tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/YJkhebGJAywaZowX@hirez.programming.kicks-ass.net
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-2
Documentation/accounting/delay-accounting.rst
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Documentation/accounting/delay-accounting.rst
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delayacct
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to the kernel boot options. The rest of the instructions
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below assume this has been done.
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to the kernel boot options. The rest of the instructions below assume this has
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been done. Alternatively, use sysctl kernel.task_delayacct to switch the state
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at runtime. Note however that only tasks started after enabling it will have
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delayacct information.
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After the system has booted up, use a utility
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similar to getdelays.c to access the delays
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include/linux/delayacct.h
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include/linux/delayacct.h
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extern int delayacct_on; /* Delay accounting turned on/off */
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extern struct kmem_cache *delayacct_cache;
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extern void delayacct_init(void);
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extern int sysctl_delayacct(struct ctl_table *table, int write, void *buffer,
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size_t *lenp, loff_t *ppos);
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extern void __delayacct_tsk_init(struct task_struct *);
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extern void __delayacct_tsk_exit(struct task_struct *);
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extern void __delayacct_blkio_start(void);
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kernel/delayacct.c
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kernel/delayacct.c
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int delayacct_on __read_mostly; /* Delay accounting turned on/off */
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struct kmem_cache *delayacct_cache;
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static void set_delayacct(bool enabled)
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{
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if (enabled) {
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static_branch_enable(&delayacct_key);
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delayacct_on = 1;
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} else {
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delayacct_on = 0;
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static_branch_disable(&delayacct_key);
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}
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}
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static int __init delayacct_setup_enable(char *str)
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{
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delayacct_on = 1;
···
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{
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delayacct_cache = KMEM_CACHE(task_delay_info, SLAB_PANIC|SLAB_ACCOUNT);
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delayacct_tsk_init(&init_task);
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if (delayacct_on)
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static_branch_enable(&delayacct_key);
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set_delayacct(delayacct_on);
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}
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#ifdef CONFIG_PROC_SYSCTL
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int sysctl_delayacct(struct ctl_table *table, int write, void *buffer,
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size_t *lenp, loff_t *ppos)
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{
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int state = delayacct_on;
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struct ctl_table t;
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int err;
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if (write && !capable(CAP_SYS_ADMIN))
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return -EPERM;
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t = *table;
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t.data = &state;
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err = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
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if (err < 0)
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return err;
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if (write)
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set_delayacct(state);
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return err;
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}
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#endif
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void __delayacct_tsk_init(struct task_struct *tsk)
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{
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kernel/sysctl.c
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kernel/sysctl.c
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#include <linux/coredump.h>
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#include <linux/latencytop.h>
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#include <linux/pid.h>
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#include <linux/delayacct.h>
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#include "../lib/kstrtox.h"
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···
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.extra2 = SYSCTL_ONE,
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},
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#endif /* CONFIG_SCHEDSTATS */
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#ifdef CONFIG_TASK_DELAY_ACCT
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{
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.procname = "task_delayacct",
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.data = NULL,
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.maxlen = sizeof(unsigned int),
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.mode = 0644,
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.proc_handler = sysctl_delayacct,
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.extra1 = SYSCTL_ZERO,
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.extra2 = SYSCTL_ONE,
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},
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#endif /* CONFIG_TASK_DELAY_ACCT */
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#ifdef CONFIG_NUMA_BALANCING
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{
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.procname = "numa_balancing",