From 0cd7c741f01de13dc1eecf22557593b3514639bb Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Mon, 10 May 2021 14:01:00 +0200 Subject: delayacct: Add sysctl to enable at runtime Just like sched_schedstats, allow runtime enabling (and disabling) of delayacct. This is useful if one forgot to add the delayacct boot time option. Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/YJkhebGJAywaZowX@hirez.programming.kicks-ass.net --- kernel/delayacct.c | 36 ++++++++++++++++++++++++++++++++++-- kernel/sysctl.c | 12 ++++++++++++ 2 files changed, 46 insertions(+), 2 deletions(-) (limited to 'kernel') diff --git a/kernel/delayacct.c b/kernel/delayacct.c index 3f086903b295..51530d5b15a8 100644 --- a/kernel/delayacct.c +++ b/kernel/delayacct.c @@ -18,6 +18,17 @@ DEFINE_STATIC_KEY_FALSE(delayacct_key); int delayacct_on __read_mostly; /* Delay accounting turned on/off */ struct kmem_cache *delayacct_cache; +static void set_delayacct(bool enabled) +{ + if (enabled) { + static_branch_enable(&delayacct_key); + delayacct_on = 1; + } else { + delayacct_on = 0; + static_branch_disable(&delayacct_key); + } +} + static int __init delayacct_setup_enable(char *str) { delayacct_on = 1; @@ -29,9 +40,30 @@ 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_enable(&delayacct_key); + set_delayacct(delayacct_on); +} + +#ifdef CONFIG_PROC_SYSCTL +int sysctl_delayacct(struct ctl_table *table, int write, void *buffer, + size_t *lenp, loff_t *ppos) +{ + int state = delayacct_on; + struct ctl_table t; + int err; + + if (write && !capable(CAP_SYS_ADMIN)) + return -EPERM; + + t = *table; + t.data = &state; + err = proc_dointvec_minmax(&t, write, buffer, lenp, ppos); + if (err < 0) + return err; + if (write) + set_delayacct(state); + return err; } +#endif void __delayacct_tsk_init(struct task_struct *tsk) { diff --git a/kernel/sysctl.c b/kernel/sysctl.c index 14edf84cc571..0afbfc83157a 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -71,6 +71,7 @@ #include #include #include +#include #include "../lib/kstrtox.h" @@ -1727,6 +1728,17 @@ static struct ctl_table kern_table[] = { .extra2 = SYSCTL_ONE, }, #endif /* CONFIG_SCHEDSTATS */ +#ifdef CONFIG_TASK_DELAY_ACCT + { + .procname = "task_delayacct", + .data = NULL, + .maxlen = sizeof(unsigned int), + .mode = 0644, + .proc_handler = sysctl_delayacct, + .extra1 = SYSCTL_ZERO, + .extra2 = SYSCTL_ONE, + }, +#endif /* CONFIG_TASK_DELAY_ACCT */ #ifdef CONFIG_NUMA_BALANCING { .procname = "numa_balancing", -- cgit v1.2.3