kernel/delayacct.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* delayacct.c - per-task delay accounting
   3  *
   4  * Copyright (C) Shailabh Nagar, IBM Corp. 2006
   5  */
   6
   7 #include <linux/sched.h>
   8 #include <linux/sched/task.h>
   9 #include <linux/sched/cputime.h>
  10 #include <linux/sched/clock.h>
  11 #include <linux/slab.h>
  12 #include <linux/taskstats.h>
  13 #include <linux/sysctl.h>
  14 #include <linux/delayacct.h>
  15 #include <linux/module.h>
  16
  17 DEFINE_STATIC_KEY_FALSE(delayacct_key);
  18 int delayacct_on __read_mostly; /* Delay accounting turned on/off */
  19 struct kmem_cache *delayacct_cache;
  20
  21 static void set_delayacct(bool enabled)
  22 {
  23         if (enabled) {
  24                 static_branch_enable(&delayacct_key);
  25                 delayacct_on = 1;
  26         } else {
  27                 delayacct_on = 0;
  28                 static_branch_disable(&delayacct_key);
  29         }
  30 }
  31
  32 static int __init delayacct_setup_enable(char *str)
  33 {
  34         delayacct_on = 1;
  35         return 1;
  36 }
  37 __setup("delayacct", delayacct_setup_enable);
  38
  39 void delayacct_init(void)
  40 {
  41         delayacct_cache = KMEM_CACHE(task_delay_info, SLAB_PANIC|SLAB_ACCOUNT);
  42         delayacct_tsk_init(&init_task);
  43         set_delayacct(delayacct_on);
  44 }
  45
  46 #ifdef CONFIG_PROC_SYSCTL
  47 static int sysctl_delayacct(struct ctl_table *table, int write, void *buffer,
  48                      size_t *lenp, loff_t *ppos)
  49 {
  50         int state = delayacct_on;
  51         struct ctl_table t;
  52         int err;
  53
  54         if (write && !capable(CAP_SYS_ADMIN))
  55                 return -EPERM;
  56
  57         t = *table;
  58         t.data = &state;
  59         err = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
  60         if (err < 0)
  61                 return err;
  62         if (write)
  63                 set_delayacct(state);
  64         return err;
  65 }
  66
  67 static struct ctl_table kern_delayacct_table[] = {
  68         {
  69                 .procname       = "task_delayacct",
  70                 .data           = NULL,
  71                 .maxlen         = sizeof(unsigned int),
  72                 .mode           = 0644,
  73                 .proc_handler   = sysctl_delayacct,
  74                 .extra1         = SYSCTL_ZERO,
  75                 .extra2         = SYSCTL_ONE,
  76         },
  77 };
  78
  79 static __init int kernel_delayacct_sysctls_init(void)
  80 {
  81         register_sysctl_init("kernel", kern_delayacct_table);
  82         return 0;
  83 }
  84 late_initcall(kernel_delayacct_sysctls_init);
  85 #endif
  86
  87 void __delayacct_tsk_init(struct task_struct *tsk)
  88 {
  89         tsk->delays = kmem_cache_zalloc(delayacct_cache, GFP_KERNEL);
  90         if (tsk->delays)
  91                 raw_spin_lock_init(&tsk->delays->lock);
  92 }
  93
  94 /*
  95  * Finish delay accounting for a statistic using its timestamps (@start),
  96  * accumalator (@total) and @count
  97  */
  98 static void delayacct_end(raw_spinlock_t *lock, u64 *start, u64 *total, u32 *count)
  99 {
 100         s64 ns = local_clock() - *start;
 101         unsigned long flags;
 102
 103         if (ns > 0) {
 104                 raw_spin_lock_irqsave(lock, flags);
 105                 *total += ns;
 106                 (*count)++;
 107                 raw_spin_unlock_irqrestore(lock, flags);
 108         }
 109 }
 110
 111 void __delayacct_blkio_start(void)
 112 {
 113         current->delays->blkio_start = local_clock();
 114 }
 115
 116 /*
 117  * We cannot rely on the `current` macro, as we haven't yet switched back to
 118  * the process being woken.
