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From: "Rafael J. Wysocki" <rjw@rjwysocki.net>
To: Linux PM <linux-pm@vger.kernel.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Daniel Lezcano <daniel.lezcano@linaro.org>,
	Christian Loehle <christian.loehle@arm.com>,
	Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Subject: [PATCH v1 2/4] cpuidle: teo: Rearrange idle state lookup code
Date: Fri, 10 Jan 2025 13:54:39 +0100	[thread overview]
Message-ID: <3332506.aeNJFYEL58@rjwysocki.net> (raw)
In-Reply-To: <4953183.GXAFRqVoOG@rjwysocki.net>

From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Rearrange code in the idle state lookup loop in teo_select() to make it
somewhat easier to follow and update comments around it.

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
 drivers/cpuidle/governors/teo.c |   34 ++++++++++++++++++++--------------
 1 file changed, 20 insertions(+), 14 deletions(-)

--- a/drivers/cpuidle/governors/teo.c
+++ b/drivers/cpuidle/governors/teo.c
@@ -367,7 +367,7 @@
 	 * If the sum of the intercepts metric for all of the idle states
 	 * shallower than the current candidate one (idx) is greater than the
 	 * sum of the intercepts and hits metrics for the candidate state and
-	 * all of the deeper states a shallower idle state is likely to be a
+	 * all of the deeper states, a shallower idle state is likely to be a
 	 * better choice.
 	 */
 	prev_intercept_idx = idx;
@@ -396,30 +396,36 @@
 				 * first enabled state that is deep enough.
 				 */
 				if (teo_state_ok(i, drv) &&
-				    !dev->states_usage[i].disable)
+				    !dev->states_usage[i].disable) {
 					idx = i;
-				else
-					idx = first_suitable_idx;
-
+					break;
+				}
+				idx = first_suitable_idx;
 				break;
 			}
 
 			if (dev->states_usage[i].disable)
 				continue;
 
-			if (!teo_state_ok(i, drv)) {
+			if (teo_state_ok(i, drv)) {
 				/*
-				 * The current state is too shallow, but if an
-				 * alternative candidate state has been found,
-				 * it may still turn out to be a better choice.
+				 * The current state is deep enough, but still
+				 * there may be a better one.
 				 */
-				if (first_suitable_idx != idx)
-					continue;
-
-				break;
+				first_suitable_idx = i;
+				continue;
 			}
 
-			first_suitable_idx = i;
+			/*
+			 * The current state is too shallow, so if no suitable
+			 * states other than the initial candidate have been
+			 * found, give up (the remaining states to check are
+			 * shallower still), but otherwise the first suitable
+			 * state other than the initial candidate may turn out
+			 * to be preferable.
+			 */
+			if (first_suitable_idx == idx)
+				break;
 		}
 	}
 	if (!idx && prev_intercept_idx &&




  parent reply	other threads:[~2025-01-10 12:57 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-01-10 12:51 [PATCH v1 0/4] cpuidle: teo: Fix and cleanups Rafael J. Wysocki
2025-01-10 12:53 ` [PATCH v1 1/4] cpuidle: teo: Add polling flag check to early return path Rafael J. Wysocki
2025-01-10 13:16   ` Christian Loehle
2025-01-10 13:34     ` Rafael J. Wysocki
2025-01-10 14:52       ` Christian Loehle
2025-01-10 15:17         ` Rafael J. Wysocki
2025-01-10 17:23         ` Rafael J. Wysocki
2025-01-23 16:54     ` Artem Bityutskiy
2025-01-23 18:12       ` Rafael J. Wysocki
2025-01-10 12:54 ` Rafael J. Wysocki [this message]
2025-01-10 12:55 ` [PATCH v1 3/4] cpuidle: teo: Reorder candidate state index checks Rafael J. Wysocki
2025-01-10 12:56 ` [PATCH v1 4/4] cpuidle: teo: Combine candidate state index checks against 0 Rafael J. Wysocki

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