Re: Timekeeping issue on aggressive suspend/resume

From: john stultz
Date: Thu Jun 10 2010 - 15:53:34 EST

On Wed, 2010-06-09 at 23:34 -0700, Suresh Rajashekara wrote:
> On Wed, Jun 9, 2010 at 1:22 PM, Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote:
> > Though we could change that conditionally - the default would still be
> > the freeze of jiffies and CLOCK_MONOTONIC for historical compability.
> If I were to change it only for our implementation, and make all the
> user space timers use CLOCK_REALTIME, then could you please point me
> in a direction as to what part of the kernel I should be touching to
> make that change?

I think Thomas was suggesting that you consider creating a option for
where CLOCK_MONOTONIC included total_sleep_time.

In that case the *hack* (and this is a hack, we'll need some more
thoughtful discussion before anything like it could make it upstream)
would be in timekeeping_resume() to comment out the lines that update
wall_to_monotonic and total_sleep_time.

It would be interesting to hear if that hack works for you, and we can
try to come up with a better way to think about how to accommodate both
views of how to account time over suspend.

Thomas, might this call for a new posix clock_id, CLOCK_BOOTTIME (ie:
CLOCK_MONOTONIC + total_sleep_time) or something that userland could use
to set timers on?


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