perf timechart: Generate backtrace only if needed

The backtrace was used by sched-switch and sched-wakeup only.  No need
to call cat_backtrace() in the process_sample_event().  Let's pass NULL
backtrace and generate it from the sched events.

As it needs a pointer to the 'machine', let's save the session in the
timechart struct and use the host machine of the session instead of
passing the pointer to all handlers.  It should be fine to assume the
host machine as timechart command doesn't deal with guest machines and
there's no way to get tracepoints from the guest events.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>

0 files changed, 0 insertions, 0 deletions