On Thu, 2011-06-02 at 15:52 +0800, Yong Zhang wrote: > In sched_clock_local(), clock is calculated around ->tick_gtod even if > that ->tick_gtod is stale for long time because we stays in idle state. > You know ->tick_gtod is only updated in sched_clock_tick(); (well, no, there's idle callbacks as you said below) > IOW, when a cpu goes out of idle, sched_clock_tick() is called from > tick_nohz_stop_idle() which is later than interrupt. Gah, that would be awefull and mean wakeups from interrupts were already borken. /me goes look at code. irq_enter() -> tick_check_idle() -> tick_check_nohz() -> tick_nohz_stop_idle() -> sched_clock_idle_wakeup_event() should update the thing before we run any isrs, right? > So if we have any site which call sched_clock() in interrupt on an > idle cpu, it could get incorrect clock. > > I'm not sure how to teach sched_clock() about this special case, Peter? isn't anything to teach afaict. -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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