From: dmitry.antipov@linaro•org (Dmitry Antipov)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH] sched: generalize CONFIG_IRQ_TIME_ACCOUNTING for X86 and ARM
Date: Tue, 28 Feb 2012 10:19:32 +0400 [thread overview]
Message-ID: <4F4C71F4.7000604@linaro.org> (raw)
In-Reply-To: <1330337535.11248.45.camel@twins>
On 02/27/2012 02:12 PM, Peter Zijlstra wrote:
>> -extern void enable_sched_clock_irqtime(void);
>> -extern void disable_sched_clock_irqtime(void);
>> +extern int sched_clock_irqtime;
>> +static inline void enable_sched_clock_irqtime(void)
>> +{
>> + if (sched_clock_irqtime == -1)
>> + sched_clock_irqtime = 1;
>> +}
>> +static inline void disable_sched_clock_irqtime(void)
>> +{
>> + sched_clock_irqtime = 0;
>> +}
>> #else
>> static inline void enable_sched_clock_irqtime(void) {}
>> static inline void disable_sched_clock_irqtime(void) {}
>
> Please keep them out-of-line, its not a fast path and it avoids having
> to expose the state variable.
OK
>> +/*
>> + * -1 if not initialized, 0 if disabled with "noirqtime" kernel option
>> + * or after unstable clock was detected, 1 if enabled and active.
>> + */
>
> You forgot to explain what you need the tri-state for.
>
>> +__read_mostly int sched_clock_irqtime = -1;
The comment above should be a sufficient explanation, isn't it?
It's a tri-state just because it "merges" two variables: internal state (enabled/disabled)
and the value passed by "noirqtime" option (turn it on, default/turn it off). It can be
enabled only if it was not turned off explicitly, i.e. -1 => 1 transition is possible,
but 0 -> 1 is not. The same rule applies to a situation when an unstable clock is detected.
Dmitry
next prev parent reply other threads:[~2012-02-28 6:19 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-20 6:04 [PATCH] sched: generalize CONFIG_IRQ_TIME_ACCOUNTING for X86 and ARM Dmitry Antipov
2012-02-27 10:12 ` Peter Zijlstra
2012-02-28 6:19 ` Dmitry Antipov [this message]
-- strict thread matches above, loose matches on Subject: below --
2012-02-28 6:29 Dmitry Antipov
2012-02-11 0:02 Dmitry Antipov
2012-02-17 11:22 ` Ingo Molnar
2012-02-09 17:25 Dmitry Antipov
2012-02-10 22:28 ` Venki Pallipadi
2012-02-08 23:58 Dmitry Antipov
2012-02-08 16:08 Dmitry Antipov
2012-02-08 22:50 ` Venki Pallipadi
2012-02-08 12:48 Dmitry Antipov
2012-02-08 13:18 ` Russell King - ARM Linux
2012-02-08 15:15 ` Dmitry Antipov
2012-02-08 15:24 ` Russell King - ARM Linux
2012-02-09 2:51 ` Yong Zhang
2012-02-09 2:48 ` Yong Zhang
2012-02-07 18:06 Dmitry Antipov
2012-02-07 22:56 ` Venki Pallipadi
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