Commit 3b2c79ff authored by He Yujie's avatar He Yujie
Browse files

sched/dynamic_affinity: fix preffered_cpu offline problem 

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/IB42TC


CVE: NA

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

After the preferred_cpu goes offline, the core selection of
dynamic affinity does not check whether the preferred_cpu is
valid. As a result, related dynamic affinity processes are
concentrated on a shared_cpu.

This patch resolves this problem to checks whether the preferred_cpu
is valid and compares only the usage threshold of the valid preferred_cpu.

Fixes: 70a232a5 ("sched: Adjust wakeup cpu range according CPU util dynamicly")
Signed-off-by: default avatarHe Yujie <coka.heyujie@huawei.com>
parent d5c3ef07

kernel/sched/fair.c

+11 −2
Original line number Diff line number Diff line
@@ -7248,6 +7248,7 @@ static void set_task_select_cpus(struct task_struct *p, int *idlest_cpu, 
	struct task_group *tg;

	long spare;

	int cpu, mode;

	int nr_cpus_valid = 0;



	rcu_read_lock();

	mode = dynamic_affinity_mode(p);
@@ -7265,7 +7266,7 @@ static void set_task_select_cpus(struct task_struct *p, int *idlest_cpu, 


	/* manual mode */

	tg = task_group(p);

	for_each_cpu(cpu, p->prefer_cpus) {

	for_each_cpu_and(cpu, p->prefer_cpus, cpu_online_mask) {

		if (unlikely(!tg->se[cpu]))

			continue;
@@ -7289,10 +7290,18 @@ static void set_task_select_cpus(struct task_struct *p, int *idlest_cpu, 


		util_avg_sum += tg->se[cpu]->avg.util_avg;

		tg_capacity += capacity_of(cpu);

		nr_cpus_valid++;

	}

	rcu_read_unlock();



	if (tg_capacity > cpumask_weight(p->prefer_cpus) &&

	/*

	 * Follow cases should select cpus_ptr, checking by condition of

	 * tg_capacity > nr_cpus_valid:

	 * 1. all prefer_cpus offline;

	 * 2. all prefer_cpus has no cfs capaicity(tg_capacity =

	 * nr_cpus_valid * 1)

	 */

	if (tg_capacity > nr_cpus_valid &&

	    util_avg_sum * 100 <= tg_capacity * sysctl_sched_util_low_pct) {

		p->select_cpus = p->prefer_cpus;

		if (sd_flag & SD_BALANCE_WAKE)