LXR linux/kernel/delayacct.c

   1/* delayacct.c - per-task delay accounting
   2 *
   3 * Copyright (C) Shailabh Nagar, IBM Corp. 2006
   4 *
   5 * This program is free software;  you can redistribute it and/or modify
   6 * it under the terms of the GNU General Public License as published by
   7 * the Free Software Foundation; either version 2 of the License, or
   8 * (at your option) any later version.
   9 *
  10 * This program is distributed in the hope that it would be useful, but
  11 * WITHOUT ANY WARRANTY; without even the implied warranty of
  12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
  13 * the GNU General Public License for more details.
  14 */
  15
  16#include <linux/sched.h>
  17#include <linux/slab.h>
  18#include <linux/taskstats.h>
  19#include <linux/time.h>
  20#include <linux/sysctl.h>
  21#include <linux/delayacct.h>
  22#include <linux/module.h>
  23
  24int delayacct_on __read_mostly = 1;     /* Delay accounting turned on/off */
  25EXPORT_SYMBOL_GPL(delayacct_on);
  26struct kmem_cache *delayacct_cache;
  27
  28static int __init delayacct_setup_disable(char *str)
  29{
  30        delayacct_on = 0;
  31        return 1;
  32}
  33__setup("nodelayacct", delayacct_setup_disable);
  34
  35void delayacct_init(void)
  36{
  37        delayacct_cache = KMEM_CACHE(task_delay_info, SLAB_PANIC|SLAB_ACCOUNT);
  38        delayacct_tsk_init(&init_task);
  39}
  40
  41void __delayacct_tsk_init(struct task_struct *tsk)
  42{
  43        tsk->delays = kmem_cache_zalloc(delayacct_cache, GFP_KERNEL);
  44        if (tsk->delays)
  45                spin_lock_init(&tsk->delays->lock);
  46}
  47
  48/*
  49 * Finish delay accounting for a statistic using its timestamps (@start),
  50 * accumalator (@total) and @count
  51 */
  52static void delayacct_end(u64 *start, u64 *total, u32 *count)
  53{
  54        s64 ns = ktime_get_ns() - *start;
  55        unsigned long flags;
  56
  57        if (ns > 0) {
  58                spin_lock_irqsave(&current->delays->lock, flags);
  59                *total += ns;
  60                (*count)++;
  61                spin_unlock_irqrestore(&current->delays->lock, flags);
  62        }
  63}
  64
  65void __delayacct_blkio_start(void)
  66{
  67        current->delays->blkio_start = ktime_get_ns();
  68}
  69
  70void __delayacct_blkio_end(void)
  71{
  72        if (current->delays->flags & DELAYACCT_PF_SWAPIN)
  73                /* Swapin block I/O */
  74                delayacct_end(&current->delays->blkio_start,
  75                        &current->delays->swapin_delay,
  76                        &current->delays->swapin_count);
  77        else    /* Other block I/O */
  78                delayacct_end(&current->delays->blkio_start,
  79                        &current->delays->blkio_delay,
  80                        &current->delays->blkio_count);
  81}
  82
  83int __delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk)
  84{
  85        cputime_t utime, stime, stimescaled, utimescaled;
  86        unsigned long long t2, t3;
  87        unsigned long flags, t1;
  88        s64 tmp;
  89
  90        task_cputime(tsk, &utime, &stime);
  91        tmp = (s64)d->cpu_run_real_total;
  92        tmp += cputime_to_nsecs(utime + stime);
  93        d->cpu_run_real_total = (tmp < (s64)d->cpu_run_real_total) ? 0 : tmp;
  94
  95        task_cputime_scaled(tsk, &utimescaled, &stimescaled);
  96        tmp = (s64)d->cpu_scaled_run_real_total;
  97        tmp += cputime_to_nsecs(utimescaled + stimescaled);
  98        d->cpu_scaled_run_real_total =
  99                (tmp < (s64)d->cpu_scaled_run_real_total) ? 0 : tmp;
 100
 101        /*
 102         * No locking available for sched_info (and too expensive to add one)
 103         * Mitigate by taking snapshot of values
 104         */
 105        t1 = tsk->sched_info.pcount;
 106        t2 = tsk->sched_info.run_delay;
 107        t3 = tsk->se.sum_exec_runtime;
 108
 109        d->cpu_count += t1;
 110
 111        tmp = (s64)d->cpu_delay_total + t2;
 112        d->cpu_delay_total = (tmp < (s64)d->cpu_delay_total) ? 0 : tmp;
 113
 114        tmp = (s64)d->cpu_run_virtual_total + t3;
 115        d->cpu_run_virtual_total =
 116                (tmp < (s64)d->cpu_run_virtual_total) ? 0 : tmp;
 117
 118        /* zero XXX_total, non-zero XXX_count implies XXX stat overflowed */
 119
 120        spin_lock_irqsave(&tsk->delays->lock, flags);
 121        tmp = d->blkio_delay_total + tsk->delays->blkio_delay;
 122        d->blkio_delay_total = (tmp < d->blkio_delay_total) ? 0 : tmp;
 123        tmp = d->swapin_delay_total + tsk->delays->swapin_delay;
 124        d->swapin_delay_total = (tmp < d->swapin_delay_total) ? 0 : tmp;
 125        tmp = d->freepages_delay_total + tsk->delays->freepages_delay;
 126        d->freepages_delay_total = (tmp < d->freepages_delay_total) ? 0 : tmp;
 127        d->blkio_count += tsk->delays->blkio_count;
 128        d->swapin_count += tsk->delays->swapin_count;
 129        d->freepages_count += tsk->delays->freepages_count;
 130        spin_unlock_irqrestore(&tsk->delays->lock, flags);
 131
 132        return 0;
 133}
 134
 135__u64 __delayacct_blkio_ticks(struct task_struct *tsk)
 136{
 137        __u64 ret;
 138        unsigned long flags;
 139
 140        spin_lock_irqsave(&tsk->delays->lock, flags);
 141        ret = nsec_to_clock_t(tsk->delays->blkio_delay +
 142                                tsk->delays->swapin_delay);
 143        spin_unlock_irqrestore(&tsk->delays->lock, flags);
 144        return ret;
 145}
 146
 147void __delayacct_freepages_start(void)
 148{
 149        current->delays->freepages_start = ktime_get_ns();
 150}
 151
 152void __delayacct_freepages_end(void)
 153{
 154        delayacct_end(&current->delays->freepages_start,
 155                        &current->delays->freepages_delay,
 156                        &current->delays->freepages_count);
 157}
 158
 159