Commit eee4d9fe authored by Peter Zijlstra's avatar Peter Zijlstra
Browse files

delayacct: Add static_branch in scheduler hooks 



Cheaper when delayacct is disabled.

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarIngo Molnar <mingo@kernel.org>
Acked-by: default avatarBalbir Singh <bsingharora@gmail.com>
Acked-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Link: https://lkml.kernel.org/r/20210505111525.248028369@infradead.org
parent 63b3f96e

include/linux/delayacct.h

+8 −0
Original line number Diff line number Diff line
@@ -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);

kernel/delayacct.c

+3 −0
Original line number Diff line number Diff line
@@ -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)