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Commit 2a595721 authored by Srikar Dronamraju's avatar Srikar Dronamraju Committed by Ingo Molnar
Browse files

sched/numa: Convert sched_numa_balancing to a static_branch 



Variable sched_numa_balancing toggles numa_balancing feature. Hence
moving from a simple read mostly variable to a more apt static_branch.

Suggested-by: default avatarPeter Zijlstra <peterz@infradead.org>
Signed-off-by: default avatarSrikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1439310261-16124-1-git-send-email-srikar@linux.vnet.ibm.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 2b49d84b

kernel/sched/core.c

+7 −3
Original line number Diff line number Diff line
@@ -2114,12 +2114,16 @@ static void __sched_fork(unsigned long clone_flags, struct task_struct *p) 
#endif /* CONFIG_NUMA_BALANCING */

}



DEFINE_STATIC_KEY_FALSE(sched_numa_balancing);



#ifdef CONFIG_NUMA_BALANCING

__read_mostly bool sched_numa_balancing;



void set_numabalancing_state(bool enabled)

{

	sched_numa_balancing = enabled;

	if (enabled)

		static_branch_enable(&sched_numa_balancing);

	else

		static_branch_disable(&sched_numa_balancing);

}



#ifdef CONFIG_PROC_SYSCTL
@@ -2128,7 +2132,7 @@ int sysctl_numa_balancing(struct ctl_table *table, int write, 
{

	struct ctl_table t;

	int err;

	int state = sched_numa_balancing;

	int state = static_branch_likely(&sched_numa_balancing);



	if (write && !capable(CAP_SYS_ADMIN))

		return -EPERM;

kernel/sched/fair.c

+3 −3
Original line number Diff line number Diff line
@@ -2069,7 +2069,7 @@ void task_numa_fault(int last_cpupid, int mem_node, int pages, int flags) 
	int local = !!(flags & TNF_FAULT_LOCAL);

	int priv;



	if (!sched_numa_balancing)

	if (!static_branch_likely(&sched_numa_balancing))

		return;



	/* for example, ksmd faulting in a user's mm */
@@ -5562,7 +5562,7 @@ static int migrate_degrades_locality(struct task_struct *p, struct lb_env *env) 
	unsigned long src_faults, dst_faults;

	int src_nid, dst_nid;



	if (!sched_numa_balancing)

	if (!static_branch_likely(&sched_numa_balancing))

		return -1;



	if (!p->numa_faults || !(env->sd->flags & SD_NUMA))
@@ -7874,7 +7874,7 @@ static void task_tick_fair(struct rq *rq, struct task_struct *curr, int queued) 
		entity_tick(cfs_rq, se, queued);

	}



	if (sched_numa_balancing)

	if (!static_branch_unlikely(&sched_numa_balancing))

		task_tick_numa(rq, curr);

}

kernel/sched/sched.h

+1 −5
Original line number Diff line number Diff line
@@ -1003,11 +1003,7 @@ extern struct static_key sched_feat_keys[__SCHED_FEAT_NR]; 
#define sched_feat(x) (sysctl_sched_features & (1UL << __SCHED_FEAT_##x))

#endif /* SCHED_DEBUG && HAVE_JUMP_LABEL */



#ifdef CONFIG_NUMA_BALANCING

extern bool sched_numa_balancing;

#else

#define sched_numa_balancing (0)

#endif /* CONFIG_NUMA_BALANCING */

extern struct static_key_false sched_numa_balancing;



static inline u64 global_rt_period(void)

{