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
  24 int delayacct_on __read_mostly = 1;     /* Delay accounting turned on/off */
  25 EXPORT_SYMBOL_GPL(delayacct_on);
  26 struct kmem_cache *delayacct_cache;
  27
  28 static int __init delayacct_setup_disable(char *str)
  29 {
  30         delayacct_on = 0;
  31         return 1;
  32 }
  33 __setup("nodelayacct", delayacct_setup_disable);
  34
  35 void delayacct_init(void)
  36 {
  37         delayacct_cache = KMEM_CACHE(task_delay_info, SLAB_PANIC);
  38         delayacct_tsk_init(&init_task);
  39 }
  40
  41 void __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
  50  * its timestamps (@start, @end), accumalator (@total) and @count
  51  */
  52
  53 static void delayacct_end(struct timespec *start, struct timespec *end,
  54                                 u64 *total, u32 *count)
  55 {
  56         struct timespec ts;
  57         s64 ns;
  58         unsigned long flags;
  59
  60         ktime_get_ts(end);
  61         ts = timespec_sub(*end, *start);
  62         ns = timespec_to_ns(&ts);
  63         if (ns < 0)
  64                 return;
  65
  66         spin_lock_irqsave(&current->delays->lock, flags);
  67         *total += ns;
  68         (*count)++;
  69         spin_unlock_irqrestore(&current->delays->lock, flags);
  70 }
  71
  72 void __delayacct_blkio_start(void)
  73 {
  74         ktime_get_ts(&current->delays->blkio_start);
  75 }
  76
  77 void __delayacct_blkio_end(void)
  78 {
  79         if (current->delays->flags & DELAYACCT_PF_SWAPIN)
  80                 /* Swapin block I/O */
  81                 delayacct_end(&current->delays->blkio_start,
  82                         &current->delays->blkio_end,
  83                         &current->delays->swapin_delay,
  84                         &current->delays->swapin_count);
  85         else    /* Other block I/O */
  86                 delayacct_end(&current->delays->blkio_start,
  87                         &current->delays->blkio_end,
  88                         &current->delays->blkio_delay,
  89                         &current->delays->blkio_count);
  90 }
  91
  92 int __delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk)
  93 {
  94         s64 tmp;
  95         unsigned long t1;
  96         unsigned long long t2, t3;
  97         unsigned long flags;
  98         struct timespec ts;
  99         cputime_t utime, stime, stimescaled, utimescaled;
 100
 101         tmp = (s64)d->cpu_run_real_total;
 102         task_cputime(tsk, &utime, &stime);
 103         cputime_to_timespec(utime + stime, &ts);
 104         tmp += timespec_to_ns(&ts);
 105         d->cpu_run_real_total = (tmp < (s64)d->cpu_run_real_total) ? 0 : tmp;
 106
 107         tmp = (s64)d->cpu_scaled_run_real_total;
 108         task_cputime_scaled(tsk, &utimescaled, &stimescaled);
 109         cputime_to_timespec(utimescaled + stimescaled, &ts);
 110         tmp += timespec_to_ns(&ts);
 111         d->cpu_scaled_run_real_total =
 112                 (tmp < (s64)d->cpu_scaled_run_real_total) ? 0 : tmp;
 113
 114         /*
 115          * No locking available for sched_info (and too expensive to add one)
 116          * Mitigate by taking snapshot of values
 117          */
 118         t1 = tsk->sched_info.pcount;
 119         t2 = tsk->sched_info.run_delay;
 120         t3 = tsk->se.sum_exec_runtime;
 121
 122         d->cpu_count += t1;
 123
 124         tmp = (s64)d->cpu_delay_total + t2;
 125         d->cpu_delay_total = (tmp < (s64)d->cpu_delay_total) ? 0 : tmp;
 126
 127         tmp = (s64)d->cpu_run_virtual_total + t3;
 128         d->cpu_run_virtual_total =
 129                 (tmp < (s64)d->cpu_run_virtual_total) ? 0 : tmp;
 130
 131         /* zero XXX_total, non-zero XXX_count implies XXX stat overflowed */
 132
 133         spin_lock_irqsave(&tsk->delays->lock, flags);
 134         tmp = d->blkio_delay_total + tsk->delays->blkio_delay;
 135         d->blkio_delay_total = (tmp < d->blkio_delay_total) ? 0 : tmp;
 136         tmp = d->swapin_delay_total + tsk->delays->swapin_delay;
 137         d->swapin_delay_total = (tmp < d->swapin_delay_total) ? 0 : tmp;
 138         tmp = d->freepages_delay_total + tsk->delays->freepages_delay;
 139         d->freepages_delay_total = (tmp < d->freepages_delay_total) ? 0 : tmp;
 140         d->blkio_count += tsk->delays->blkio_count;
 141         d->swapin_count += tsk->delays->swapin_count;
 142         d->freepages_count += tsk->delays->freepages_count;
 143         spin_unlock_irqrestore(&tsk->delays->lock, flags);
 144
 145         return 0;
 146 }
 147
 148 __u64 __delayacct_blkio_ticks(struct task_struct *tsk)
 149 {
 150         __u64 ret;
 151         unsigned long flags;
 152
 153         spin_lock_irqsave(&tsk->delays->lock, flags);
 154         ret = nsec_to_clock_t(tsk->delays->blkio_delay +
 155                                 tsk->delays->swapin_delay);
 156         spin_unlock_irqrestore(&tsk->delays->lock, flags);
 157         return ret;
 158 }
 159
 160 void __delayacct_freepages_start(void)
 161 {
 162         ktime_get_ts(&current->delays->freepages_start);
 163 }
 164
 165 void __delayacct_freepages_end(void)
 166 {
 167         delayacct_end(&current->delays->freepages_start,
 168                         &current->delays->freepages_end,
 169                         &current->delays->freepages_delay,
 170                         &current->delays->freepages_count);
 171 }
 172