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From: Stephen Boyd <sboyd@codeaurora.org>
To: John Stultz <john.stultz@linaro.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Cc: Dave Jones <davej@codemonkey.org.uk>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Richard Cochran <richardcochran@gmail.com>,
	Prarit Bhargava <prarit@redhat.com>,
	Ingo Molnar <mingo@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH 02/10] clocksource: Simplify logic around clocksource wrapping saftey margins
Date: Fri, 09 Jan 2015 18:03:34 -0800	[thread overview]
Message-ID: <54B08876.1040200@codeaurora.org> (raw)
In-Reply-To: <1420850068-27828-3-git-send-email-john.stultz@linaro.org>

On 01/09/2015 04:34 PM, John Stultz wrote:
> The clocksource logic has a number of places where we try to
> include a safety margin. Most of these are 12% safety margins,
> but they are inconsistently applied and sometimes are applied
> on top of each other.
>
> Additionally, in the previous patch, we corrected an issue
> where we unintentionally in effect created a 50% saftey margin,
> which these 12.5% margins where then added to.
>
> So to siplify the logic here, this patch removes the various
> 12.5% margins, and consolidates adding the margin in one place:
> clocks_calc_max_nsecs().
>
> Addtionally, Linus prefers a 50% safety margin, as it allows
> bad clock values to be more easily caught. This should really
> have no net effect, due to the corrected issue earlier which
> caused greater then 50% margins to be used w/o issue.
>
> Cc: Dave Jones <davej@codemonkey.org.uk>
> Cc: Linus Torvalds <torvalds@linux-foundation.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Richard Cochran <richardcochran@gmail.com>
> Cc: Prarit Bhargava <prarit@redhat.com>
> Cc: Stephen Boyd <sboyd@codeaurora.org>
> Cc: Ingo Molnar <mingo@kernel.org>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Signed-off-by: John Stultz <john.stultz@linaro.org>
> ---

For sched_clock.c part

Acked-by: Stephen Boyd <sboyd@codeaurora.org>

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project


  reply	other threads:[~2015-01-10  2:03 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-01-10  0:34 [PATCH 00/10][RFC] Increased clocksource validation and cleanups John Stultz
2015-01-10  0:34 ` [PATCH 01/10] clocksource: Simplify clocks_calc_max_nsecs logic John Stultz
2015-01-10  0:34 ` [PATCH 02/10] clocksource: Simplify logic around clocksource wrapping saftey margins John Stultz
2015-01-10  2:03   ` Stephen Boyd [this message]
2015-01-10  0:34 ` [PATCH 03/10] clocksource: Remove clocksource_max_deferment() John Stultz
2015-01-11 11:47   ` Richard Cochran
2015-01-12 18:36     ` John Stultz
2015-01-12 20:16       ` Richard Cochran
2015-01-10  0:34 ` [PATCH 04/10] clocksource: Add max_cycles to clocksource structure John Stultz
2015-01-10  2:06   ` Stephen Boyd
2015-01-10  0:34 ` [PATCH 05/10] time: Add debugging checks to warn if we see delays John Stultz
2015-01-10  0:34 ` [PATCH 06/10] time: Cap clocksource reads to the clocksource max_cycles value John Stultz
2015-01-11 12:41   ` Richard Cochran
2015-01-12 18:54     ` John Stultz
2015-01-12 19:02       ` Linus Torvalds
2015-01-12 20:37         ` Richard Cochran
2015-01-12 20:30       ` Richard Cochran
2015-01-12 20:49         ` Richard Cochran
2015-01-13 11:11   ` Peter Zijlstra
2015-01-13 21:33     ` John Stultz
2015-01-13 22:51       ` Linus Torvalds
2015-01-14  9:35       ` Peter Zijlstra
2015-01-22 20:55         ` John Stultz
2015-01-10  0:34 ` [PATCH 07/10] time: Try to catch clocksource delta underflows John Stultz
2015-01-10  0:34 ` [PATCH 08/10] clocksource: Mostly kill clocksource_register() John Stultz
2015-01-10  0:34 ` [PATCH 09/10] sparc: Convert to using clocksource_register_hz() John Stultz
2015-01-10  0:34 ` [PATCH 10/10] clocksource: Add some debug info about clocksources being registered John Stultz
2015-01-10  2:02   ` Stephen Boyd
2015-01-22  0:51     ` John Stultz
2015-01-22 12:27       ` Prarit Bhargava
2015-01-11 11:41 ` [PATCH 00/10][RFC] Increased clocksource validation and cleanups Richard Cochran
2015-01-12 18:22   ` John Stultz
2015-01-12 20:45     ` Richard Cochran

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