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delayacct: Add static_branch in scheduler hooks

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Cheaper when delayacct is disabled.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Balbir Singh <bsingharora@gmail.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Link: https://lkml.kernel.org/r/20210505111525.248028369@infradead.org
This commit is contained in:
Peter Zijlstra 2021-05-04 22:43:36 +02:00
parent 63b3f96e1a
commit eee4d9fee2
2 changed files with 11 additions and 0 deletions
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8
include/linux/delayacct.h
View File

@ -58,8 +58,10 @@ struct task_delay_info {
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/jump_label.h>
#ifdef CONFIG_TASK_DELAY_ACCT
DECLARE_STATIC_KEY_TRUE(delayacct_key);
extern int delayacct_on; /* Delay accounting turned on/off */
extern struct kmem_cache *delayacct_cache;
extern void delayacct_init(void);
@ -114,6 +116,9 @@ static inline void delayacct_tsk_free(struct task_struct *tsk)
static inline void delayacct_blkio_start(void)
{
if (!static_branch_likely(&delayacct_key))
return;
delayacct_set_flag(current, DELAYACCT_PF_BLKIO);
if (current->delays)
__delayacct_blkio_start();
@ -121,6 +126,9 @@ static inline void delayacct_blkio_start(void)
static inline void delayacct_blkio_end(struct task_struct *p)
{
if (!static_branch_likely(&delayacct_key))
return;
if (p->delays)
__delayacct_blkio_end(p);
delayacct_clear_flag(p, DELAYACCT_PF_BLKIO);

3
kernel/delayacct.c
View File

@ -14,6 +14,7 @@
#include <linux/delayacct.h>
#include <linux/module.h>
DEFINE_STATIC_KEY_TRUE(delayacct_key);
int delayacct_on __read_mostly = 1; /* Delay accounting turned on/off */
struct kmem_cache *delayacct_cache;
@ -28,6 +29,8 @@ void delayacct_init(void)
{
delayacct_cache = KMEM_CACHE(task_delay_info, SLAB_PANIC|SLAB_ACCOUNT);
delayacct_tsk_init(&init_task);
if (!delayacct_on)
static_branch_disable(&delayacct_key);
}
void __delayacct_tsk_init(struct task_struct *tsk)