Commit 23cea43f authored by Steve Sistare's avatar Steve Sistare Committed by Cheng Yu
Browse files

sched/fair: Provide can_migrate_task_llc 

maillist inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I8PIYZ
CVE: NA

Reference: https://lore.kernel.org/lkml/1541767840-93588-8-git-send-email-steven.sistare@oracle.com/



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

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: default avatarSteve Sistare <steven.sistare@oracle.com>
Signed-off-by: default avatarCheng Yu <serein.chengyu@huawei.com>
parent 1542af1d

kernel/sched/fair.c

+28 −0
Original line number Diff line number Diff line
@@ -9478,6 +9478,34 @@ 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_rq_held(rq);



	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->stats.nr_failed_migrations_affine);

		return false;

	}



	if (task_on_cpu(rq, p)) {

		schedstat_inc(p->stats.nr_failed_migrations_running);

		return false;

	}



	return true;

}



/*

 * detach_task() -- detach the task for the migration from @src_rq to @dst_cpu.

 */