From acf66d7048e088d08be4f66f56ba2a3ca8aca802 Mon Sep 17 00:00:00 2001
From: Steve Sistare <steven.sistare@oracle.com>
Date: Thu, 11 Nov 2021 16:28:45 +0800
Subject: [PATCH] sched/fair: Provide can_migrate_task_llc

hulk inclusion
category: feature
bugzilla: 38261, https://gitee.com/openeuler/kernel/issues/I49XPZ
CVE: NA

---------------------------

Define a simpler version of can_migrate_task called can_migrate_task_llc
which does not require a struct lb_env argument, and judges whether a
migration from one CPU to another within the same LLC should be allowed.

Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Signed-off-by: Cheng Jian <cj.chengjian@huawei.com>
Reviewed-by: Hanjun Guo <guohanjun@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Reviewed-by: Xie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Reviewed-by: Chen Hui <judy.chenhui@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>
---
 kernel/sched/fair.c | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 5653a3a5cd0e..7bc282428cc4 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -7942,6 +7942,34 @@ int can_migrate_task(struct task_struct *p, struct lb_env *env)
 	return 0;
 }
 
+/*
+ * Return true if task @p can migrate from @rq to @dst_rq in the same LLC.
+ * No need to test for co-locality, and no need to test task_hot(), as sharing
+ * LLC provides cache warmth at that level.
+ */
+static bool
+can_migrate_task_llc(struct task_struct *p, struct rq *rq, struct rq *dst_rq)
+{
+	int dst_cpu = dst_rq->cpu;
+
+	lockdep_assert_held(&rq->lock);
+
+	if (throttled_lb_pair(task_group(p), cpu_of(rq), dst_cpu))
+		return false;
+
+	if (!cpumask_test_cpu(dst_cpu, p->cpus_ptr)) {
+		schedstat_inc(p->se.statistics.nr_failed_migrations_affine);
+		return false;
+	}
+
+	if (task_running(rq, p)) {
+		schedstat_inc(p->se.statistics.nr_failed_migrations_running);
+		return false;
+	}
+
+	return true;
+}
+
 /*
  * detach_task() -- detach the task for the migration from @src_rq to @dst_cpu.
  */
-- 
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