Commit ef3ef4a0 authored by Mohamad Gebai's avatar Mohamad Gebai Committed by Stefan Hajnoczi
Browse files

Update documentation for LTTng ust tracing 



Signed-off-by: default avatarMohamad Gebai <mohamad.gebai@polymtl.ca>
Reviewed-by: default avatarAlex Bennée <alex.bennee@linaro.org>
Signed-off-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
parent e6bf23f8

docs/tracing.txt

+36 −0
Original line number Diff line number Diff line
@@ -214,6 +214,42 @@ 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. You must ensure that the

current user belongs to the "tracing" group, or manually launch the

lttng-sessiond daemon for the current user prior to running any instance of

QEMU.



While running an instrumented 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