Unverified Commit 2b25e7e1 authored by openeuler-ci-bot's avatar openeuler-ci-bot Committed by Gitee
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!879 [sync] PR-877: sched: fix performance degradation on lmbench 

Merge Pull Request from: @openeuler-sync-bot 
 

Origin pull request: 
https://gitee.com/openeuler/kernel/pulls/877 
 
There are worse performance with the 'Fixes'
when running "./lat_ctx -P $SYNC_MAX -s 64 16".

The 'Fixes' which allocates memory for p->prefer_cpus
even if "prefer_cpus" not be set.

Before the 'Fixes', only test "p->prefer_cpus",
after, add test "!cpumask_empty(p->prefer_cpus)"
which causing performance degradation.

select_task_rq_fair
  ->set_task_select_cpus
    ->prefer_cpus_valid  ----  test cpumask_empty(p->prefer_cpus) 
 
Link:https://gitee.com/openeuler/kernel/pulls/879

 

Reviewed-by: default avatarZucheng Zheng <zhengzucheng@huawei.com>
Signed-off-by: default avatarZheng Zengkai <zhengzengkai@huawei.com>
parents c1481312 c6aaa310

fs/proc/base.c

+6 −0
Original line number Diff line number Diff line
@@ -3298,6 +3298,12 @@ static ssize_t preferred_cpuset_write(struct file *file, const char __user *buf, 
	if (retval < 0)

		goto out_free_cpumask;



	if (!cpumask_empty(new_mask)) {

		cpus_read_lock();

		dynamic_affinity_enable();

		cpus_read_unlock();

	}



	retval = count;



out_free_cpumask:

include/linux/sched.h

+1 −0
Original line number Diff line number Diff line
@@ -2227,6 +2227,7 @@ int set_prefer_cpus_ptr(struct task_struct *p, 
			const struct cpumask *new_mask);

int sched_prefer_cpus_fork(struct task_struct *p, struct cpumask *mask);

void sched_prefer_cpus_free(struct task_struct *p);

void dynamic_affinity_enable(void);

#endif



#ifdef CONFIG_BPF_SCHED

kernel/cgroup/cpuset.c

+3 −0
Original line number Diff line number Diff line
@@ -734,6 +734,9 @@ static int update_prefer_cpumask(struct cpuset *cs, struct cpuset *trialcs, 


	update_tasks_prefer_cpumask(trialcs);



	if (!cpumask_empty(trialcs->prefer_cpus))

		dynamic_affinity_enable();



	spin_lock_irq(&callback_lock);

	cpumask_copy(cs->prefer_cpus, trialcs->prefer_cpus);

	spin_unlock_irq(&callback_lock);

kernel/sched/fair.c

+24 −0
Original line number Diff line number Diff line
@@ -7067,6 +7067,27 @@ static int find_energy_efficient_cpu(struct task_struct *p, int prev_cpu) 
}



#ifdef CONFIG_QOS_SCHED_DYNAMIC_AFFINITY



#ifdef CONFIG_JUMP_LABEL

static DEFINE_STATIC_KEY_FALSE(__dynamic_affinity_used);



static inline bool dynamic_affinity_used(void)

{

	return static_branch_unlikely(&__dynamic_affinity_used);

}



void dynamic_affinity_enable(void)

{

	static_branch_enable_cpuslocked(&__dynamic_affinity_used);

}



#else /* CONFIG_JUMP_LABEL */

static bool dynamic_affinity_used(void)

{

	return true;

}

#endif



/*

 * Low utilization threshold for CPU

 *
@@ -7076,6 +7097,9 @@ int sysctl_sched_util_low_pct = 85; 


static inline bool prefer_cpus_valid(struct task_struct *p)

{

	if (!dynamic_affinity_used())

		return false;



	return p->prefer_cpus &&

	       !cpumask_empty(p->prefer_cpus) &&

	       !cpumask_equal(p->prefer_cpus, p->cpus_ptr) &&