Re: [PATCH] [RFC] notify userspace about time changes

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From: Kay Sievers
Date: Thursday, August 5, 2010 - 4:50 pm

On Fri, Aug 6, 2010 at 00:29, john stultz <johnstul@us.ibm.com> wrote:

That works, yes. The created timer is still is a fixed value, and it
gets automatically adjusted when the system time changes.

This is the example Lennart and I thought about when we considered
adding cron-like stuff to systemd's timer configs, but didn't want to
do silly things like scheduled checks for the actual time, so we
delayed this feature until such a notification becomes available.

Consider we want stuff like "wakeup every day at 3pm", the next wakeup
might be earlier than the timer we calculated last time, on system
time changes. We need to re-calculate it. This is necessary for all
repeating events.

Say we want to wakeup at 3pm, now it's 4pm, so we schedule it in 23
hours. Now the system time changes to 2pm, and we would expect to
wakeup in one hour, but we take 25.

Kay
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Messages in current thread:
[PATCH] [RFC] notify userspace about time changes, Alexander Shishkin, (Wed Aug 4, 5:48 am)
Re: [PATCH] [RFC] notify userspace about time changes, Bastien ROUCARIES, (Wed Aug 4, 5:54 am)
Re: [PATCH] [RFC] notify userspace about time changes, Kirill A. Shutemov, (Wed Aug 4, 8:32 am)
Re: [PATCH] [RFC] notify userspace about time changes, Alexander Shishkin, (Wed Aug 4, 8:46 am)
Re: [PATCH] [RFC] notify userspace about time changes, Alexander Shishkin, (Wed Aug 4, 8:49 am)
Re: [PATCH] [RFC] notify userspace about time changes, Chris Friesen, (Wed Aug 4, 11:48 am)
Re: [PATCH] [RFC] notify userspace about time changes, Kirill A. Shutemov, (Thu Aug 5, 3:05 am)
Re: [PATCH] [RFC] notify userspace about time changes, Alexander Shishkin, (Thu Aug 5, 5:33 am)
Re: [PATCH] [RFC] notify userspace about time changes, Alexander Shishkin, (Thu Aug 5, 5:39 am)
Re: [PATCH] [RFC] notify userspace about time changes, Chris Friesen, (Thu Aug 5, 7:10 am)
Re: [PATCH] [RFC] notify userspace about time changes, H. Peter Anvin, (Thu Aug 5, 3:34 pm)
Re: [PATCH] [RFC] notify userspace about time changes, H. Peter Anvin, (Thu Aug 5, 3:43 pm)
Re: [PATCH] [RFC] notify userspace about time changes, Kay Sievers, (Thu Aug 5, 4:50 pm)
Re: [PATCH] [RFC] notify userspace about time changes, Alexander Shishkin, (Fri Aug 6, 12:11 am)
Re: [PATCH] [RFC] notify userspace about time changes, Alexander Shishkin, (Fri Aug 6, 12:21 am)
Re: [PATCH] [RFC] notify userspace about time changes, Bastien ROUCARIES, (Fri Aug 6, 12:43 am)