[PATCH v3 2/7] sched: introduce per-cpu var next_cpu to track search limit

From: subhra mazumdar
Date: Sat Jun 08 2019 - 22:00:16 EST


Introduce a per-cpu variable to track the limit upto which idle cpu search
was done in select_idle_cpu(). This will help to start the search next time
from there. This is necessary for rotating the search window over entire
LLC domain.

Signed-off-by: subhra mazumdar <subhra.mazumdar@xxxxxxxxxx>
---
kernel/sched/core.c | 2 ++
kernel/sched/sched.h | 1 +
2 files changed, 3 insertions(+)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 874c427..80657fc 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -24,6 +24,7 @@
#include <trace/events/sched.h>

DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
+DEFINE_PER_CPU_SHARED_ALIGNED(int, next_cpu);

#if defined(CONFIG_SCHED_DEBUG) && defined(CONFIG_JUMP_LABEL)
/*
@@ -5966,6 +5967,7 @@ void __init sched_init(void)
for_each_possible_cpu(i) {
struct rq *rq;

+ per_cpu(next_cpu, i) = -1;
rq = cpu_rq(i);
raw_spin_lock_init(&rq->lock);
rq->nr_running = 0;
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index b52ed1a..4cecfa2 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -994,6 +994,7 @@ static inline void update_idle_core(struct rq *rq) { }
#endif

DECLARE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
+DECLARE_PER_CPU_SHARED_ALIGNED(int, next_cpu);

#define cpu_rq(cpu) (&per_cpu(runqueues, (cpu)))
#define this_rq() this_cpu_ptr(&runqueues)
--
2.9.3