Commit f1320a8d authored by K Prateek Nayak's avatar K Prateek Nayak Committed by Peter Zijlstra
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sched/fair: Simplify the entry condition for update_idle_cpu_scan() 



Only the topmost SD_SHARE_LLC domain has the "sd->shared" assigned.
Simply use "sd->shared" as an indicator for load balancing at the highest
SD_SHARE_LLC domain in update_idle_cpu_scan() instead of relying on
llc_size.

Signed-off-by: default avatarK Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: default avatarChen Yu <yu.c.chen@intel.com>
Reviewed-by: default avatarDietmar Eggemann <dietmar.eggemann@arm.com>
Tested-by: default avatarDietmar Eggemann <dietmar.eggemann@arm.com>
Link: https://patch.msgid.link/20260312044434.1974-9-kprateek.nayak@amd.com
parent fa6874df

kernel/sched/fair.c

+4 −6
Original line number Diff line number Diff line
@@ -11234,6 +11234,7 @@ static void update_idle_cpu_scan(struct lb_env *env, 
				 unsigned long sum_util)

{

	struct sched_domain_shared *sd_share;

	struct sched_domain *sd = env->sd;

	int llc_weight, pct;

	u64 x, y, tmp;

	/*
@@ -11247,11 +11248,7 @@ static void update_idle_cpu_scan(struct lb_env *env, 
	if (!sched_feat(SIS_UTIL) || env->idle == CPU_NEWLY_IDLE)

		return;



	llc_weight = per_cpu(sd_llc_size, env->dst_cpu);

	if (env->sd->span_weight != llc_weight)

		return;



	sd_share = rcu_dereference_all(per_cpu(sd_llc_shared, env->dst_cpu));

	sd_share = sd->shared;

	if (!sd_share)

		return;
@@ -11285,10 +11282,11 @@ static void update_idle_cpu_scan(struct lb_env *env, 
	 */

	/* equation [3] */

	x = sum_util;

	llc_weight = sd->span_weight;

	do_div(x, llc_weight);



	/* equation [4] */

	pct = env->sd->imbalance_pct;

	pct = sd->imbalance_pct;

	tmp = x * x * pct * pct;

	do_div(tmp, 10000 * SCHED_CAPACITY_SCALE);

	tmp = min_t(long, tmp, SCHED_CAPACITY_SCALE);