fix_util_avg_jump.patch

From 8fbd03042d00267651bb1f1ce74844ff5b29d9f4 Mon Sep 17 00:00:00 2001
From: Tingjia-0v0 <tjcao980311@gmail.com>
Date: Fri, 10 Apr 2026 14:56:14 -0500
Subject: [PATCH] fix_util_avg_jump

---
 kernel/sched/pelt.h | 29 ++++++++++++++++++++---------
 1 file changed, 20 insertions(+), 9 deletions(-)
diff --git a/kernel/sched/pelt.h b/kernel/sched/pelt.h
index f921302dc40f..0134883b0676 100644
--- a/kernel/sched/pelt.h
+++ b/kernel/sched/pelt.h
@@ -139,20 +139,31 @@ static inline void update_idle_rq_clock_pelt(struct rq *rq)
 {
 	u32 divider = ((LOAD_AVG_MAX - 1024) << SCHED_CAPACITY_SHIFT) - LOAD_AVG_MAX;
 	u32 util_sum = rq->cfs.avg.util_sum;
+	unsigned long compute_ratio;
+	u32 threshold;
+	u64 gap;
 	util_sum += rq->avg_rt.util_sum;
 	util_sum += rq->avg_dl.util_sum;
 
 	/*
-	 * Reflecting stolen time makes sense only if the idle
-	 * phase would be present at max capacity. As soon as the
-	 * utilization of a rq has reached the maximum value, it is
-	 * considered as an always running rq without idle time to
-	 * steal. This potential idle time is considered as lost in
-	 * this case. We keep track of this lost idle time compare to
-	 * rq's clock_task.
+	 * Preserve a proportional part of the clock_task/clock_pelt gap once
+	 * the rq utilization exceeds the amount already implied by the current
+	 * compute ratio. This smooths the lost_idle_time update for partially
+	 * busy rq's while still preserving the full gap at saturation.
 	 */
-	if (util_sum >= divider)
-		rq->lost_idle_time += rq_clock_task(rq) - rq->clock_pelt;
+	compute_ratio = arch_scale_cpu_capacity(cpu_of(rq));
+	compute_ratio = cap_scale(compute_ratio, arch_scale_freq_capacity(cpu_of(rq)));
+	threshold = mult_frac(divider, compute_ratio, SCHED_CAPACITY_SCALE);
+	gap = rq_clock_task(rq) - rq->clock_pelt;
+
+	if (util_sum > threshold && threshold < divider) {
+		u32 preserve_num = min_t(u32, util_sum, divider) - threshold;
+		u32 preserve_den = divider - threshold;
+
+		rq->lost_idle_time += mult_frac(gap, preserve_num, preserve_den);
+	} else if (util_sum >= divider) {
+		rq->lost_idle_time += gap;
+	}
 
 	_update_idle_rq_clock_pelt(rq);
 }
-- 
2.43.0