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[RFC] Introduce CLOCK_BOOTTIME

From:  John Stultz <john.stultz@linaro.org>
To:  LKML <linux-kernel@vger.kernel.org>
Subject:  [PATCH 0/2] [RFC] Introduce CLOCK_BOOTTIME
Date:  Wed, 15 Dec 2010 16:40:46 -0800
Message-ID:  <1292460048-28035-1-git-send-email-john.stultz@linaro.org>
Cc:  John Stultz <john.stultz@linaro.org>, Jamie Lokier <jamie@shareable.org>, Thomas Gleixner <tglx@linutronix.de>, Alexander Shishkin <virtuoso@slind.org>, =?UTF-8?q?Arve=20Hj=F8nnev=E5g?= <arve@android.com>
Archive-link:  Article

After some discussions with Jamie Lokier about some of the 
drawbacks of CLOCK_MONOTONIC not incrementing during suspend
(see http://www.spinics.net/lists/linux-fsdevel/msg40272.html),
I wanted to see if we couldn't provide a new clockid that would 
allow applications that wanted to be aware of time passing during
suspend without having to deal with the inconsistencies of 
CLOCK_REALTIME caused by calls to settimeofday.

So this patchset introduces CLOCK_BOOTTIME, which is identical
to CLOCK_MONOTONIC, but includes any time spent in suspend.

This is just my initial stab at this, so I'd appreciate any comments
or thougths on these patches.

Jamie: On platforms that don't implement read_persistent_clock,
your issue would still be present, but fixing that is on my list.
Other then that issue, does this seem to address your concern?

Thomas: Let me know if the hrtimer_base indirection is too 
gross. It just seemed silly to create 5 empty bases so we could
have an exact match between the clockids and the bases.

Arve: I believe CLOCK_BOOTTIME would be sufficient for what
Android is using as elapsedRealtime() or 
ANDROID_ALARM_ELAPSED_REALTIME. If not please let me know why.

thanks
-john


CC: Jamie Lokier <jamie@shareable.org>
CC: Thomas Gleixner <tglx@linutronix.de>
CC: Alexander Shishkin <virtuoso@slind.org>
CC: Arve Hj??<arve@android.com>


John Stultz (2):
  hrtimers: extend hrtimer base code to handle more then 2 clockids
  hrtimers: Add CLOCK_BOOTTIME clockid, hrtimerbase and posix interface

 include/linux/hrtimer.h   |   22 ++++++++++++-
 include/linux/time.h      |    4 ++
 kernel/hrtimer.c          |   44 ++++++++++++++++---------
 kernel/posix-timers.c     |   16 ++++++++-
 kernel/time/timekeeping.c |   79 ++++++++++++++++++++++++++++++++++++++++++++-
 5 files changed, 146 insertions(+), 19 deletions(-)

-- 
1.7.3.2.146.gca209

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