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)
![]() |