[RFC PATCH 8/9] sched: introduce per-cpu var next_cpu to track search limit

[subhra mazumdar]

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.mazum...@oracle.com>
---
 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 47969bc..5862d54 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 365c928..cca2b09 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1002,6 +1002,7 @@ 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