/tracing.txt | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+)