linux-imx

/* 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)

        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);

}