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delayacct: Add sysctl to enable at runtime

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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) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/YJkhebGJAywaZowX@hirez.programming.kicks-ass.net
This commit is contained in:
Peter Zijlstra
2021-05-10 14:01:00 +02:00
parent e4042ad492
commit 0cd7c741f0
4 changed files with 54 additions and 4 deletions
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kernel/delayacct.c
+34 -2
View File
@@ -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;
@@ -29,10 +40,31 @@ 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)
{
tsk->delays = kmem_cache_zalloc(delayacct_cache, GFP_KERNEL);