3  * Timer events oriented CPU idle governor
16  * can be determined at the idle state selection time, although doing that may
18  * for idle state selection.
21  * but even then it is generally unnecessary to consider idle duration values
27  * checks if it can select a shallow idle state using wakeup pattern information
29  * at all.  For this purpose, it counts CPU wakeup events and looks for an idle
30  * state whose target residency has not exceeded the idle duration (measured
37  * idle states provided by the %CPUIdle driver in the ascending order.  That is,
39  * the second idle state (idle state 1), the second bin spans from the target
40  * residency of idle state 1 up to, but not including, the target residency of
41  * idle state 2, the third bin spans from the target residency of idle state 2
42  * up to, but not including, the target residency of idle state 3 and so on.
43  * The last bin spans from the target residency of the deepest idle state
47  * They are updated every time before selecting an idle state for the given CPU
51  * sleep length and the idle duration measured after CPU wakeup fall into the
54  * non-timer wakeup events for which the measured idle duration falls into a bin
55  * that corresponds to an idle state shallower than the one whose bin is fallen
59  * The governor also counts "intercepts" with the measured idle duration below
63  * In order to select an idle state for a CPU, the governor takes the following
67  * 1. Find the deepest enabled CPU idle state (the candidate idle state) and
70  *    - The sum of the "hits" metric for all of the idle states shallower than
74  *    - The sum of the "intercepts" metric for all of the idle states shallower
80  *    a shallower idle state is likely to be more suitable, so look for it.
82  *    - Traverse the enabled idle states shallower than the candidate one in the
86  *      of the idle states between it and the candidate one (including the
90  *      use the given idle state as the new candidate one.
109  * Idle state exit latency threshold used for deciding whether or not to check
134  * @state_bins: Idle state data bins for this CPU.
137  * @short_idles: Wakeups after short idle periods.
193 	 * find the bins that the sleep length and the measured idle duration  in teo_update()
213 	 * If the measured idle duration falls into the same bin as the sleep  in teo_update()
216 	 * the measured idle duration.  in teo_update()
237  * teo_find_shallower_state - Find shallower idle state matching given duration.
240  * @state_idx: Index of the capping idle state.
241  * @duration_ns: Idle duration value to match.
263  * teo_select - Selects the next idle state to enter.
294 	 * be opportunities to ask for a deeper idle state when no imminent  in teo_select()
314 		 * Update the sums of idle state mertics for all of the states  in teo_select()
344 		 * Only one idle state is enabled, so use it, but do not  in teo_select()
352 	 * If the sum of the intercepts metric for all of the idle states  in teo_select()
355 	 * all of the deeper states, a shallower idle state is likely to be a  in teo_select()
362 		 * Look for the deepest idle state whose target residency had  in teo_select()
363 		 * not exceeded the idle duration in over a half of the relevant  in teo_select()
418 	 * idle state shallower than the current candidate one.  in teo_select()
428 	 * are dominant.  Namely, it may effectively prevent deeper idle states  in teo_select()
436 	 * benefit from using a deep idle state in that case would be  in teo_select()
437 	 * questionable anyway for latency reasons.  Thus if the measured idle  in teo_select()
443 	 * shallow idle states regardless of the wakeup type, so the sleep  in teo_select()
479 	 * one or the expected idle duration is shorter than the tick period  in teo_select()