Commit 4bd2221f authored by Rafael J. Wysocki's avatar Rafael J. Wysocki
Browse files

cpuidle: governors: teo: Avoid selecting states with zero-size bins 



If the last two enabled idle states have the same target residency which
is at least equal to TICK_NSEC, teo may select the next-to-last one even
though the size of that state's bin is 0, which is confusing.

Prevent that from happening by adding a target residency check to the
relevant code path.

Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: default avatarChristian Loehle <christian.loehle@arm.com>
[ rjw: Fixed a typo in the changelog ]
Link: https://patch.msgid.link/3033265.e9J7NaK4W3@rafael.j.wysocki


Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent 80606f4e

drivers/cpuidle/governors/teo.c

+10 −0
Original line number Diff line number Diff line
@@ -388,6 +388,15 @@ static int teo_select(struct cpuidle_driver *drv, struct cpuidle_device *dev, 
			while (min_idx < idx &&

			       drv->states[min_idx].target_residency_ns < TICK_NSEC)

				min_idx++;



			/*

			 * Avoid selecting a state with a lower index, but with

			 * the same target residency as the current candidate

			 * one.

			 */

			if (drv->states[min_idx].target_residency_ns ==

					drv->states[idx].target_residency_ns)

				goto constraint;

		}



		/*
@@ -410,6 +419,7 @@ static int teo_select(struct cpuidle_driver *drv, struct cpuidle_device *dev, 
		}

	}



constraint:

	/*

	 * If there is a latency constraint, it may be necessary to select an

	 * idle state shallower than the current candidate one.