ANDROID: sched: Enable idle balance to pull single task towards cpu with higher capacity (b5234031) · Commits · e / devices / android_kernel_oneplus_sm8150

We do not want to miss out on the ability to pull a single remaining task from a potential source cpu towards an idle destination cpu. Add an extra criteria to need_active_balance() to kick off active load balance if the source cpu is over-utilized and has lower capacity than the destination cpu. cc: Ingo Molnar <mingo@redhat.com> cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by:

Morten Rasmussen <morten.rasmussen@arm.com> Signed-off-by:

Dietmar Eggemann <dietmar.eggemann@arm.com> Change-Id: Ifa66a30d53c17d339fc5058901a87a643ffc3704 Signed-off-by:

Chris Redpath <chris.redpath@arm.com>

kernel/sched/fair.c

+12 −0

Original line number	Diff line number	Diff line
		@@ -5925,6 +5925,11 @@ static int wake_cap(struct task_struct *p, int cpu, int prev_cpu)
		return min_cap * 1024 < task_util(p) * capacity_margin;
		}

		static bool cpu_overutilized(int cpu)
		{
		return (capacity_of(cpu) * 1024) < (cpu_util(cpu) * capacity_margin);
		}

		/*
		* select_task_rq_fair: Select target runqueue for the waking task in domains
		* that have the 'sd_flag' flag set. In practice, this is SD_BALANCE_WAKE,
		@@ -8036,6 +8041,13 @@ static int need_active_balance(struct lb_env *env)
		return 1;
		}

		if ((capacity_of(env->src_cpu) < capacity_of(env->dst_cpu)) &&
		env->src_rq->cfs.h_nr_running == 1 &&
		cpu_overutilized(env->src_cpu) &&
		!cpu_overutilized(env->dst_cpu)) {
		return 1;
		}

		return unlikely(sd->nr_balance_failed > sd->cache_nice_tries+2);
		}