 119  */
 120 void __delayacct_blkio_end(struct task_struct *p)
 121 {
 122         delayacct_end(&p->delays->lock,
 123                       &p->delays->blkio_start,
 124                       &p->delays->blkio_delay,
 125                       &p->delays->blkio_count);
 126 }
 127
 128 int delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk)
 129 {
 130         u64 utime, stime, stimescaled, utimescaled;
 131         unsigned long long t2, t3;
 132         unsigned long flags, t1;
 133         s64 tmp;
 134
 135         task_cputime(tsk, &utime, &stime);
 136         tmp = (s64)d->cpu_run_real_total;
 137         tmp += utime + stime;
 138         d->cpu_run_real_total = (tmp < (s64)d->cpu_run_real_total) ? 0 : tmp;
 139
 140         task_cputime_scaled(tsk, &utimescaled, &stimescaled);
 141         tmp = (s64)d->cpu_scaled_run_real_total;
 142         tmp += utimescaled + stimescaled;
 143         d->cpu_scaled_run_real_total =
 144                 (tmp < (s64)d->cpu_scaled_run_real_total) ? 0 : tmp;
 145
 146         /*
 147          * No locking available for sched_info (and too expensive to add one)
 148          * Mitigate by taking snapshot of values
 149          */
 150         t1 = tsk->sched_info.pcount;
 151         t2 = tsk->sched_info.run_delay;
 152         t3 = tsk->se.sum_exec_runtime;
 153
 154         d->cpu_count += t1;
 155
 156         tmp = (s64)d->cpu_delay_total + t2;
 157         d->cpu_delay_total = (tmp < (s64)d->cpu_delay_total) ? 0 : tmp;
 158
 159         tmp = (s64)d->cpu_run_virtual_total + t3;
 160         d->cpu_run_virtual_total =
 161                 (tmp < (s64)d->cpu_run_virtual_total) ? 0 : tmp;
 162
 163         if (!tsk->delays)
 164                 return 0;
 165
 166         /* zero XXX_total, non-zero XXX_count implies XXX stat overflowed */
 167
 168         raw_spin_lock_irqsave(&tsk->delays->lock, flags);
 169         tmp = d->blkio_delay_total + tsk->delays->blkio_delay;
 170         d->blkio_delay_total = (tmp < d->blkio_delay_total) ? 0 : tmp;
 171         tmp = d->swapin_delay_total + tsk->delays->swapin_delay;
 172         d->swapin_delay_total = (tmp < d->swapin_delay_total) ? 0 : tmp;
 173         tmp = d->freepages_delay_total + tsk->delays->freepages_delay;
 174         d->freepages_delay_total = (tmp < d->freepages_delay_total) ? 0 : tmp;
 175         tmp = d->thrashing_delay_total + tsk->delays->thrashing_delay;
 176         d->thrashing_delay_total = (tmp < d->thrashing_delay_total) ? 0 : tmp;
 177         tmp = d->compact_delay_total + tsk->delays->compact_delay;
 178         d->compact_delay_total = (tmp < d->compact_delay_total) ? 0 : tmp;
 179         tmp = d->wpcopy_delay_total + tsk->delays->wpcopy_delay;
 180         d->wpcopy_delay_total = (tmp < d->wpcopy_delay_total) ? 0 : tmp;
 181         tmp = d->irq_delay_total + tsk->delays->irq_delay;
 182         d->irq_delay_total = (tmp < d->irq_delay_total) ? 0 : tmp;
 183         d->blkio_count += tsk->delays->blkio_count;
 184         d->swapin_count += tsk->delays->swapin_count;
 185         d->freepages_count += tsk->delays->freepages_count;
 186         d->thrashing_count += tsk->delays->thrashing_count;
 187         d->compact_count += tsk->delays->compact_count;
 188         d->wpcopy_count += tsk->delays->wpcopy_count;
 189         d->irq_count += tsk->delays->irq_count;
 190         raw_spin_unlock_irqrestore(&tsk->delays->lock, flags);
 191
 192         return 0;
 193 }
 194
 195 __u64 __delayacct_blkio_ticks(struct task_struct *tsk)
 196 {
 197         __u64 ret;
 198         unsigned long flags;
 199
 200         raw_spin_lock_irqsave(&tsk->delays->lock, flags);
 201         ret = nsec_to_clock_t(tsk->delays->blkio_delay);
 202         raw_spin_unlock_irqrestore(&tsk->delays->lock, flags);
 203         return ret;
 204 }
 205
 206 void __delayacct_freepages_start(void)
 207 {
 208         current->delays->freepages_start = local_clock();
 209 }
 210
 211 void __delayacct_freepages_end(void)
 212 {
 213         delayacct_end(&current->delays->lock,
 214                       &current->delays->freepages_start,
 215                       &current->delays->freepages_delay,
 216                       &current->delays->freepages_count);
 217 }
 218
 219 void __delayacct_thrashing_start(bool *in_thrashing)
 220 {
 221         *in_thrashing = !!current->in_thrashing;
 222         if (*in_thrashing)
 223                 return;
 224
 225         current->in_thrashing = 1;
 226         current->delays->thrashing_start = local_clock();
 227 }
 228
 229 void __delayacct_thrashing_end(bool *in_thrashing)
 230 {
 231         if (*in_thrashing)
 232                 return;
 233
 234         current->in_thrashing = 0;
 235         delayacct_end(&current->delays->lock,
 236                       &current->delays->thrashing_start,
 237                       &current->delays->thrashing_delay,
 238                       &current->delays->thrashing_count);
 239 }
 240
 241 void __delayacct_swapin_start(void)
 242 {
 243         current->delays->swapin_start = local_clock();
 244 }
 245
 246 void __delayacct_swapin_end(void)
 247 {
 248         delayacct_end(&current->delays->lock,
 249                       &current->delays->swapin_start,
 250                       &current->delays->swapin_delay,
 251                       &current->delays->swapin_count);
 252 }
 253
 254 void __delayacct_compact_start(void)
 255 {
 256         current->delays->compact_start = local_clock();
 257 }
 258
 259 void __delayacct_compact_end(void)
 260 {
 261         delayacct_end(&current->delays->lock,
 262                       &current->delays->compact_start,
 263                       &current->delays->compact_delay,
 264                       &current->delays->compact_count);
 265 }
 266
 267 void __delayacct_wpcopy_start(void)
 268 {
 269         current->delays->wpcopy_start = local_clock();
 270 }
 271
 272 void __delayacct_wpcopy_end(void)
 273 {
 274         delayacct_end(&current->delays->lock,
 275                       &current->delays->wpcopy_start,
 276                       &current->delays->wpcopy_delay,
 277                       &current->delays->wpcopy_count);
 278 }
 279
 280 void __delayacct_irq(struct task_struct *task, u32 delta)
 281 {
 282         unsigned long flags;
 283
 284         raw_spin_lock_irqsave(&task->delays->lock, flags);
 285         task->delays->irq_delay += delta;
 286         task->delays->irq_count++;
 287         raw_spin_unlock_irqrestore(&task->delays->lock, flags);
 288 }
 289