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From: Xuewen Yan <xuewen.yan@unisoc.com>
To: <vincent.guittot@linaro.org>, <dietmar.eggemann@arm.com>,
	<mingo@redhat.com>, <peterz@infradead.org>,
	<juri.lelli@redhat.com>, <qyousef@layalina.io>
Cc: <rostedt@goodmis.org>, <bsegall@google.com>, <mgorman@suse.de>,
	<bristot@redhat.com>, <vschneid@redhat.com>,
	<christian.loehle@arm.com>, <vincent.donnefort@arm.com>,
	<ke.wang@unisoc.com>, <di.shen@unisoc.com>,
	<xuewen.yan94@gmail.com>, <linux-kernel@vger.kernel.org>
Subject: [PATCH V2 2/2] sched/fair: Use actual_cpu_capacity everywhere in util_fits_cpu()
Date: Mon, 24 Jun 2024 16:20:11 +0800	[thread overview]
Message-ID: <20240624082011.4990-3-xuewen.yan@unisoc.com> (raw)
In-Reply-To: <20240624082011.4990-1-xuewen.yan@unisoc.com>

Commit f1f8d0a22422 ("sched/cpufreq: Take cpufreq feedback into account")
introduced get_actual_cpu_capacity(), and it had aggregated the
different pressures applied on the capacity of CPUs.
And in util_fits_cpu(), it would return true when uclamp_max
is smaller than SCHED_CAPACITY_SCALE, althought the uclamp_max
is bigger than actual_cpu_capacity.

So use actual_cpu_capacity everywhere in util_fits_cpu() to
cover all cases.

Signed-off-by: Xuewen Yan <xuewen.yan@unisoc.com>
---
 kernel/sched/fair.c | 19 +++++++++----------
 1 file changed, 9 insertions(+), 10 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 5ca6396ef0b7..9c16ae192217 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4980,7 +4980,7 @@ static inline int util_fits_cpu(unsigned long util,
 				int cpu)
 {
 	unsigned long capacity = capacity_of(cpu);
-	unsigned long capacity_orig;
+	unsigned long capacity_actual;
 	bool fits, uclamp_max_fits;
 
 	/*
@@ -4992,15 +4992,15 @@ static inline int util_fits_cpu(unsigned long util,
 		return fits;
 
 	/*
-	 * We must use arch_scale_cpu_capacity() for comparing against uclamp_min and
+	 * We must use actual_cpu_capacity() for comparing against uclamp_min and
 	 * uclamp_max. We only care about capacity pressure (by using
 	 * capacity_of()) for comparing against the real util.
 	 *
 	 * If a task is boosted to 1024 for example, we don't want a tiny
 	 * pressure to skew the check whether it fits a CPU or not.
 	 *
-	 * Similarly if a task is capped to arch_scale_cpu_capacity(little_cpu), it
-	 * should fit a little cpu even if there's some pressure.
+	 * Similarly if a task is capped to actual_cpu_capacity, it should fit
+	 * the cpu even if there's some pressure.
 	 *
 	 * Only exception is for HW or cpufreq pressure since it has a direct impact
 	 * on available OPP of the system.
@@ -5011,7 +5011,7 @@ static inline int util_fits_cpu(unsigned long util,
 	 * For uclamp_max, we can tolerate a drop in performance level as the
 	 * goal is to cap the task. So it's okay if it's getting less.
 	 */
-	capacity_orig = arch_scale_cpu_capacity(cpu);
+	capacity_actual = get_actual_cpu_capacity(cpu);
 
 	/*
 	 * We want to force a task to fit a cpu as implied by uclamp_max.
@@ -5039,7 +5039,7 @@ static inline int util_fits_cpu(unsigned long util,
 	 *     uclamp_max request.
 	 *
 	 *   which is what we're enforcing here. A task always fits if
-	 *   uclamp_max <= capacity_orig. But when uclamp_max > capacity_orig,
+	 *   uclamp_max <= capacity_actual. But when uclamp_max > capacity_actual,
 	 *   the normal upmigration rules should withhold still.
 	 *
 	 *   Only exception is when we are on max capacity, then we need to be
@@ -5050,8 +5050,8 @@ static inline int util_fits_cpu(unsigned long util,
 	 *     2. The system is being saturated when we're operating near
 	 *        max capacity, it doesn't make sense to block overutilized.
 	 */
-	uclamp_max_fits = (capacity_orig == SCHED_CAPACITY_SCALE) && (uclamp_max == SCHED_CAPACITY_SCALE);
-	uclamp_max_fits = !uclamp_max_fits && (uclamp_max <= capacity_orig);
+	uclamp_max_fits = (capacity_actual == SCHED_CAPACITY_SCALE) && (uclamp_max == SCHED_CAPACITY_SCALE);
+	uclamp_max_fits = !uclamp_max_fits && (uclamp_max <= capacity_actual);
 	fits = fits || uclamp_max_fits;
 
 	/*
@@ -5086,8 +5086,7 @@ static inline int util_fits_cpu(unsigned long util,
 	 * handle the case uclamp_min > uclamp_max.
 	 */
 	uclamp_min = min(uclamp_min, uclamp_max);
-	if (fits && (util < uclamp_min) &&
-	    (uclamp_min > get_actual_cpu_capacity(cpu)))
+	if (fits && (util < uclamp_min) && (uclamp_min > capacity_actual))
 		return -1;
 
 	return fits;
-- 
2.25.1


  parent reply	other threads:[~2024-06-24  8:21 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-06-24  8:20 [PATCH V2 0/2] sched/fair: Some improvements to feec() Xuewen Yan
2024-06-24  8:20 ` [PATCH V2 1/2] sched/fair: Prevent cpu_busy_time from exceeding actual_cpu_capacity Xuewen Yan
2024-06-25 13:04   ` Vincent Guittot
2024-06-27  2:02     ` Xuewen Yan
2024-06-27 16:15       ` Vincent Guittot
2024-06-28  1:39         ` Qais Yousef
2024-07-01 12:00         ` Xuewen Yan
2024-07-04 17:01         ` Pierre Gondois
2024-07-05  0:10           ` Qais Yousef
2024-06-24  8:20 ` Xuewen Yan [this message]
2024-06-25  8:46   ` [PATCH V2 2/2] sched/fair: Use actual_cpu_capacity everywhere in util_fits_cpu() Vincent Guittot
2024-06-28  1:28   ` Qais Yousef
2024-07-01 12:13     ` Xuewen Yan
2024-07-03 11:46       ` Qais Yousef
2024-07-02 13:25     ` Vincent Guittot
2024-07-03 11:54       ` Qais Yousef
2024-07-03 14:54         ` Vincent Guittot
2024-07-04 23:56           ` Qais Yousef
2024-07-05  6:25             ` Dietmar Eggemann
2024-07-16 11:56             ` Xuewen Yan

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