sched: Use jump_labels for sched_feat
Now that we initialize jump_labels before sched_init() we can use them
for the debug features without having to worry about a window where
they have the wrong setting.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/n/tip-vpreo4hal9e0kzqmg5y0io2k@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 9ac22d2..3c5b21e 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -149,7 +149,7 @@
{
int i;
- for (i = 0; sched_feat_names[i]; i++) {
+ for (i = 0; i < __SCHED_FEAT_NR; i++) {
if (!(sysctl_sched_features & (1UL << i)))
seq_puts(m, "NO_");
seq_printf(m, "%s ", sched_feat_names[i]);
@@ -159,6 +159,36 @@
return 0;
}
+#ifdef HAVE_JUMP_LABEL
+
+#define jump_label_key__true jump_label_key_enabled
+#define jump_label_key__false jump_label_key_disabled
+
+#define SCHED_FEAT(name, enabled) \
+ jump_label_key__##enabled ,
+
+struct jump_label_key sched_feat_keys[__SCHED_FEAT_NR] = {
+#include "features.h"
+};
+
+#undef SCHED_FEAT
+
+static void sched_feat_disable(int i)
+{
+ if (jump_label_enabled(&sched_feat_keys[i]))
+ jump_label_dec(&sched_feat_keys[i]);
+}
+
+static void sched_feat_enable(int i)
+{
+ if (!jump_label_enabled(&sched_feat_keys[i]))
+ jump_label_inc(&sched_feat_keys[i]);
+}
+#else
+static void sched_feat_disable(int i) { };
+static void sched_feat_enable(int i) { };
+#endif /* HAVE_JUMP_LABEL */
+
static ssize_t
sched_feat_write(struct file *filp, const char __user *ubuf,
size_t cnt, loff_t *ppos)
@@ -182,17 +212,20 @@
cmp += 3;
}
- for (i = 0; sched_feat_names[i]; i++) {
+ for (i = 0; i < __SCHED_FEAT_NR; i++) {
if (strcmp(cmp, sched_feat_names[i]) == 0) {
- if (neg)
+ if (neg) {
sysctl_sched_features &= ~(1UL << i);
- else
+ sched_feat_disable(i);
+ } else {
sysctl_sched_features |= (1UL << i);
+ sched_feat_enable(i);
+ }
break;
}
}
- if (!sched_feat_names[i])
+ if (i == __SCHED_FEAT_NR)
return -EINVAL;
*ppos += cnt;
@@ -221,8 +254,7 @@
return 0;
}
late_initcall(sched_init_debug);
-
-#endif
+#endif /* CONFIG_SCHED_DEBUG */
/*
* Number of tasks to iterate in a single balance run.
diff --git a/kernel/sched/features.h b/kernel/sched/features.h
index 8480224..e61fd73 100644
--- a/kernel/sched/features.h
+++ b/kernel/sched/features.h
@@ -3,13 +3,13 @@
* them to run sooner, but does not allow tons of sleepers to
* rip the spread apart.
*/
-SCHED_FEAT(GENTLE_FAIR_SLEEPERS, 1)
+SCHED_FEAT(GENTLE_FAIR_SLEEPERS, true)
/*
* Place new tasks ahead so that they do not starve already running
* tasks
*/
-SCHED_FEAT(START_DEBIT, 1)
+SCHED_FEAT(START_DEBIT, true)
/*
* Based on load and program behaviour, see if it makes sense to place
@@ -17,54 +17,54 @@
* improve cache locality. Typically used with SYNC wakeups as
* generated by pipes and the like, see also SYNC_WAKEUPS.
*/
-SCHED_FEAT(AFFINE_WAKEUPS, 1)
+SCHED_FEAT(AFFINE_WAKEUPS, true)
/*
* Prefer to schedule the task we woke last (assuming it failed
* wakeup-preemption), since its likely going to consume data we
* touched, increases cache locality.
