Len Brown b73026b9c9 cpuidle: ladder: Better idle duration measurement without using CPUIDLE_FLAG_TIME_INVALID ... When the ladder governor sees the CPUIDLE_FLAG_TIME_INVALID flag, it unconditionally causes a state promotion by setting last_residency to a number higher than the state's promotion_time: last_residency = last_state->threshold.promotion_time + 1 It does this for fear that cpuidle_get_last_residency() will be in-accurate, because cpuidle_enter_state() invoked a state with CPUIDLE_FLAG_TIME_INVALID. But the only state with CPUIDLE_FLAG_TIME_INVALID is acpi_safe_halt(), which may return well after its actual idle duration because it enables interrupts, so cpuidle_enter_state() also measures interrupt service time. So what? In ladder, a huge invalid last_residency has exactly the same effect as the current code -- it unconditionally causes a state promotion. In the case where the idle residency plus measured interrupt handling time is less than the state's demotion_time -- we should use that timestamp to give ladder a chance to demote, rather than unconditionally promoting. This can be done by simply ignoring the CPUIDLE_FLAG_TIME_INVALID, and using the "invalid" time, as it is either equal to what we are doing today, or better. Signed-off-by: Len Brown <len.brown@intel.com> Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>		2014-12-17 02:26:28 +01:00
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ladder.c	cpuidle: ladder: Better idle duration measurement without using CPUIDLE_FLAG_TIME_INVALID	2014-12-17 02:26:28 +01:00
Makefile
menu.c	cpuidle: menu: Better idle duration measurement without using CPUIDLE_FLAG_TIME_INVALID	2014-12-17 02:26:28 +01:00