diff options
Diffstat (limited to 'kernel/delayacct.c')
| -rw-r--r-- | kernel/delayacct.c | 290 |
1 files changed, 290 insertions, 0 deletions
diff --git a/kernel/delayacct.c b/kernel/delayacct.c new file mode 100644 index 0000000000..6f0c358e73 --- /dev/null +++ b/kernel/delayacct.c @@ -0,0 +1,290 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* delayacct.c - per-task delay accounting + * + * Copyright (C) Shailabh Nagar, IBM Corp. 2006 + */ + +#include <linux/sched.h> +#include <linux/sched/task.h> +#include <linux/sched/cputime.h> +#include <linux/sched/clock.h> +#include <linux/slab.h> +#include <linux/taskstats.h> +#include <linux/sysctl.h> +#include <linux/delayacct.h> +#include <linux/module.h> + +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; + return 1; +} +__setup("delayacct", delayacct_setup_enable); + +void delayacct_init(void) +{ + delayacct_cache = KMEM_CACHE(task_delay_info, SLAB_PANIC|SLAB_ACCOUNT); + delayacct_tsk_init(&init_task); + set_delayacct(delayacct_on); +} + +#ifdef CONFIG_PROC_SYSCTL +static 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; +} + +static struct ctl_table kern_delayacct_table[] = { + { + .procname = "task_delayacct", + .data = NULL, + .maxlen = sizeof(unsigned int), + .mode = 0644, + .proc_handler = sysctl_delayacct, + .extra1 = SYSCTL_ZERO, + .extra2 = SYSCTL_ONE, + }, + { } +}; + +static __init int kernel_delayacct_sysctls_init(void) +{ + register_sysctl_init("kernel", kern_delayacct_table); + return 0; +} +late_initcall(kernel_delayacct_sysctls_init); +#endif + +void __delayacct_tsk_init(struct task_struct *tsk) +{ + tsk->delays = kmem_cache_zalloc(delayacct_cache, GFP_KERNEL); + if (tsk->delays) + raw_spin_lock_init(&tsk->delays->lock); +} + +/* + * Finish delay accounting for a statistic using its timestamps (@start), + * accumalator (@total) and @count + */ +static void delayacct_end(raw_spinlock_t *lock, u64 *start, u64 *total, u32 *count) +{ + s64 ns = local_clock() - *start; + unsigned long flags; + + if (ns > 0) { + raw_spin_lock_irqsave(lock, flags); + *total += ns; + (*count)++; + raw_spin_unlock_irqrestore(lock, flags); + } +} + +void __delayacct_blkio_start(void) +{ + current->delays->blkio_start = local_clock(); +} + +/* + * We cannot rely on the `current` macro, as we haven't yet switched back to + * the process being woken. + */ +void __delayacct_blkio_end(struct task_struct *p) +{ + delayacct_end(&p->delays->lock, + &p->delays->blkio_start, + &p->delays->blkio_delay, + &p->delays->blkio_count); +} + +int delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk) +{ + u64 utime, stime, stimescaled, utimescaled; + unsigned long long t2, t3; + unsigned long flags, t1; + s64 tmp; + + task_cputime(tsk, &utime, &stime); + tmp = (s64)d->cpu_run_real_total; + tmp += utime + stime; + d->cpu_run_real_total = (tmp < (s64)d->cpu_run_real_total) ? 0 : tmp; + + task_cputime_scaled(tsk, &utimescaled, &stimescaled); + tmp = (s64)d->cpu_scaled_run_real_total; + tmp += utimescaled + stimescaled; + d->cpu_scaled_run_real_total = + (tmp < (s64)d->cpu_scaled_run_real_total) ? 0 : tmp; + + /* + * No locking available for sched_info (and too expensive to add one) + * Mitigate by taking snapshot of values + */ + t1 = tsk->sched_info.pcount; + t2 = tsk->sched_info.run_delay; + t3 = tsk->se.sum_exec_runtime; + + d->cpu_count += t1; + + tmp = (s64)d->cpu_delay_total + t2; + d->cpu_delay_total = (tmp < (s64)d->cpu_delay_total) ? 0 : tmp; + + tmp = (s64)d->cpu_run_virtual_total + t3; + d->cpu_run_virtual_total = + (tmp < (s64)d->cpu_run_virtual_total) ? 