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 UPDATE_DELAY(type) \ 18 do { \ 19 d->type##_delay_max = tsk->delays->type##_delay_max; \ 20 d->type##_delay_min = tsk->delays->type##_delay_min; \ 21 d->type##_delay_max_ts.tv_sec = tsk->delays->type##_delay_max_ts.tv_sec; \ 22 d->type##_delay_max_ts.tv_nsec = tsk->delays->type##_delay_max_ts.tv_nsec; \ 23 tmp = d->type##_delay_total + tsk->delays->type##_delay; \ 24 d->type##_delay_total = (tmp < d->type##_delay_total) ? 0 : tmp; \ 25 d->type##_count += tsk->delays->type##_count; \ 26 } while (0) 27 28 DEFINE_STATIC_KEY_FALSE(delayacct_key); 29 int delayacct_on __read_mostly; /* Delay accounting turned on/off */ 30 struct kmem_cache *delayacct_cache; 31 32 static void set_delayacct(bool enabled) 33 { 34 if (enabled) { 35 static_branch_enable(&delayacct_key); 36 delayacct_on = 1; 37 } else { 38 delayacct_on = 0; 39 static_branch_disable(&delayacct_key); 40 } 41 } 42 43 static int __init delayacct_setup_enable(char *str) 44 { 45 delayacct_on = 1; 46 return 1; 47 } 48 __setup("delayacct", delayacct_setup_enable); 49 50 void delayacct_init(void) 51 { 52 delayacct_cache = KMEM_CACHE(task_delay_info, SLAB_PANIC|SLAB_ACCOUNT); 53 delayacct_tsk_init(&init_task); 54 set_delayacct(delayacct_on); 55 } 56 57 #ifdef CONFIG_PROC_SYSCTL 58 static int sysctl_delayacct(const struct ctl_table *table, int write, void *buffer, 59 size_t *lenp, loff_t *ppos) 60 { 61 int state = delayacct_on; 62 struct ctl_table t; 63 int err; 64 65 if (write && !capable(CAP_SYS_ADMIN)) 66 return -EPERM; 67 68 t = *table; 69 t.data = &state; 70 err = proc_dointvec_minmax(&t, write, buffer, lenp, ppos); 71 if (err < 0) 72 return err; 73 if (write) 74 set_delayacct(state); 75 return err; 76 } 77 78 static const struct ctl_table kern_delayacct_table[] = { 79 { 80 .procname = "task_delayacct", 81 .data = NULL, 82 .maxlen = sizeof(unsigned int), 83 .mode = 0644, 84 .proc_handler = sysctl_delayacct, 85 .extra1 = SYSCTL_ZERO, 86 .extra2 = SYSCTL_ONE, 87 }, 88 }; 89 90 static __init int kernel_delayacct_sysctls_init(void) 91 { 92 register_sysctl_init("kernel", kern_delayacct_table); 93 return 0; 94 } 95 late_initcall(kernel_delayacct_sysctls_init); 96 #endif 97 98 void __delayacct_tsk_init(struct task_struct *tsk) 99 { 100 tsk->delays = kmem_cache_zalloc(delayacct_cache, GFP_KERNEL); 101 if (tsk->delays) 102 raw_spin_lock_init(&tsk->delays->lock); 103 } 104 105 /* 106 * Finish delay accounting for a statistic using its timestamps (@start), 107 * accumulator (@total) and @count 108 */ 109 static void delayacct_end(raw_spinlock_t *lock, u64 *start, u64 *total, u32 *count, 110 u64 *max, u64 *min, struct timespec64 *ts) 111 { 112 s64 ns = local_clock() - *start; 113 unsigned long flags; 114 115 if (ns > 0) { 116 raw_spin_lock_irqsave(lock, flags); 117 *total += ns; 118 (*count)++; 119 if (ns > *max) { 120 *max = ns; 121 ktime_get_real_ts64(ts); 122 } 123 if (*min == 0 || ns < *min) 124 *min = ns; 125 raw_spin_unlock_irqrestore(lock, flags); 126 } 127 } 128 129 void __delayacct_blkio_start(void) 130 { 131 current->delays->blkio_start = local_clock(); 132 } 133 134 /* 135 * We cannot rely on the `current` macro, as we haven't yet switched back to 136 * the process being woken. 137 */ 138 void __delayacct_blkio_end(struct task_struct *p) 139 { 140 delayacct_end(&p->delays->lock, 141 &p->delays->blkio_start, 142 &p->delays->blkio_delay, 143 &p->delays->blkio_count, 144 &p->delays->blkio_delay_max, 145 &p->delays->blkio_delay_min, 146 &p->delays->blkio_delay_max_ts); 147 } 148 149 int delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk) 150 { 151 u64 utime, stime, stimescaled, utimescaled; 152 unsigned long long t2, t3; 153 unsigned long flags, t1; 154 s64 tmp; 155 156 task_cputime(tsk, &utime, &stime); 157 tmp = (s64)d->cpu_run_real_total; 158 tmp += utime + stime; 159 d->cpu_run_real_total = (tmp < (s64)d->cpu_run_real_total) ? 0 : tmp; 160 161 task_cputime_scaled(tsk, &utimescaled, &stimescaled); 162 tmp = (s64)d->cpu_scaled_run_real_total; 163 tmp += utimescaled + stimescaled; 164 d->cpu_scaled_run_real_total = 165 (tmp < (s64)d->cpu_scaled_run_real_total) ? 