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From:   subhra mazumdar <subhra.mazumdar@oracle.com>
To:     linux-kernel@vger.kernel.org
Cc:     peterz@infradead.org, mingo@redhat.com, steven.sistare@oracle.com,
        dhaval.giani@oracle.com, rohit.k.jain@oracle.com,
        daniel.lezcano@linaro.org
Subject: [PATCH 2/5] sched: introduce per-cpu var next_cpu to track search limit
Date:   Tue, 12 Jun 2018 10:49:59 -0700
Message-Id: <20180612175002.31453-3-subhra.mazumdar@oracle.com>
In-Reply-To: <20180612175002.31453-1-subhra.mazumdar@oracle.com>
References: <20180612175002.31453-1-subhra.mazumdar@oracle.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

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@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 8d59b25..b3e4ec1 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -20,6 +20,7 @@
 #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(HAVE_JUMP_LABEL)
 /*
@@ -5996,6 +5997,7 @@ 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 67702b4..eb12b50 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -912,6 +912,7 @@ 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