[RFC v2 0/4] tracing: Add support to record and display tgid of tasks

[Joel Fernandes <joelaf@google.com>]

Hi Steven, Ingo,

Here is a rework of the last RFC [1] I posted. Its a a complete rewrite from
scratch to be more upstream friendly.

Android systrace viewer heavily depends on the tgid to group tasks. tgid is
also useful for analyzing traces and generating stats for groups of tasks.

Basically in this approach I try to make sure there is no overhead in terms of
runtime or space usage for existing users who don't need tgid. Only if the
trace option is enabled will the tgid table which does the mapping be allocated
and used.

I tested these and they are showing good results so far, looking forward to
getting your feedback and thoughts on them. Thank you.

[1] https://patchwork.kernel.org/patch/9728283/

Joel Fernandes (4):
  tracing: Remove unused declaration of trace_stop_cmdline_recording
  tracing: Add support for recording tgid of tasks
  tracing: Add support for display of tgid in trace output
  tracing/ftrace: Add support to record and display tgid

 include/linux/trace_events.h         |  10 ++-
 kernel/trace/blktrace.c              |   2 +-
 kernel/trace/trace.c                 | 141 +++++++++++++++++++++++++++--------
 kernel/trace/trace.h                 |   9 ++-
 kernel/trace/trace_events.c          |  84 ++++++++++++++++++---
 kernel/trace/trace_functions.c       |  24 +++++-
 kernel/trace/trace_functions_graph.c |   4 +-
 kernel/trace/trace_output.c          |   9 +++
 kernel/trace/trace_sched_switch.c    |  67 ++++++++++++-----
 kernel/trace/trace_selftest.c        |   2 +-
 10 files changed, 283 insertions(+), 69 deletions(-)

Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: kernel-team@android.com
Signed-off-by: Joel Fernandes <joelaf@google.com>
-- 
2.13.0.506.g27d5fe0cd-goog