All events from 'perf list', except SDT events, can be directly recorded
with 'perf record'. But, the flow is little different for SDT events.
Probe points for SDT event needs to be created using 'perf probe' before
recording it using 'perf record'.
Perf shows misleading hint when a user tries to record SDT event without
first creating a probe point. Show proper hint there.
Before patch:
$ perf record -a -e sdt_glib:idle__add
event syntax error: 'sdt_glib:idle__add'
\___ unknown tracepoint
Error: File /sys/kernel/debug/tracing/events/sdt_glib/idle__add not found.
Hint: Perhaps this kernel misses some CONFIG_ setting to enable this feature?.
...
After patch:
$ perf record -a -e sdt_glib:idle__add
event syntax error: 'sdt_glib:idle__add'
\___ unknown tracepoint
Error: File /sys/kernel/debug/tracing/events/sdt_glib/idle__add not found.
Hint: SDT event cannot be directly recorded on.
Please first use 'perf probe sdt_glib:idle__add' before recording it.
...
$ perf probe sdt_glib:idle__add
Added new event:
sdt_glib:idle__add (on %idle__add in /usr/lib64/libglib-2.0.so.0.5000.2)
You can now use it in all perf tools, such as:
perf record -e sdt_glib:idle__add -aR sleep 1
$ perf record -a -e sdt_glib:idle__add
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.175 MB perf.data ]
Suggested-and-Acked-by: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexis Berlemont <alexis.berlemont@gmail.com>
Cc: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20170203102642.17258-1-ravi.bangoria@linux.vnet.ibm.com
[ s/Please use/Please first use/ and break the Hint line in two ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Storing the actual tracing path mountpoint to display correct
error message hint ('Hint:' line). The error hint rediscovers
mountpoints, but it could be different from what we actually
used in tracing path.
Before we'd display debugfs mount even though tracefs was used:
$ perf record -e sched:sched_krava ls
event syntax error: 'sched:sched_krava'
\___ can't access trace events
Error: No permissions to read /sys/kernel/debug/tracing/events/sched/sched_krava
Hint: Try 'sudo mount -o remount,mode=755 /sys/kernel/debug'
...
After this change, correct mountpoint is displayed:
$ perf record -e sched:sched_krava ls
event syntax error: 'sched:sched_krava'
\___ can't access trace events
Error: No permissions to read /sys/kernel/debug/tracing/events/sched/sched_krava
Hint: Try 'sudo mount -o remount,mode=755 /sys/kernel/debug/tracing'
...
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Raphael Beamonte <raphael.beamonte@gmail.com>
Link: http://lkml.kernel.org/r/1442674027-19427-1-git-send-email-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
