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

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Message-Id: <1480018851-3796-1-git-send-email-joelaf@google.com>
Date:   Thu, 24 Nov 2016 12:20:48 -0800
From:   Joel Fernandes <joelaf@...gle.com>
To:     linux-kernel@...r.kernel.org
Cc:     Joel Fernandes <joelaf@...gle.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        John Stultz <john.stultz@...aro.org>,
        Ingo Molnar <mingo@...hat.com>
Subject: [PATCH v3 0/3] timekeeping: Introduce a fast boot clock derived from fast monotonic clock

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@...dmis.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: John Stultz <john.stultz@...aro.org>
Cc: Ingo Molnar <mingo@...hat.com>
-- 
2.8.0.rc3.226.g39d4020