// 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/slab.h> #include <linux/taskstats.h> #include <linux/time.h> #include <linux/sysctl.h> #include <linux/delayacct.h> #include <linux/module.h> int delayacct_on __read_mostly = 1; /* Delay accounting turned on/off */ EXPORT_SYMBOL_GPL(delayacct_on); struct kmem_cache *delayacct_cache; static int __init delayacct_setup_disable(char *str) { delayacct_on = 0; return 1; } __setup("nodelayacct", delayacct_setup_disable); void delayacct_init(void) { delayacct_cache = KMEM_CACHE(task_delay_info, SLAB_PANIC|SLAB_ACCOUNT); delayacct_tsk_init(&init_task); } 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 = ktime_get_ns() - *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 = ktime_get_ns(); } /* * 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) { struct task_delay_info *delays = p->delays; u64 *total; u32 *count; if (p->delays->flags & DELAYACCT_PF_SWAPIN) { total = &delays->swapin_delay; count = &delays->swapin_count; } else { total = &delays->blkio_delay; count = &delays->blkio_count; } delayacct_end(&delays->lock, &delays->blkio_start, total, 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; /* 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; 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; 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 + tsk->delays->swapin_delay); raw_spin_unlock_irqrestore(&tsk->delays->lock, flags); return ret; } void __delayacct_freepages_start(void) { current->delays->freepages_start = ktime_get_ns(); } 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(void) { current->delays->thrashing_start = ktime_get_ns(); } void __delayacct_thrashing_end(void) { delayacct_end(¤t->delays->lock, ¤t->delays->thrashing_start, ¤t->delays->thrashing_delay, ¤t->delays->thrashing_count); }