From: Srikar Dronamraju <srikar@xxxxxxxxxxxxxxxxxx> commit 2a595721a1fa6b684c1c818f379bef834ac3d65e upstream. Variable sched_numa_balancing toggles numa_balancing feature. Hence moving from a simple read mostly variable to a more apt static_branch. Suggested-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Signed-off-by: Srikar Dronamraju <srikar@xxxxxxxxxxxxxxxxxx> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Mel Gorman <mgorman@xxxxxxx> Cc: Mike Galbraith <efault@xxxxxx> Cc: Rik van Riel <riel@xxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Link: http://lkml.kernel.org/r/1439310261-16124-1-git-send-email-srikar@xxxxxxxxxxxxxxxxxx Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> Signed-off-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> --- kernel/sched/core.c | 12 +++++------- kernel/sched/fair.c | 6 +++--- kernel/sched/sched.h | 6 +----- 3 files changed, 9 insertions(+), 15 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 6cd6ce1fe161..5998e12e14b4 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2114,18 +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; -#ifdef CONFIG_SCHED_DEBUG if (enabled) - sched_feat_set("NUMA"); + static_branch_enable(&sched_numa_balancing); else - sched_feat_set("NO_NUMA"); -#endif /* CONFIG_SCHED_DEBUG */ + static_branch_disable(&sched_numa_balancing); } #ifdef CONFIG_PROC_SYSCTL @@ -2134,7 +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; diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 0d5987e8e329..7975932034f9 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -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 */ @@ -5525,7 +5525,7 @@ 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)) @@ -7811,7 +7811,7 @@ 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); } diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index fb75db386adc..01875872cc94 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -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) { -- 2.6.4 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html