Re: [PATCHv3 linux-next] hrtimer: Add notifier when clock_was_setwas called

From: Thomas Gleixner
Date: Fri Sep 13 2013 - 10:33:09 EST


On Fri, 13 Sep 2013, Fan Du wrote:
> (2) What I have been bugging you around here for this long time is really the
> second
> problem, I'm sorry I didn't make it clearly to you and others, which is
> below:
>
> Why using wall clock time to calculate soft/hard IPsec events when
> xfrm_state timer
> out happens in its timeout handler? Because even if xfrm_state using
> CLOCK_BOOTTIME,
> system wall clock time changing will surely disturb soft/hard IPsec
> events, which
> you raised your concern about in (*a*).

No CLOCK_BOOTTIME is not affected by wall clock time changes. It's
basically CLOCK_MONOTONIC, it just keeps counting the suspend time as
well. So without a suspend/resume cycle CLOCK_MONOTONIC and
CLOCK_BOOTTIME are the same. After a suspend/resume cycle
CLOCK_BOOTTIME will be N seconds ahead of CLOCK_MONOTONIC, where N is
the number of seconds spent in suspend.

Thanks,

tglx
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