[PATCH v3 0/3] timekeeping: Introduce a fast boot clock derived from fast monotonic clock

[Joel Fernandes <joelaf@google.com>]

Currently no trace clock can account for suspend time, using monotonic during
tracing in the suspend path means the trace times wont be advaced. Using the
boot clock with ktime_get_with_offset is not an option due to live locking
concerns in NMI context as suggested by Thomas [1].

These patches add a fast boot clock based on fast monotonic clock and adds a
trace clock based on it. Instead of bloating the optimal case [2], these
patches present a simple approach.  Thanks Thomas for making documentation
suggestions for effects of this approach [3].

[1] https://lkml.org/lkml/2016/11/20/75
[2] https://www.spinics.net/lists/kernel/msg2389485.html
[3] https://lkml.org/lkml/2016/11/23/166

Joel Fernandes (3):
  timekeeping: Add a fast and NMI safe boot clock
  trace: Add an option for boot clock as trace clock
  trace: Update documentation for mono, mono_raw and boot clock

 Documentation/trace/ftrace.txt | 20 ++++++++++++++++++++
 include/linux/timekeeping.h    |  1 +
 kernel/time/timekeeping.c      | 28 ++++++++++++++++++++++++++++
 kernel/trace/trace.c           |  1 +
 4 files changed, 50 insertions(+)

Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Ingo Molnar <mingo@redhat.com>
-- 
2.8.0.rc3.226.g39d4020