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sched: Use jump_labels for sched_feat

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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>
This commit is contained in:
Peter Zijlstra 2011-07-06 14:20:14 +02:00 committed by Ingo Molnar
parent be726ffd1e
commit f8b6d1cc7d
3 changed files with 81 additions and 22 deletions
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46
kernel/sched/core.c
View File

@ -149,7 +149,7 @@ static int sched_feat_show(struct seq_file *m, void *v)
{
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 @@ static int sched_feat_show(struct seq_file *m, void *v)
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 @@ sched_feat_write(struct file *filp, const char __user *ubuf,
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 @@ static __init int sched_init_debug(void)
return 0;
}
late_initcall(sched_init_debug);
#endif
#endif /* CONFIG_SCHED_DEBUG */
/*
* Number of tasks to iterate in a single balance run.

30
kernel/sched/features.h
View File

@ -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 @@ SCHED_FEAT(START_DEBIT, 1)
* 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)

27
kernel/sched/sched.h
View File

@ -581,6 +581,7 @@ static inline void __set_task_cpu(struct task_struct *p, unsigned int cpu)
* 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 @@ extern const_debug unsigned int sysctl_sched_features;
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)
{