Commit 4ff53cf9 authored by Cheng Yu's avatar Cheng Yu
Browse files

sched/fair: Set the maximum number of steal attempts 

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/IAQWPQ



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

When there are a large number of cfs tasks on rq, but only a few
steal_task tasks, steal_from may often fail to pull tasks. To avoid
multiple pull task failures, we can set the maximum number of steal
tasks through sysctl_sched_max_steal_count. The default value is 32 and
the maximum value is 1024.

Signed-off-by: default avatarCheng Yu <serein.chengyu@huawei.com>
parent 433c0b72

include/linux/sched/sysctl.h

+4 −0
Original line number Diff line number Diff line
@@ -39,6 +39,10 @@ extern int sysctl_sched_util_low_pct; 
extern int sysctl_sched_util_ratio;

#endif



#ifdef CONFIG_SCHED_STEAL

extern int sysctl_sched_max_steal_count;

#endif



#ifdef CONFIG_QOS_SCHED_SMART_GRID

extern unsigned int sysctl_smart_grid_strategy_ctrl;

extern int sysctl_affinity_adjust_delay_ms;

kernel/sched/fair.c

+7 −0
Original line number Diff line number Diff line
@@ -13183,6 +13183,7 @@ void trigger_load_balance(struct rq *rq) 
}



#ifdef CONFIG_SCHED_STEAL

int sysctl_sched_max_steal_count = 32;

/*

 * Search the runnable tasks in @cfs_rq in order of next to run, and find

 * the first one that can be migrated to @dst_rq.  @cfs_rq is locked on entry.
@@ -13194,14 +13195,20 @@ detach_next_task(struct cfs_rq *cfs_rq, struct rq *dst_rq) 
	int dst_cpu = dst_rq->cpu;

	struct task_struct *p;

	struct rq *rq = rq_of(cfs_rq);

	int count = 1;



	lockdep_assert_rq_held(rq_of(cfs_rq));



	list_for_each_entry_reverse(p, &rq->cfs_tasks, se.group_node) {

		if (count > sysctl_sched_max_steal_count)

			break;



		if (can_migrate_task_llc(p, rq, dst_rq)) {

			detach_task(p, rq, dst_cpu);

			return p;

		}



		count++;

	}

	return NULL;

}

kernel/sysctl.c

+14 −0
Original line number Diff line number Diff line
@@ -131,6 +131,9 @@ static int hundred_thousand = 100000; 
#ifdef CONFIG_PERF_EVENTS

static int six_hundred_forty_kb = 640 * 1024;

#endif

#ifdef CONFIG_SCHED_STEAL

static int max_steal_count = 1024;

#endif



/* this is needed for the proc_doulongvec_minmax of vm_dirty_bytes */

static unsigned long dirty_bytes_min = 2 * PAGE_SIZE;
@@ -2827,6 +2830,17 @@ static struct ctl_table kern_table[] = { 
		.extra1         = SYSCTL_ZERO,

	},

#endif

#ifdef CONFIG_SCHED_STEAL

	{

		.procname       = "sched_max_steal_count",

		.data           = &sysctl_sched_max_steal_count,

		.maxlen         = sizeof(sysctl_sched_max_steal_count),

		.mode           = 0644,

		.proc_handler   = proc_dointvec_minmax,

		.extra1         = SYSCTL_ONE,

		.extra2         = &max_steal_count,

	},

#endif

#ifdef CONFIG_QOS_SCHED_SMART_GRID

	{

		.procname	= "smart_grid_strategy_ctrl",