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From: Ingo Molnar <mingo@elte.hu>
To: Ulrich Windl <ulrich.windl@rz.uni-regensburg.de>
Cc: Roman Zippel <zippel@linux-m68k.org>,
	john stultz <johnstul@us.ibm.com>,
	lkml <linux-kernel@vger.kernel.org>,
	Darren Hart <dvhltc@us.ibm.com>,
	Nishanth Aravamudan <nacc@us.ibm.com>,
	Frank Sorenson <frank@tuxrocks.com>,
	Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH 2/13] Time: Reduced NTP Rework (part 2)
Date: Tue, 6 Dec 2005 08:27:08 +0100	[thread overview]
Message-ID: <20051206072708.GA25129@elte.hu> (raw)
In-Reply-To: <4395475C.21877.29399CFE@Ulrich.Windl.rkdvmks1.ngate.uni-regensburg.de>


* Ulrich Windl <ulrich.windl@rz.uni-regensburg.de> wrote:

> > I'm thinking about moving the leap second handling to a timer, with the 
> > new timer system it would be easy to set a timer for e.g. 23:59.59 and 
> > then set the time. This way it would be gone from the common path and it 
> > wouldn't matter that much anymore whether it's used or not.
> 
> Will the timer solution guarantee consistent and exact updates?

it would still be dependent on system-load situations. It's an 
interesting idea to use a timer for that, but there is no strict 
synchronization between "get time of day" and "timer execution", so any 
timer-based leap-second handling would be fundamentally asynchronous. I 
dont think we want that, leap second handling should be a synchronous 
property of 'time'.

i think the very first step should be the cleanups i did to the NTP 
portions of timer.c. That made all the code (including leap second 
handling) more readable. I think a portion of the inner desire to 
rewrite the NTP code comes from the current spaghetti that accumulated 
over the years.

	Ingo

  reply	other threads:[~2005-12-06  7:27 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-12-02  3:25 [PATCH 0/13] Time: Generic Timeofday Subsystem (v B12) john stultz
2005-12-02  3:25 ` [PATCH 1/13] Time: Reduced NTP rework (part 1) john stultz
2005-12-02  3:26 ` [PATCH 2/13] Time: Reduced NTP Rework (part 2) john stultz
2005-12-03  0:19   ` George Anzinger
2005-12-03  0:35     ` john stultz
2005-12-05  7:59     ` Ulrich Windl
2005-12-06 20:26       ` George Anzinger
2005-12-07  7:33         ` Ulrich Windl
2005-12-05 10:35     ` Roman Zippel
2005-12-06  7:10       ` Ulrich Windl
2005-12-06  7:27         ` Ingo Molnar [this message]
2005-12-06 10:35           ` Roman Zippel
2005-12-06 10:50             ` Ingo Molnar
2005-12-07  7:23             ` Ulrich Windl
2005-12-02  3:26 ` [PATCH 3/13] Time: Clocksource Infrastructure john stultz
2005-12-02  3:26 ` [PATCH 4/13] Time: Generic Timekeeping Infrastructure john stultz
2005-12-02  3:26 ` [PATCH 5/13] Time: i386 Conversion - part 1: Move timer_pit.c to i8253.c john stultz
2005-12-02  3:26 ` [PATCH 6/13] Time: i386 Conversion - part 2: Move timer_tsc.c to tsc.c john stultz
2005-12-02  3:26 ` [PATCH 7/13] Time: i386 Conversion - part 3: Rework TSC Support john stultz
2005-12-02  3:26 ` [PATCH 8/13] Time: i386 Conversion - part 4: ACPI PM variable renaming john stultz
2005-12-02  3:26 ` [PATCH 9/13] Time: i386 Conversion - part 5: Enable Generic Timekeeping john stultz
2005-12-02  3:27 ` [PATCH 10/13] Time: i386 Conversion - part 6: Remove Old Code john stultz
2005-12-02  3:27 ` [PATCH 11/13] Time: i386/x86-64 Clocksource Drivers john stultz
2005-12-02  3:27 ` [PATCH 12/13] Time: x86-64 Conversion to Generic Timekeeping john stultz
2005-12-02  3:27 ` [PATCH 13/13] Time: Generic Timekeeping Paraniod Debug Patch john stultz
  -- strict thread matches above, loose matches on Subject: below --
2005-12-15  2:00 [PATCH 0/13] Time: Generic Timeofday Subsystem (v B14) john stultz
2005-12-15  2:00 ` [PATCH 2/13] Time: Reduced NTP Rework (part 2) john stultz
2005-12-06  4:13 [PATCH 0/13] Time: Generic Timeofday Subsystem (v B13) john stultz
2005-12-06  4:14 ` [PATCH 2/13] Time: Reduced NTP Rework (part 2) john stultz
2005-11-22  1:35 [PATCH 0/13] Time: Generic Timeofday Subsystem (v B11) john stultz
2005-11-22  1:35 ` [PATCH 2/13] Time: Reduced NTP Rework (part 2) john stultz
2005-11-26 14:53   ` Ingo Molnar
2005-11-12  4:48 [PATCH 0/13] Time: Generic Timeofday Subsystem (v B10) john stultz
2005-11-12  4:49 ` [PATCH 2/13] Time: Reduced NTP Rework (part 2) john stultz

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