The following commit has been merged into the sched/core branch of tip:
Commit-ID: eee4d9fee2544389e5ce5697ed92db67c86d7a9f
Gitweb: https://git.kernel.org/tip/eee4d9fee2544389e5ce5697ed92db67c86d7a9f
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Tue, 04 May 2021 22:43:36 +02:00
Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Wed, 12 May 2021 11:43:25 +02:00
delayacct: Add static_branch in scheduler hooks
Cheaper when delayacct is disabled.
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Reviewed-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Reviewed-by: Ingo Molnar <mingo@xxxxxxxxxx>
Acked-by: Balbir Singh <bsingharora@xxxxxxxxx>
Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Link: https://lkml.kernel.org/r/20210505111525.248028369@xxxxxxxxxxxxx
---
include/linux/delayacct.h | 8 ++++++++
kernel/delayacct.c | 3 +++
2 files changed, 11 insertions(+)
diff --git a/include/linux/delayacct.h b/include/linux/delayacct.h
index 21651f9..57fefa5 100644
--- a/include/linux/delayacct.h
+++ b/include/linux/delayacct.h
@@ -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);
diff --git a/kernel/delayacct.c b/kernel/delayacct.c
index 3a0b910..63012fd 100644
--- a/kernel/delayacct.c
+++ b/kernel/delayacct.c
@@ -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)
|