0 : tmp; + + if (!tsk->delays) + return 0; + + /* zero XXX_total, non-zero XXX_count implies XXX stat overflowed */ + + raw_spin_lock_irqsave(&tsk->delays->lock, flags); + tmp = d->blkio_delay_total + tsk->delays->blkio_delay; + d->blkio_delay_total = (tmp < d->blkio_delay_total) ? 0 : tmp; + tmp = d->swapin_delay_total + tsk->delays->swapin_delay; + d->swapin_delay_total = (tmp < d->swapin_delay_total) ? 0 : tmp; + tmp = d->freepages_delay_total + tsk->delays->freepages_delay; + d->freepages_delay_total = (tmp < d->freepages_delay_total) ? 0 : tmp; + tmp = d->thrashing_delay_total + tsk->delays->thrashing_delay; + d->thrashing_delay_total = (tmp < d->thrashing_delay_total) ? 0 : tmp; + tmp = d->compact_delay_total + tsk->delays->compact_delay; + d->compact_delay_total = (tmp < d->compact_delay_total) ? 0 : tmp; + tmp = d->wpcopy_delay_total + tsk->delays->wpcopy_delay; + d->wpcopy_delay_total = (tmp < d->wpcopy_delay_total) ? 0 : tmp; + tmp = d->irq_delay_total + tsk->delays->irq_delay; + d->irq_delay_total = (tmp < d->irq_delay_total) ? 0 : tmp; + d->blkio_count += tsk->delays->blkio_count; + d->swapin_count += tsk->delays->swapin_count; + d->freepages_count += tsk->delays->freepages_count; + d->thrashing_count += tsk->delays->thrashing_count; + d->compact_count += tsk->delays->compact_count; + d->wpcopy_count += tsk->delays->wpcopy_count; + d->irq_count += tsk->delays->irq_count; + raw_spin_unlock_irqrestore(&tsk->delays->lock, flags); + + return 0; +} + +__u64 __delayacct_blkio_ticks(struct task_struct *tsk) +{ + __u64 ret; + unsigned long flags; + + raw_spin_lock_irqsave(&tsk->delays->lock, flags); + ret = nsec_to_clock_t(tsk->delays->blkio_delay); + raw_spin_unlock_irqrestore(&tsk->delays->lock, flags); + return ret; +} + +void __delayacct_freepages_start(void) +{ + current->delays->freepages_start = local_clock(); +} + +void __delayacct_freepages_end(void) +{ + delayacct_end(¤t->delays->lock, + ¤t->delays->freepages_start, + ¤t->delays->freepages_delay, + ¤t->delays->freepages_count); +} + +void __delayacct_thrashing_start(bool *in_thrashing) +{ + *in_thrashing = !!current->in_thrashing; + if (*in_thrashing) + return; + + current->in_thrashing = 1; + current->delays->thrashing_start = local_clock(); +} + +void __delayacct_thrashing_end(bool *in_thrashing) +{ + if (*in_thrashing) + return; + + current->in_thrashing = 0; + delayacct_end(¤t->delays->lock, + ¤t->delays->thrashing_start, + ¤t->delays->thrashing_delay, + ¤t->delays->thrashing_count); +} + +void __delayacct_swapin_start(void) +{ + current->delays->swapin_start = local_clock(); +} + +void __delayacct_swapin_end(void) +{ + delayacct_end(¤t->delays->lock, + ¤t->delays->swapin_start, + ¤t->delays->swapin_delay, + ¤t->delays->swapin_count); +} + +void __delayacct_compact_start(void) +{ + current->delays->compact_start = local_clock(); +} + +void __delayacct_compact_end(void) +{ + delayacct_end(¤t->delays->lock, + ¤t->delays->compact_start, + ¤t->delays->compact_delay, + ¤t->delays->compact_count); +} + +void __delayacct_wpcopy_start(void) +{ + current->delays->wpcopy_start = local_clock(); +} + +void __delayacct_wpcopy_end(void) +{ + delayacct_end(¤t->delays->lock, + ¤t->delays->wpcopy_start, + ¤t->delays->wpcopy_delay, + ¤t->delays->wpcopy_count); +} + +void __delayacct_irq(struct task_struct *task, u32 delta) +{ + unsigned long flags; + + raw_spin_lock_irqsave(&task->delays->lock, flags); + task->delays->irq_delay += delta; + task->delays->irq_count++; + raw_spin_unlock_irqrestore(&task->delays->lock, flags); +} + |