19 Sep, 2011

1 commit

• 6249687f7   tracing: Add a counter clock for those that do not trust clocks ... Browse Code »

  When debugging tight race conditions, it can be helpful to have a
  synchronized tracing method. Although in most cases the global clock
  provides this functionality, if timings is not the issue, it is more
  comforting to know that the order of events really happened in a precise
  order.

  Instead of using a clock, add a "counter" that is simply an incrementing
  atomic 64bit counter that orders the events as they are perceived to
  happen.

  The trace_clock_counter() is added from the attempt by Peter Zijlstra
  trying to convert the trace_clock_global() to it. I took Peter's counter
  code and made trace_clock_counter() instead, and added it to the choice
  of clocks. Just echo counter > /debug/tracing/trace_clock to activate
  it.

  Requested-by: Thomas Gleixner
  Requested-by: Peter Zijlstra
  Reviewed-By: Valdis Kletnieks
  Signed-off-by: Steven Rostedt

  Steven Rostedt

  2011-09-19 23:35:58 +0800  

27 Feb, 2009

1 commit

• 14131f2f9   tracing: implement trace_clock_*() APIs ... Browse Code »

  Impact: implement new tracing timestamp APIs

  Add three trace clock variants, with differing scalability/precision
  tradeoffs:

  - local: CPU-local trace clock
  - medium: scalable global clock with some jitter
  - global: globally monotonic, serialized clock

  Make the ring-buffer use the local trace clock internally.

  Acked-by: Peter Zijlstra
  Acked-by: Steven Rostedt
  Signed-off-by: Ingo Molnar

  Ingo Molnar

  2009-02-27 01:44:06 +0800