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Commit 4c957100 authored by Pavankumar Kondeti's avatar Pavankumar Kondeti Committed by Gerrit - the friendly Code Review server
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core_ctl: redo offline_delay_ms tunable implementation 



The offline_delay_ms tunable is supposed to give hysteresis
effect by delaying the CPU isolation. The current implementation
is not enforcing this correctly due to which we see a CPU is
getting isolated immediately in the next evaluation cycle.

Allow isolating a CPU only if offline_delay_ms is passed
after since the last time we isolated/unisolated/evaluated
without changing the need CPUs.

Change-Id: I9a2c55f8cfbf2fcd69fa68044f7daf9aea88fba0
Signed-off-by: default avatarPavankumar Kondeti <pkondeti@codeaurora.org>
Signed-off-by: default avatarSatya Durga Srinivasu Prabhala <satyap@codeaurora.org>
parent d867c6f4

kernel/sched/core_ctl.c

+11 −8
Original line number Diff line number Diff line 
/* Copyright (c) 2014-2016, The Linux Foundation. All rights reserved.

/* Copyright (c) 2014-2017, The Linux Foundation. All rights reserved.

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 and
@@ -36,7 +36,7 @@ struct cluster_data { 
	cpumask_t cpu_mask;

	unsigned int need_cpus;

	unsigned int task_thres;

	s64 last_isolate_ts;

	s64 need_ts;

	struct list_head lru;

	bool pending;

	spinlock_t pending_lock;
@@ -549,6 +549,7 @@ static bool eval_need(struct cluster_data *cluster) 
	bool need_flag = false;

	unsigned int active_cpus;

	unsigned int new_need;

	s64 now;



	if (unlikely(!cluster->inited))

		return 0;
@@ -573,9 +574,10 @@ static bool eval_need(struct cluster_data *cluster) 
	need_flag = adjustment_possible(cluster, new_need);



	last_need = cluster->need_cpus;

	cluster->need_cpus = new_need;

	now = ktime_to_ms(ktime_get());



	if (!need_flag) {

	if (new_need == last_need) {

		cluster->need_ts = now;

		spin_unlock_irqrestore(&state_lock, flags);

		return 0;

	}
@@ -583,12 +585,15 @@ static bool eval_need(struct cluster_data *cluster) 
	if (need_cpus > cluster->active_cpus) {

		ret = 1;

	} else if (need_cpus < cluster->active_cpus) {

		s64 now = ktime_to_ms(ktime_get());

		s64 elapsed = now - cluster->last_isolate_ts;

		s64 elapsed = now - cluster->need_ts;



		ret = elapsed >= cluster->offline_delay_ms;

	}



	if (ret) {

		cluster->need_ts = now;

		cluster->need_cpus = new_need;

	}

	trace_core_ctl_eval_need(cluster->first_cpu, last_need, need_cpus,

				 ret && need_flag);

	spin_unlock_irqrestore(&state_lock, flags);
@@ -746,7 +751,6 @@ static void try_to_isolate(struct cluster_data *cluster, unsigned int need) 
		if (!sched_isolate_cpu(c->cpu)) {

			c->isolated_by_us = true;

			move_cpu_lru(c);

			cluster->last_isolate_ts = ktime_to_ms(ktime_get());

		} else {

			pr_debug("Unable to isolate CPU%u\n", c->cpu);

		}
@@ -779,7 +783,6 @@ static void try_to_isolate(struct cluster_data *cluster, unsigned int need) 
		if (!sched_isolate_cpu(c->cpu)) {

			c->isolated_by_us = true;

			move_cpu_lru(c);

			cluster->last_isolate_ts = ktime_to_ms(ktime_get());

		} else {

			pr_debug("Unable to isolate CPU%u\n", c->cpu);

		}