From: Will Deacon <will.deacon@arm.com>
To: Stephen Boyd <sboyd@codeaurora.org>
Cc: John Stultz <john.stultz@linaro.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-arm-msm@vger.kernel.org" <linux-arm-msm@vger.kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Russell King <linux@arm.linux.org.uk>,
Catalin Marinas <Catalin.Marinas@arm.com>,
Christopher Covington <cov@codeaurora.org>
Subject: Re: [PATCH v4 02/17] sched_clock: Use seqcount instead of rolling our own
Date: Fri, 19 Jul 2013 10:03:28 +0100 [thread overview]
Message-ID: <20130719090328.GA18139@mudshark.cambridge.arm.com> (raw)
In-Reply-To: <1374189690-10810-3-git-send-email-sboyd@codeaurora.org>
On Fri, Jul 19, 2013 at 12:21:15AM +0100, Stephen Boyd wrote:
> We're going to increase the cyc value to 64 bits in the near
> future. Doing that is going to break the custom seqcount
> implementation in the sched_clock code because 64 bit numbers
> aren't guaranteed to be atomic. Replace the cyc_copy with a
> seqcount to avoid this problem.
>
> Cc: Russell King <linux@arm.linux.org.uk>
> Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
> ---
> kernel/time/sched_clock.c | 27 ++++++++-------------------
> 1 file changed, 8 insertions(+), 19 deletions(-)
Looks good to me. The current scheme would be very fiddly to extend to
64-bit values on 32-bit architectures without cheap atomic doubleword
accesses.
Acked-by: Will Deacon <will.deacon@arm.com>
Will
next prev parent reply other threads:[~2013-07-19 9:04 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-07-18 23:21 [PATCH v4 00/17] 64-bit friendly generic sched_clock() Stephen Boyd
2013-07-18 23:21 ` [PATCH v4 01/17] clocksource: Extract max nsec calculation into separate function Stephen Boyd
2013-07-18 23:21 ` [PATCH v4 02/17] sched_clock: Use seqcount instead of rolling our own Stephen Boyd
2013-07-19 9:03 ` Will Deacon [this message]
2013-07-19 14:20 ` Nicolas Pitre
2013-07-19 14:27 ` Russell King - ARM Linux
2013-07-18 23:21 ` [PATCH v4 03/17] sched_clock: Use an hrtimer instead of timer Stephen Boyd
2013-07-22 18:21 ` John Stultz
2013-07-22 18:45 ` Stephen Boyd
2013-07-22 18:58 ` Stephen Boyd
2013-07-22 19:07 ` Russell King - ARM Linux
2013-07-22 20:48 ` John Stultz
2013-07-22 20:50 ` Stephen Boyd
2013-07-18 23:21 ` [PATCH v4 04/17] sched_clock: Add support for >32 bit sched_clock Stephen Boyd
2013-07-19 9:23 ` Baruch Siach
2013-07-19 16:29 ` Stephen Boyd
2013-07-18 23:21 ` [PATCH v4 05/17] arch_timer: Move to generic sched_clock framework Stephen Boyd
2013-10-02 17:44 ` Will Deacon
2013-10-14 18:44 ` Kevin Hilman
2013-10-14 18:55 ` Stephen Boyd
2013-10-14 20:14 ` Kevin Hilman
2013-10-14 20:18 ` John Stultz
2013-10-14 20:14 ` John Stultz
2013-07-18 23:21 ` [PATCH v4 06/17] sched_clock: Remove sched_clock_func() hook Stephen Boyd
2013-07-18 23:21 ` [PATCH v4 07/17] clocksource: bcm2835: Switch to sched_clock_register() Stephen Boyd
2013-07-19 19:34 ` Stephen Warren
2013-07-30 10:04 ` Daniel Lezcano
2013-07-30 16:12 ` John Stultz
2013-07-18 23:21 ` [PATCH v4 08/17] ocksource: dbx500-prcmu: " Stephen Boyd
2013-07-19 0:18 ` Stephen Boyd
2013-07-18 23:21 ` [PATCH v4 09/17] clocksource: dw_apb_timer_of: " Stephen Boyd
2013-07-18 23:21 ` [PATCH v4 10/17] clocksource: mxs_timer: " Stephen Boyd
2013-07-22 8:10 ` Shawn Guo
2013-07-22 16:23 ` Stephen Boyd
2013-07-18 23:21 ` [PATCH v4 11/17] clocksource: nomadik: " Stephen Boyd
2013-07-18 23:21 ` [PATCH v4 12/17] clocksource: samsung_pwm_timer: " Stephen Boyd
2013-07-18 23:21 ` [PATCH v4 13/17] clocksource: tegra: " Stephen Boyd
2013-07-19 19:34 ` Stephen Warren
2013-07-18 23:21 ` [PATCH v4 14/17] clocksource: time-armada-370-xp: " Stephen Boyd
2013-08-06 9:04 ` Gregory CLEMENT
2013-07-18 23:21 ` [PATCH v4 15/17] clocksource: sirf: Switch to sched_clock_register() and use 64 bits Stephen Boyd
2013-07-18 23:21 ` [PATCH v4 16/17] clocksource: vf_pit_timer: Switch to sched_clock_register() Stephen Boyd
2013-07-18 23:21 ` [PATCH v4 17/17] sched_clock: Deprecate setup_sched_clock() Stephen Boyd
2013-07-18 23:59 ` [PATCH v4 00/17] 64-bit friendly generic sched_clock() John Stultz
2013-07-19 0:23 ` Stephen Boyd
2013-10-02 17:47 ` Will Deacon
2013-10-02 18:02 ` John Stultz
2013-10-02 18:13 ` Will Deacon
2013-07-20 20:51 ` Linus Walleij
2013-07-22 16:24 ` Stephen Boyd
2013-07-22 17:07 ` John Stultz
2013-07-24 14:44 ` Christopher Covington
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