*/
-SCHED_FEAT(NEXT_BUDDY, 0)
+SCHED_FEAT(NEXT_BUDDY, false)
/*
* Prefer to schedule the task that ran last (when we did
* wake-preempt) as that likely will touch the same data, increases
* cache locality.
*/
-SCHED_FEAT(LAST_BUDDY, 1)
+SCHED_FEAT(LAST_BUDDY, true)
/*
* Consider buddies to be cache hot, decreases the likelyness of a
* cache buddy being migrated away, increases cache locality.
*/
-SCHED_FEAT(CACHE_HOT_BUDDY, 1)
+SCHED_FEAT(CACHE_HOT_BUDDY, true)
/*
* Use arch dependent cpu power functions
*/
-SCHED_FEAT(ARCH_POWER, 0)
+SCHED_FEAT(ARCH_POWER, false)
-SCHED_FEAT(HRTICK, 0)
-SCHED_FEAT(DOUBLE_TICK, 0)
-SCHED_FEAT(LB_BIAS, 1)
+SCHED_FEAT(HRTICK, false)
+SCHED_FEAT(DOUBLE_TICK, false)
+SCHED_FEAT(LB_BIAS, true)
/*
* Spin-wait on mutex acquisition when the mutex owner is running on
* another cpu -- assumes that when the owner is running, it will soon
* release the lock. Decreases scheduling overhead.
*/
-SCHED_FEAT(OWNER_SPIN, 1)
+SCHED_FEAT(OWNER_SPIN, true)
/*
* Decrement CPU power based on time not spent running tasks
*/
-SCHED_FEAT(NONTASK_POWER, 1)
+SCHED_FEAT(NONTASK_POWER, true)
/*
* Queue remote wakeups on the target CPU and process them
* using the scheduler IPI. Reduces rq->lock contention/bounces.
*/
-SCHED_FEAT(TTWU_QUEUE, 1)
+SCHED_FEAT(TTWU_QUEUE, true)
-SCHED_FEAT(FORCE_SD_OVERLAP, 0)
-SCHED_FEAT(RT_RUNTIME_SHARE, 1)
+SCHED_FEAT(FORCE_SD_OVERLAP, false)
+SCHED_FEAT(RT_RUNTIME_SHARE, true)
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index c248016..d8d3613 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -581,6 +581,7 @@
* Tunables that become constants when CONFIG_SCHED_DEBUG is off:
*/
#ifdef CONFIG_SCHED_DEBUG
+# include <linux/jump_label.h>
# define const_debug __read_mostly
#else
# define const_debug const
@@ -593,11 +594,37 @@
enum {
#include "features.h"
+ __SCHED_FEAT_NR,
};
#undef SCHED_FEAT
+#if defined(CONFIG_SCHED_DEBUG) && defined(HAVE_JUMP_LABEL)
+static __always_inline bool static_branch__true(struct jump_label_key *key)
+{
+ return likely(static_branch(key)); /* Not out of line branch. */
+}
+
+static __always_inline bool static_branch__false(struct jump_label_key *key)
+{
+ return unlikely(static_branch(key)); /* Out of line branch. */
+}
+
+#define SCHED_FEAT(name, enabled) \
+static __always_inline bool static_branch_##name(struct jump_label_key *key) \
+{ \
+ return static_branch__##enabled(key); \
+}
+
+#include "features.h"
+
+#undef SCHED_FEAT
+
+extern struct jump_label_key sched_feat_keys[__SCHED_FEAT_NR];
+#define sched_feat(x) (static_branch_##x(&sched_feat_keys[__SCHED_FEAT_##x]))
+#else /* !(SCHED_DEBUG && HAVE_JUMP_LABEL) */
#define sched_feat(x) (sysctl_sched_features & (1UL << __SCHED_FEAT_##x))
+#endif /* SCHED_DEBUG && HAVE_JUMP_LABEL */
static inline u64 global_rt_period(void)
{
