/* delayacct.c - per-task delay accounting * * Copyright (C) Shailabh Nagar, IBM Corp. 2006 * * This program is free software;  you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it would be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See * the GNU General Public License for more details. */ #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)		spin_lock_init(&tsk->delays->lock);} /* * Finish delay accounting for a statistic using its timestamps (@start), * accumalator (@total) and @count */static void delayacct_end(spinlock_t *lock, u64 *start, u64 *total, u32 *count){	s64 ns = ktime_get_ns() - *start;	unsigned long flags; 	if (ns > 0) {		spin_lock_irqsave(lock, flags);		*total += ns;		(*count)++;		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 */ 	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;	d->blkio_count += tsk->delays->blkio_count;	d->swapin_count += tsk->delays->swapin_count;	d->freepages_count += tsk->delays->freepages_count;	spin_unlock_irqrestore(&tsk->delays->lock, flags); 	return 0;} __u64 __delayacct_blkio_ticks(struct task_struct *tsk){	__u64 ret;	unsigned long flags; 	spin_lock_irqsave(&tsk->delays->lock, flags);	ret = nsec_to_clock_t(tsk->delays->blkio_delay +				tsk->delays->swapin_delay);	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(		&current->delays->lock,		&current->delays->freepages_start,		&current->delays->freepages_delay,		&current->delays->freepages_count);}