Messages in this thread | | | Date | Tue, 28 Feb 2012 10:19:32 +0400 | From | Dmitry Antipov <> | Subject | Re: [PATCH] sched: generalize CONFIG_IRQ_TIME_ACCOUNTING for X86 and ARM |
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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
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