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From: Ingo Molnar <mingo@elte.hu>
To: Daniel Walker <dwalker@mvista.com>
Cc: akpm@osdl.org, linux-kernel@vger.kernel.org, johnstul@us.ibm.com,
	Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH 09/23] clocksource: add block notifier
Date: Wed, 31 Jan 2007 11:17:10 +0100	[thread overview]
Message-ID: <20070131101710.GB22377@elte.hu> (raw)
In-Reply-To: <20070131033805.815147778@mvista.com>


* Daniel Walker <dwalker@mvista.com> wrote:

> Adds a call back interface for register/rating change events. This is 
> also used later in this series to signal other interesting events.

This patch adds:

> +#define CLOCKSOURCE_NOTIFY_REGISTER	1
> +#define CLOCKSOURCE_NOTIFY_RATING	2
> +#define CLOCKSOURCE_NOTIFY_FREQ		4

and a later patch adds:

> +#define CLOCKSOURCE_NOTIFY_UNSTABLE	8

while i tentatively agree with the introduction of clocksource driver 
notifications in general (given any actual real users of that 
infrastructure), i can see three problems with your notifier changes:

firstly, with the full changes applied, CLOCKSOURCE_NOTIFY_RATING is 
totally unused (and not even driven by the core clocksource code).

secondly, CLOCKSOURCE_NOTIFY_REGISTER is only used by the core 
clocksource code and no register-notifier interface is exposed: this 
makes the whole thing an expensive NOP.

thirdly, CLOCKSOURCE_NOTIFY_FREQ is totally unused as well.

(there are tons of examples in the kernel of how to do driver 
notification APIs properly.)

	Ingo

  reply	other threads:[~2007-01-31 10:19 UTC|newest]

Thread overview: 57+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-01-31  3:37 [PATCH 00/23] clocksource update v12 Daniel Walker
2007-01-31  3:37 ` [PATCH 01/23] clocksource: drop clocksource-add-verification-watchdog-helper-fix.patch Daniel Walker
2007-01-31 12:47   ` Ingo Molnar
2007-01-31  3:37 ` [PATCH 02/23] clocksource: drop clocksource-add-verification-watchdog-helper.patch Daniel Walker
2007-01-31  3:37 ` [PATCH 03/23] clocksource: drop clocksource-remove-the-update-callback.patch Daniel Walker
2007-01-31  3:37 ` [PATCH 04/23] clocksource: drop time-x86_64-tsc-fixup-clocksource-changes.patch Daniel Walker
2007-01-31  3:37 ` [PATCH 05/23] clocksource: drop simplify-the-registration-of-clocksources.patch Daniel Walker
2007-01-31  3:37 ` [PATCH 06/23] timekeeping: create kernel/time/timekeeping.c Daniel Walker
2007-01-31  8:59   ` Ingo Molnar
2007-01-31 15:05     ` Daniel Walker
2007-01-31  3:37 ` [PATCH 07/23] clocksource: rating sorted list Daniel Walker
2007-01-31  9:34   ` Ingo Molnar
2007-01-31 15:07     ` Daniel Walker
2007-01-31  3:37 ` [PATCH 08/23] clocksource: drop duplicate register checking Daniel Walker
2007-01-31  9:59   ` Ingo Molnar
2007-01-31 15:13     ` Daniel Walker
2007-01-31 17:19       ` Ingo Molnar
2007-01-31  3:37 ` [PATCH 09/23] clocksource: add block notifier Daniel Walker
2007-01-31 10:17   ` Ingo Molnar [this message]
2007-01-31 15:25     ` Daniel Walker
2007-01-31 17:22       ` Ingo Molnar
2007-01-31  3:37 ` [PATCH 10/23] clocksource: remove update_callback Daniel Walker
2007-01-31 10:46   ` Ingo Molnar
2007-01-31 15:42     ` Daniel Walker
2007-01-31 17:18       ` Ingo Molnar
2007-01-31  3:37 ` [PATCH 11/23] clocksource: atomic signals Daniel Walker
2007-01-31 11:07   ` Ingo Molnar
2007-01-31 15:59     ` Daniel Walker
2007-01-31 17:15       ` Ingo Molnar
2007-01-31  3:37 ` [PATCH 12/23] clocksource: add clocksource_get_clock() Daniel Walker
2007-01-31 11:46   ` Ingo Molnar
2007-01-31 16:40     ` Daniel Walker
2007-01-31  3:37 ` [PATCH 13/23] timekeeping: move sysfs layer/drop API calls Daniel Walker
2007-01-31 11:49   ` Ingo Molnar
2007-01-31  3:37 ` [PATCH 14/23] clocksource: increase initcall priority Daniel Walker
2007-01-31 11:50   ` Ingo Molnar
2007-01-31 16:42     ` Daniel Walker
2007-01-31 17:10       ` Ingo Molnar
2007-01-31 17:20         ` Daniel Walker
2007-01-31 17:29           ` Thomas Gleixner
2007-01-31  3:37 ` [PATCH 15/23] clocksource: add new flags Daniel Walker
2007-01-31  3:37 ` [PATCH 16/23] clocksource: arm update for " Daniel Walker
2007-01-31 12:27   ` Ingo Molnar
2007-01-31  3:37 ` [PATCH 17/23] clocksource: avr32 " Daniel Walker
2007-01-31  3:37 ` [PATCH 18/23] clocksource: i386 " Daniel Walker
2007-01-31  3:37 ` [PATCH 19/23] clocksource: mips " Daniel Walker
2007-01-31  3:37 ` [PATCH 20/23] clocksource: x86_64 " Daniel Walker
2007-01-31  3:37 ` [PATCH 21/23] clocksource: drivers/ " Daniel Walker
2007-01-31  3:37 ` [PATCH 22/23] clocksource: new clock lookup method Daniel Walker
     [not found]   ` <20070131122215.GE1847@elte.hu>
     [not found]     ` <1170261439.9781.96.camel@imap.mvista.com>
     [not found]       ` <20070131164918.GA4468@elte.hu>
     [not found]         ` <1170265169.9781.145.camel@imap.mvista.com>
2007-01-31 17:55           ` Thomas Gleixner
2007-01-31 18:07             ` Daniel Walker
2007-01-31 21:09               ` Thomas Gleixner
2007-01-31  3:37 ` [PATCH 23/23] clocksource tsc: add verify routine Daniel Walker
2007-01-31 12:43   ` Ingo Molnar
2007-01-31 17:02     ` Daniel Walker
2007-01-31 17:22       ` Thomas Gleixner
2007-01-31 17:33       ` Ingo Molnar

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