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
  80 static __init int kernel_delayacct_sysctls_init(void)
  81 {
  82         register_sysctl_init("kernel", kern_delayacct_table);
  83         return 0;
  84 }
  85 late_initcall(kernel_delayacct_sysctls_init);
  86 #endif
  87
  88 void __delayacct_tsk_init(struct task_struct *tsk)
  89 {
  90         tsk->delays = kmem_cache_zalloc(delayacct_cache, GFP_KERNEL);
  91         if (tsk->delays)
  92                 raw_spin_lock_init(&tsk->delays->lock);
  93 }
  94
  95 /*
  96  * Finish delay accounting for a statistic using its timestamps (@start),
  97  * accumalator (@total) and @count
  98  */
  99 static void delayacct_end(raw_spinlock_t *lock, u64 *start, u64 *total, u32 *count)
 100 {
 101         s64 ns = local_clock() - *start;
 102         unsigned long flags;
 103
 104         if (ns > 0) {
 105                 raw_spin_lock_irqsave(lock, flags);
 106                 *total += ns;
 107                 (*count)++;
 108                 raw_spin_unlock_irqrestore(lock, flags);
 109         }
 110 }
 111
 112 void __delayacct_blkio_start(void)
 113 {
 114         current->delays->blkio_start = local_clock();
 115 }
 116
 117 /*
 118  * We cannot rely on the `current` macro, as we haven't yet switched back to
 119  * the process being woken.
 120  */
 121 void __delayacct_blkio_end(struct task_struct *p)
 122 {
 123         delayacct_end(&p->delays->lock,
 124                       &p->delays->blkio_start,
 125                       &p->delays->blkio_delay,
 126                       &p->delays->blkio_count);
 127 }
 128
 129 int delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk)
 130 {
 131         u64 utime, stime, stimescaled, utimescaled;
 132         unsigned long long t2, t3;
 133         unsigned long flags, t1;
 134         s64 tmp;
 135
 136         task_cputime(tsk, &utime, &stime);
 137         tmp = (s64)d->cpu_run_real_total;
 138         tmp += utime + stime;
 139         d->cpu_run_real_total = (tmp < (s64)d->cpu_run_real_total) ? 0 : tmp;
 140
 141         task_cputime_scaled(tsk, &utimescaled, &stimescaled);
 142         tmp = (s64)d->cpu_scaled_run_real_total;
 143         tmp += utimescaled + stimescaled;
 144         d->cpu_scaled_run_real_total =
 145                 (tmp < (s64)d->cpu_scaled_run_real_total) ? 0 : tmp;
 146
 147         /*
 148          * No locking available for sched_info (and too expensive to add one)
 149          * Mitigate by taking snapshot of values
 150          */
 151         t1 = tsk->sched_info.pcount;
 152         t2 = tsk->sched_info.run_delay;
 153         t3 = tsk->se.sum_exec_runtime;
 154
 155         d->cpu_count += t1;
 156
 157         tmp = (s64)d->cpu_delay_total + t2;
 158         d->cpu_delay_total = (tmp < (s64)d->cpu_delay_total) ? 0 : tmp;
 159
 160         tmp = (s64)d->cpu_run_virtual_total + t3;
 161         d->cpu_run_virtual_total =
 162                 (tmp < (s64)d->cpu_run_virtual_total) ? 0 : tmp;
 163
 164         if (!tsk->delays)
 165                 return 0;
 166
 167         /* zero XXX_total, non-zero XXX_count implies XXX stat overflowed */
 168
 169         raw_spin_lock_irqsave(&tsk->delays->lock, flags);
 170         tmp = d->blkio_delay_total + tsk->delays->blkio_delay;
 171         d->blkio_delay_total = (tmp < d->blkio_delay_total) ? 0 : tmp;
 172         tmp = d->swapin_delay_total + tsk->delays->swapin_delay;
 173         d->swapin_delay_total = (tmp < d->swapin_delay_total) ? 0 : tmp;
 174         tmp = d->freepages_delay_total + tsk->delays->freepages_delay;
 175         d->freepages_delay_total = (tmp < d->freepages_delay_total) ? 0 : tmp;
 176         tmp = d->thrashing_delay_total + tsk->delays->thrashing_delay;
 177         d->thrashing_delay_total = (tmp < d->thrashing_delay_total) ? 0 : tmp;
 178         tmp = d->compact_delay_total + tsk->delays->compact_delay;
 179         d->compact_delay_total = (tmp < d->compact_delay_total) ? 0 : tmp;
 180         tmp = d->wpcopy_delay_total + tsk->delays->wpcopy_delay;
 181         d->wpcopy_delay_total = (tmp < d->wpcopy_delay_total) ? 0 : tmp;
 182         d->blkio_count += tsk->delays->blkio_count;
 183         d->swapin_count += tsk->delays->swapin_count;
 184         d->freepages_count += tsk->delays->freepages_count;
 185         d->thrashing_count += tsk->delays->thrashing_count;
 186         d->compact_count += tsk->delays->compact_count;
 187         d->wpcopy_count += tsk->delays->wpcopy_count;
 188         raw_spin_unlock_irqrestore(&tsk->delays->lock, flags);
 189
 190         return 0;
 191 }
 192
 193 __u64 __delayacct_blkio_ticks(struct task_struct *tsk)
 194 {
 195         __u64 ret;
 196         unsigned long flags;
 197
 198         raw_spin_lock_irqsave(&tsk->delays->lock, flags);
 199         ret = nsec_to_clock_t(tsk->delays->blkio_delay);
 200         raw_spin_unlock_irqrestore(&tsk->delays->lock, flags);
 201         return ret;
 202 }
 203
 204 void __delayacct_freepages_start(void)
 205 {
 206         current->delays->freepages_start = local_clock();
 207 }
 208
 209 void __delayacct_freepages_end(void)
 210 {
 211         delayacct_end(&current->delays->lock,
 212                       &current->delays->freepages_start,
 213                       &current->delays->freepages_delay,
 214                       &current->delays->freepages_count);
 215 }
 216
 217 void __delayacct_thrashing_start(void)
 218 {
 219         current->delays->thrashing_start = local_clock();
 220 }
 221
 222 void __delayacct_thrashing_end(void)
 223 {
 224         delayacct_end(&current->delays->lock,
 225                       &current->delays->thrashing_start,
 226                       &current->delays->thrashing_delay,
 227                       &current->delays->thrashing_count);
 228 }
 229
 230 void __delayacct_swapin_start(void)
 231 {
 232         current->delays->swapin_start = local_clock();
 233 }
 234
 235 void __delayacct_swapin_end(void)
 236 {
 237         delayacct_end(&current->delays->lock,
 238                       &current->delays->swapin_start,
 239                       &current->delays->swapin_delay,
 240                       &current->delays->swapin_count);
 241 }
 242
 243 void __delayacct_compact_start(void)
 244 {
 245         current->delays->compact_start = local_clock();
 246 }
 247
 248 void __delayacct_compact_end(void)
 249 {
 250         delayacct_end(&current->delays->lock,
 251                       &current->delays->compact_start,
 252                       &current->delays->compact_delay,
 253                       &current->delays->compact_count);
 254 }
 255
 256 void __delayacct_wpcopy_start(void)
 257 {
 258         current->delays->wpcopy_start = local_clock();
 259 }
 260
 261 void __delayacct_wpcopy_end(void)
 262 {
 263         delayacct_end(&current->delays->lock,
 264                       &current->delays->wpcopy_start,
 265                       &current->delays->wpcopy_delay,
 266                       &current->delays->wpcopy_count);
 267 }