[RFC PATCH 09/12 v2] Intercept idle balancing

From: Yuyang Du
Date: Sun May 11 2014 - 22:24:23 EST


We intercept load balancing to contain the load and load balancing in
the consolidated CPUs according to our consolidating mechanism.

In idle balancing, we do two things:

1) Skip pulling task to the idle non-consolidated CPUs.

2) In addition, for consolidated Idle CPU, we aggressively pull tasks from
non-consolidated CPUs.

Signed-off-by: Yuyang Du <yuyang.du@xxxxxxxxx>
---
kernel/sched/fair.c | 31 +++++++++++++++++++++++++++++++
1 file changed, 31 insertions(+)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index c7a6347..94c7a6a 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -6655,6 +6655,10 @@ out:
return ld_moved;
}

+#ifdef CONFIG_WORKLOAD_CONSOLIDATION
+static DEFINE_PER_CPU(cpumask_var_t, local_cpu_mask);
+#endif
+
/*
* idle_balance is called by schedule() if this_cpu is about to become
* idle. Attempts to pull tasks from other CPUs.
@@ -6666,6 +6670,9 @@ static int idle_balance(struct rq *this_rq)
unsigned long next_balance = jiffies + HZ;
u64 curr_cost = 0;
int this_cpu = this_rq->cpu;
+#ifdef CONFIG_WORKLOAD_CONSOLIDATION
+ struct cpumask *nonshielded = __get_cpu_var(local_cpu_mask);
+#endif

idle_enter_fair(this_rq);
/*
@@ -6684,6 +6691,19 @@ static int idle_balance(struct rq *this_rq)

update_blocked_averages(this_cpu);
rcu_read_lock();
+
+#ifdef CONFIG_WORKLOAD_CONSOLIDATION
+ cpumask_copy(nonshielded, cpu_active_mask);
+
+ /*
+ * if we encounter shielded cpus here, don't do balance on them
+ */
+ workload_consolidation_nonshielded_mask(this_cpu, nonshielded);
+ if (!cpumask_test_cpu(this_cpu, nonshielded))
+ goto unlock;
+ workload_consolidation_unload(nonshielded);
+#endif
+
for_each_domain(this_cpu, sd) {
unsigned long interval;
int continue_balancing = 1;
@@ -6716,6 +6736,9 @@ static int idle_balance(struct rq *this_rq)
if (pulled_task)
break;
}
+#ifdef CONFIG_WORKLOAD_CONSOLIDATION
+unlock:
+#endif
rcu_read_unlock();

raw_spin_lock(&this_rq->lock);
@@ -7709,6 +7732,14 @@ void print_cfs_stats(struct seq_file *m, int cpu)
__init void init_sched_fair_class(void)
{
#ifdef CONFIG_SMP
+#ifdef CONFIG_WORKLOAD_CONSOLIDATION
+ unsigned int i;
+ for_each_possible_cpu(i) {
+ zalloc_cpumask_var_node(&per_cpu(local_cpu_mask, i),
+ GFP_KERNEL, cpu_to_node(i));
+ }
+#endif
+
open_softirq(SCHED_SOFTIRQ, run_rebalance_domains);

#ifdef CONFIG_NO_HZ_COMMON
--
1.7.9.5

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