/* 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/slab.h>#include <linux/time.h>#include <linux/sysctl.h>#include <linux/delayacct.h> int delayacct_on __read_mostly = 1;	/* Delay accounting turned on/off */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);	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);} /* * Start accounting for a delay statistic using * its starting timestamp (@start) */ static inline void delayacct_start(struct timespec *start){	do_posix_clock_monotonic_gettime(start);} /* * Finish delay accounting for a statistic using * its timestamps (@start, @end), accumalator (@total) and @count */ static void delayacct_end(struct timespec *start, struct timespec *end,				u64 *total, u32 *count){	struct timespec ts;	s64 ns;	unsigned long flags; 	do_posix_clock_monotonic_gettime(end);	ts = timespec_sub(*end, *start);	ns = timespec_to_ns(&ts);	if (ns < 0)		return; 	spin_lock_irqsave(&current->delays->lock, flags);	*total += ns;	(*count)++;	spin_unlock_irqrestore(&current->delays->lock, flags);} void __delayacct_blkio_start(void){	delayacct_start(&current->delays->blkio_start);} void __delayacct_blkio_end(void){	if (current->delays->flags & DELAYACCT_PF_SWAPIN)		/* Swapin block I/O */		delayacct_end(&current->delays->blkio_start,			&current->delays->blkio_end,			&current->delays->swapin_delay,			&current->delays->swapin_count);	else	/* Other block I/O */		delayacct_end(&current->delays->blkio_start,			&current->delays->blkio_end,			&current->delays->blkio_delay,			&current->delays->blkio_count);} int __delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk){	s64 tmp;	unsigned long t1;	unsigned long long t2, t3;	unsigned long flags;	struct timespec ts; 	/* Though tsk->delays accessed later, early exit avoids	 * unnecessary returning of other data	 */	if (!tsk->delays)		goto done; 	tmp = (s64)d->cpu_run_real_total;	cputime_to_timespec(tsk->utime + tsk->stime, &ts);	tmp += timespec_to_ns(&ts);	d->cpu_run_real_total = (tmp < (s64)d->cpu_run_real_total) ? 0 : tmp; 	tmp = (s64)d->cpu_scaled_run_real_total;	cputime_to_timespec(tsk->utimescaled + tsk->stimescaled, &ts);	tmp += timespec_to_ns(&ts);	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->sched_info.cpu_time; 	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;	d->blkio_count += tsk->delays->blkio_count;	d->swapin_count += tsk->delays->swapin_count;	spin_unlock_irqrestore(&tsk->delays->lock, flags); done:	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;}