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Date: Fri, 06 Nov 2015 15:02:40 +0300
From: Arseniy Krasnov <a.krasnov@...sung.com>
To: linux@....linux.org.uk, mingo@...hat.com, peterz@...radead.org
Cc: a.krasnov@...sung.com, v.tyrtov@...sung.com,
s.rogachev@...sung.com, linux-kernel@...r.kernel.org,
Tarek Dakhran <t.dakhran@...sung.com>,
Sergey Dyasly <s.dyasly@...sung.com>,
Dmitriy Safonov <d.safonov@...tner.samsung.com>,
Ilya Maximets <i.maximets@...sung.com>
Subject: [PATCH 06/13] hperf_hmp: is_hmp_imbalance introduced.
'is_hmp_imbalance' function calculates imbalance between clusters, four
cases are possible: balancing from/to one of clusters, task swap(when clusters
are balanced) or skip rebalance. Function calculates load difference between two
cluster(cluster load / cluster power) and threshold when balancing is needed.
Signed-off-by: Tarek Dakhran <t.dakhran@...sung.com>
Signed-off-by: Sergey Dyasly <s.dyasly@...sung.com>
Signed-off-by: Dmitriy Safonov <d.safonov@...tner.samsung.com>
Signed-off-by: Arseniy Krasnov <a.krasnov@...sung.com>
Signed-off-by: Ilya Maximets <i.maximets@...sung.com>
---
kernel/sched/fair.c | 103 ++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 103 insertions(+)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index e94fab4..3ab39b6 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -104,9 +104,21 @@ unsigned int __read_mostly sysctl_sched_shares_window = 10000000UL;
extern void hmp_set_cpu_masks(struct cpumask *, struct cpumask *);
static atomic_t a15_nr_hmp_busy = ATOMIC_INIT(0);
static atomic_t a7_nr_hmp_busy = ATOMIC_INIT(0);
+
+/* Total weight of all running tasks on A15 and A7 CPU domains */
+static atomic_long_t a15_total_weight = ATOMIC_LONG_INIT(0);
+static atomic_long_t a7_total_weight = ATOMIC_LONG_INIT(0);
+
static atomic_t hmp_imbalance = ATOMIC_INIT(0);
static unsigned int freq_scale_cpu_power[CONFIG_NR_CPUS];
+
+enum hmp_balance_actions {
+ SWAP_TASKS,
+ A15_TO_A7,
+ A7_TO_A15,
+ SKIP_REBALANCE,
+};
#endif /* CONFIG_HPERF_HMP */
#ifdef CONFIG_CFS_BANDWIDTH
@@ -7016,6 +7028,97 @@ static int should_we_balance(struct lb_env *env)
*/
return balance_cpu == env->dst_cpu;
}
+#ifdef CONFIG_HPERF_HMP
+/**
+ * is_hmp_imbalance(): Calculates imbalance between HMP domains.
+ * @sd: Current sched domain.
+ *
+ * Returns migration direction(see SWAP_TASKS, A15_TO_A7, A7_TO_A15,
+ * SKIP_REBALANCE).
+ *
+ * Imbalance depends on load of tasks on A15 cores and A7 cores,
+ * current CPU's frequencies, and A7 slowdown coefficient which is about 2.4.
+ */
+static int is_hmp_imbalance(struct sched_domain *sd)
+{
+ int imbalance, cpu;
+ int a15_group_power = 0, a7_group_power = 0,
+ hmp_imbalance_min_threshold;
+ int a15_group_load, a7_group_load, a15_a7_group_power;
+ unsigned int a7_balanced_num;
+ int reminder, divisor;
+ unsigned int a15_balanced_num;
+ long long int hmp_imbalance_threshold;
+
+ if (!sd->a15_group) {
+ return SKIP_REBALANCE;
+ }
+
+ if (!sd->a7_group) {
+ return SKIP_REBALANCE;
+ }
+ for_each_online_cpu(cpu) {
+ if (cpu_is_fastest(cpu))
+ a15_group_power += freq_scale_cpu_power[cpu];
+ else
+ a7_group_power += freq_scale_cpu_power[cpu];
+ }
+
+ if (a15_group_power == 0 || a7_group_power == 0) {
+ return SKIP_REBALANCE;
+ }
+
+ a15_balanced_num = 0;
+ a7_balanced_num = 0;
+
+ for_each_online_cpu(cpu) {
+ if (cpu_rq(cpu)->cfs.h_nr_running <= 1) {
+ if (cpu_is_fastest(cpu))
+ a15_balanced_num++;
+ else
+ a7_balanced_num++;
+ }
+ }
+
+ a7_group_load = atomic_long_read(&a7_total_weight);
+
+ if (atomic_long_read(&a7_total_weight) == 0 &&
+ (a15_balanced_num == sd->a15_group->group_weight)) {
+ return SKIP_REBALANCE;
+ }
+
+ a15_group_load = atomic_long_read(&a15_total_weight);
+ a15_a7_group_power = a15_group_power + a7_group_power;
+
+ imbalance = (a15_group_load * 1024) / (a15_group_power) -
+ (a7_group_load * 1024) / (a7_group_power);
+ hmp_imbalance_threshold = ((long long int)NICE_0_LOAD *
+ 1024 * a15_a7_group_power);
+ divisor = 2 * a15_group_power * a7_group_power;
+ hmp_imbalance_threshold = div_s64_rem(hmp_imbalance_threshold,
+ divisor, &reminder);
+ hmp_imbalance_min_threshold = hmp_imbalance_threshold >> 3;
+
+ if (imbalance < hmp_imbalance_min_threshold &&
+ imbalance > -hmp_imbalance_min_threshold) {
+ atomic_set(&hmp_imbalance, 0);
+ return SKIP_REBALANCE;
+ }
+
+ if (imbalance > hmp_imbalance_threshold) {
+ return A15_TO_A7;
+ } else {
+ if (imbalance < -hmp_imbalance_threshold) {
+ if (a7_balanced_num == sd->a7_group->group_weight)
+ return SWAP_TASKS;
+ else
+ return A7_TO_A15;
+ } else {
+ return SWAP_TASKS;
+ }
+ }
+}
+#endif /* CONFIG_HPERF_HMP */
/*
* Check this_cpu to ensure it is balanced within domain. Attempt to move
--
1.9.1
--
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