| Message ID | YJkhebGJAywaZowX@hirez.programming.kicks-ass.net (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | sched,delayacct: Some cleanups | expand |
On Mon, May 10, 2021 at 02:05:13PM +0200, Peter Zijlstra wrote: > > 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> > --- > Documentation/accounting/delay-accounting.rst | 6 ++-- > kernel/delayacct.c | 36 ++++++++++++++++++++++++-- > kernel/sysctl.c | 12 ++++++++ > 3 files changed, 50 insertions(+), 4 deletions(-) *sigh*, the below hunk went missing.. --- a/include/linux/delayacct.h +++ b/include/linux/delayacct.h @@ -65,6 +65,10 @@ DECLARE_STATIC_KEY_FALSE(delayacct_key); extern int delayacct_on; /* Delay accounting turned on/off */ extern struct kmem_cache *delayacct_cache; extern void delayacct_init(void); + +extern int sysctl_delayacct(struct ctl_table *table, int write, void *buffer, + size_t *lenp, loff_t *ppos); + extern void __delayacct_tsk_init(struct task_struct *); extern void __delayacct_tsk_exit(struct task_struct *); extern void __delayacct_blkio_start(void);
On Mon, May 10, 2021 at 02:05:13PM +0200, Peter Zijlstra wrote: > > 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> > --- > Documentation/accounting/delay-accounting.rst | 6 ++-- > kernel/delayacct.c | 36 ++++++++++++++++++++++++-- > kernel/sysctl.c | 12 ++++++++ > 3 files changed, 50 insertions(+), 4 deletions(-) > Update sysctl/kernel.rst? diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst index 1d56a6b73a4e..5d9193bd8d27 100644 --- a/Documentation/admin-guide/sysctl/kernel.rst +++ b/Documentation/admin-guide/sysctl/kernel.rst @@ -1087,6 +1087,13 @@ Model available). If your platform happens to meet the requirements for EAS but you do not want to use it, change this value to 0. +sched_delayacct +=============== + +Enables/disables task delay accounting (see +:doc:`accounting/delay-accounting.rst`). Enabling this feature incurs +a small amount of overhead in the scheduler but is useful for debugging +and performance tuning. It is required by some tools such as iotop. sched_schedstats ================
--- a/Documentation/accounting/delay-accounting.rst +++ b/Documentation/accounting/delay-accounting.rst @@ -74,8 +74,10 @@ Delay accounting is disabled by default delayacct -to the kernel boot options. The rest of the instructions -below assume this has been done. +to the kernel boot options. The rest of the instructions below assume this has +been done. Alternatively, use sysctl kernel.sched_delayacct to switch the state +at runtime. Note however that only tasks started after enabling it will have +delayacct information. After the system has booted up, use a utility similar to getdelays.c to access the delays --- 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) { --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -71,6 +71,7 @@ #include <linux/coredump.h> #include <linux/latencytop.h> #include <linux/pid.h> +#include <linux/delayacct.h> #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 = "sched_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",
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> --- Documentation/accounting/delay-accounting.rst | 6 ++-- kernel/delayacct.c | 36 ++++++++++++++++++++++++-- kernel/sysctl.c | 12 ++++++++ 3 files changed, 50 insertions(+), 4 deletions(-)