0 : tmp; 166 167 /* 168 * No locking available for sched_info (and too expensive to add one) 169 * Mitigate by taking snapshot of values 170 */ 171 t1 = tsk->sched_info.pcount; 172 t2 = tsk->sched_info.run_delay; 173 t3 = tsk->se.sum_exec_runtime; 174 175 d->cpu_count += t1; 176 177 d->cpu_delay_max = tsk->sched_info.max_run_delay; 178 d->cpu_delay_min = tsk->sched_info.min_run_delay; 179 d->cpu_delay_max_ts.tv_sec = tsk->sched_info.max_run_delay_ts.tv_sec; 180 d->cpu_delay_max_ts.tv_nsec = tsk->sched_info.max_run_delay_ts.tv_nsec; 181 tmp = (s64)d->cpu_delay_total + t2; 182 d->cpu_delay_total = (tmp < (s64)d->cpu_delay_total) ? 0 : tmp; 183 tmp = (s64)d->cpu_run_virtual_total + t3; 184 185 d->cpu_run_virtual_total = 186 (tmp < (s64)d->cpu_run_virtual_total) ? 0 : tmp; 187 188 if (!tsk->delays) 189 return 0; 190 191 /* zero XXX_total, non-zero XXX_count implies XXX stat overflowed */ 192 raw_spin_lock_irqsave(&tsk->delays->lock, flags); 193 UPDATE_DELAY(blkio); 194 UPDATE_DELAY(swapin); 195 UPDATE_DELAY(freepages); 196 UPDATE_DELAY(thrashing); 197 UPDATE_DELAY(compact); 198 UPDATE_DELAY(wpcopy); 199 UPDATE_DELAY(irq); 200 raw_spin_unlock_irqrestore(&tsk->delays->lock, flags); 201 202 return 0; 203 } 204 205 __u64 __delayacct_blkio_ticks(struct task_struct *tsk) 206 { 207 __u64 ret; 208 unsigned long flags; 209 210 raw_spin_lock_irqsave(&tsk->delays->lock, flags); 211 ret = nsec_to_clock_t(tsk->delays->blkio_delay); 212 raw_spin_unlock_irqrestore(&tsk->delays->lock, flags); 213 return ret; 214 } 215 216 void __delayacct_freepages_start(void) 217 { 218 current->delays->freepages_start = local_clock(); 219 } 220 221 void __delayacct_freepages_end(void) 222 { 223 delayacct_end(¤t->delays->lock, 224 ¤t->delays->freepages_start, 225 ¤t->delays->freepages_delay, 226 ¤t->delays->freepages_count, 227 ¤t->delays->freepages_delay_max, 228 ¤t->delays->freepages_delay_min, 229 ¤t->delays->freepages_delay_max_ts); 230 } 231 232 void __delayacct_thrashing_start(bool *in_thrashing) 233 { 234 *in_thrashing = !!current->in_thrashing; 235 if (*in_thrashing) 236 return; 237 238 current->in_thrashing = 1; 239 current->delays->thrashing_start = local_clock(); 240 } 241 242 void __delayacct_thrashing_end(bool *in_thrashing) 243 { 244 if (*in_thrashing) 245 return; 246 247 current->in_thrashing = 0; 248 delayacct_end(¤t->delays->lock, 249 ¤t->delays->thrashing_start, 250 ¤t->delays->thrashing_delay, 251 ¤t->delays->thrashing_count, 252 ¤t->delays->thrashing_delay_max, 253 ¤t->delays->thrashing_delay_min, 254 ¤t->delays->thrashing_delay_max_ts); 255 } 256 257 void __delayacct_swapin_start(void) 258 { 259 current->delays->swapin_start = local_clock(); 260 } 261 262 void __delayacct_swapin_end(void) 263 { 264 delayacct_end(¤t->delays->lock, 265 ¤t->delays->swapin_start, 266 ¤t->delays->swapin_delay, 267 ¤t->delays->swapin_count, 268 ¤t->delays->swapin_delay_max, 269 ¤t->delays->swapin_delay_min, 270 ¤t->delays->swapin_delay_max_ts); 271 } 272 273 void __delayacct_compact_start(void) 274 { 275 current->delays->compact_start = local_clock(); 276 } 277 278 void __delayacct_compact_end(void) 279 { 280 delayacct_end(¤t->delays->lock, 281 ¤t->delays->compact_start, 282 ¤t->delays->compact_delay, 283 ¤t->delays->compact_count, 284 ¤t->delays->compact_delay_max, 285 ¤t->delays->compact_delay_min, 286 ¤t->delays->compact_delay_max_ts); 287 } 288 289 void __delayacct_wpcopy_start(void) 290 { 291 current->delays->wpcopy_start = local_clock(); 292 } 293 294 void __delayacct_wpcopy_end(void) 295 { 296 delayacct_end(¤t->delays->lock, 297 ¤t->delays->wpcopy_start, 298 ¤t->delays->wpcopy_delay, 299 ¤t->delays->wpcopy_count, 300 ¤t->delays->wpcopy_delay_max, 301 ¤t->delays->wpcopy_delay_min, 302 ¤t->delays->wpcopy_delay_max_ts); 303 } 304 305 void __delayacct_irq(struct task_struct *task, u32 delta) 306 { 307 unsigned long flags; 308 309 raw_spin_lock_irqsave(&task->delays->lock, flags); 310 task->delays->irq_delay += delta; 311 task->delays->irq_count++; 312 if (delta > task->delays->irq_delay_max) { 313 task->delays->irq_delay_max = delta; 314 ktime_get_real_ts64(&task->delays->irq_delay_max_ts); 315 } 316 if (delta && (!task->delays->irq_delay_min || delta < task->delays->irq_delay_min)) 317 task->delays->irq_delay_min = delta; 318 raw_spin_unlock_irqrestore(&task->delays->lock, flags); 319 } 320 321