linux-kernel - Re: [PATCH 0/2] Introduce a fast boot clock and add it as trace clock

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Message-ID: <CAJWu+opEHKBm-4PzdBHTAy6CmgPvrOqFoGB00CTMTKjaHN3khw@mail.gmail.com>
Date:   Mon, 21 Nov 2016 14:06:50 -0800
From:   Joel Fernandes <joelaf@...gle.com>
To:     LKML <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: Re: [PATCH 0/2] Introduce a fast boot clock and add it as trace clock

On Mon, Nov 21, 2016 at 2:04 PM, Joel Fernandes <joelaf@...gle.com> wrote:
> 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 which solves both these issues.
>
> Changes since RFC:
> - Moved the ktime_t offsets to the end of tk_fast
> - use unlikely to optimize for the monotonic case
>

Please scratch these patches, I didn't make a change I had to since
the RFC. Sorry for the noise!

> [1] https://lkml.org/lkml/2016/11/20/75
>
> Joel Fernandes (2):
>   timekeeping: Introduce a fast boot clock derived from fast monotonic
>     clock
>   trace: Add an option for boot clock as trace clock
>
>  kernel/time/timekeeping.c | 36 ++++++++++++++++++++++++++++++------
>  kernel/trace/trace.c      |  1 +
>  2 files changed, 31 insertions(+), 6 deletions(-)
>
> 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
>