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From: Alexander Shishkin <virtuoso@slind.org>
To: Valdis.Kletnieks@vt.edu
Cc: linux-kernel@vger.kernel.org, John Stultz <johnstul@us.ibm.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Kay Sievers <kay.sievers@vrfy.org>, Greg KH <gregkh@suse.de>,
	Chris Friesen <chris.friesen@genband.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	"Kirill A. Shutemov" <kirill@shutemov.name>,
	Thomas Gleixner <tglx@linutronix.de>,
	Alexander Shishkin <virtuoso@slind.org>
Subject: Re: [PATCHv6 0/7] system time changes notification
Date: Thu, 11 Nov 2010 22:51:23 +0200	[thread overview]
Message-ID: <20101111205123.GC10585@shisha.kicks-ass.net> (raw)
In-Reply-To: <22542.1289507293@localhost>

On Thu, Nov 11, 2010 at 03:28:13PM -0500, Valdis.Kletnieks@vt.edu wrote:
> On Thu, 11 Nov 2010 21:29:55 +0200, Alexander Shishkin said:
> 
> > 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.
> 
> Sorry, I tuned in late here...
> 
> So the plan is that if you're not using this new interface, it will go off at
> the same absolute offset (23 hours after timer was set), but if you're using
> this interface, your timer event gets interrupted, you get woken up (say)
> 15 hours into your 23, and it's your job to decide if you need to set a
> new timer for the remaining 6, 7, 8 hours or some other number?

Yes. This interface doesn't deal with timers, it only provides notifications.

Regards,
--
Alex

  reply	other threads:[~2010-11-11 20:51 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-11-11 19:29 Alexander Shishkin
2010-11-11 19:29 ` [PATCHv6 1/7] notify userspace about time changes Alexander Shishkin
2010-11-11 20:55   ` Arnd Bergmann
2010-11-11 19:29 ` [PATCHv6 2/7] wire up sys_time_change_notify() on ARM Alexander Shishkin
2010-11-11 19:29 ` [PATCHv6 3/7] wire up sys_time_change_notify() on x86 Alexander Shishkin
2010-11-11 19:29 ` [PATCHv6 4/7] wire up sys_time_change_notify() on ia64 Alexander Shishkin
2010-11-11 19:30 ` [PATCHv6 5/7] wire up sys_time_change_notify() on s390 Alexander Shishkin
2010-11-11 19:30 ` [PATCHv6 6/7] wire up sys_time_change_notify() on powerpc Alexander Shishkin
2010-11-11 19:30 ` [PATCHv6 7/7] wire up sys_time_change_notify() on blackfin Alexander Shishkin
2010-11-11 20:28 ` [PATCHv6 0/7] system time changes notification Valdis.Kletnieks
2010-11-11 20:51   ` Alexander Shishkin [this message]
2010-11-11 21:16     ` Thomas Gleixner
2010-11-11 22:11       ` Kyle Moffett
2010-11-11 22:36         ` john stultz
2010-11-11 23:19           ` Kyle Moffett
2010-11-11 23:41             ` john stultz
2010-11-11 23:45             ` john stultz
2010-11-11 22:50         ` Thomas Gleixner
2010-11-12  2:35           ` Davide Libenzi
2010-11-17 19:06           ` Alexander Shishkin
2010-11-17 20:42             ` Davide Libenzi
2010-11-17 21:29               ` Alexander Shishkin
2010-11-17 21:34                 ` Kay Sievers
2010-11-18 15:59                   ` Alexander Shishkin
2010-11-17 21:46                 ` Thomas Gleixner
2010-11-18  9:49                   ` Alexander Shishkin
2010-11-18 13:08               ` Artem Bityutskiy
2010-11-12  9:25         ` Alan Cox
2010-11-12 10:53           ` Richard Cochran
2010-11-12 11:25             ` Alan Cox
2010-11-12 10:47       ` Kay Sievers
2010-11-12 12:30       ` Alexander Shishkin

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