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/* 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; /* Delay accounting turned on/off */
kmem_cache_t *delayacct_cache;
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_create("delayacct_cache",
sizeof(struct task_delay_info),
0,
SLAB_PANIC,
NULL, NULL);
delayacct_tsk_init(&init_task);
}
void __delayacct_tsk_init(struct task_struct *tsk)
{
spin_lock_init(&tsk->delays_lock);
/* No need to acquire tsk->delays_lock for allocation here unless
__delayacct_tsk_init called after tsk is attached to tasklist
*/
tsk->delays = kmem_cache_zalloc(delayacct_cache, SLAB_KERNEL);
if (tsk->delays)
spin_lock_init(&tsk->delays->lock);
}
void __delayacct_tsk_exit(struct task_struct *tsk)
{
struct task_delay_info *delays = tsk->delays;
spin_lock(&tsk->delays_lock);
tsk->delays = NULL;
spin_unlock(&tsk->delays_lock);
kmem_cache_free(delayacct_cache, delays);
}
/*
* 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;
do_posix_clock_monotonic_gettime(end);
ts = timespec_sub(*end, *start);
ns = timespec_to_ns(&ts);
if (ns < 0)
return;
spin_lock(¤t->delays->lock);
*total += ns;
(*count)++;
spin_unlock(¤t->delays->lock);
}
void __delayacct_blkio_start(void)
{
delayacct_start(¤t->delays->blkio_start);
}
void __delayacct_blkio_end(void)
{
if (current->delays->flags & DELAYACCT_PF_SWAPIN)
/* Swapin block I/O */
delayacct_end(¤t->delays->blkio_start,
¤t->delays->blkio_end,
¤t->delays->swapin_delay,
¤t->delays->swapin_count);
else /* Other block I/O */
delayacct_end(¤t->delays->blkio_start,
¤t->delays->blkio_end,
¤t->delays->blkio_delay,
¤t->delays->blkio_count);
}
int __delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk)
{
s64 tmp;
struct timespec ts;
unsigned long t1,t2,t3;
spin_lock(&tsk->delays_lock);
/* 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;
/*
* No locking available for sched_info (and too expensive to add one)
* Mitigate by taking snapshot of values
*/
t1 = tsk->sched_info.pcnt;
t2 = tsk->sched_info.run_delay;
t3 = tsk->sched_info.cpu_time;
d->cpu_count += t1;
jiffies_to_timespec(t2, &ts);
tmp = (s64)d->cpu_delay_total + timespec_to_ns(&ts);
d->cpu_delay_total = (tmp < (s64)d->cpu_delay_total) ? 0 : tmp;
tmp = (s64)d->cpu_run_virtual_total + (s64)jiffies_to_usecs(t3) * 1000;
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(&tsk->delays->lock);
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(&tsk->delays->lock);
done:
spin_unlock(&tsk->delays_lock);
return 0;
}
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