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(const 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 * accumulator (@total) and @count 97 */ 98 static void delayacct_end(raw_spinlock_t *lock, u64 *start, u64 *total, u32 *count, u64 *max) 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 if (ns > *max) 108 *max = ns; 109 raw_spin_unlock_irqrestore(lock, flags); 110 } 111 } 112 113 void __delayacct_blkio_start(void) 114 { 115 current->delays->blkio_start = local_clock(); 116 } 117 118 /* 119 * We cannot rely on the `current` macro, as we haven't yet switched back to 120 * the process being woken. 121 */ 122 void __delayacct_blkio_end(struct task_struct *p) 123 { 124 delayacct_end(&p->delays->lock, 125 &p->delays->blkio_start, 126 &p->delays->blkio_delay, 127 &p->delays->blkio_count, 128 &p->delays->blkio_delay_max); 129 } 130 131 int delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk) 132 { 133 u64 utime, stime, stimescaled, utimescaled; 134 unsigned long long t2, t3; 135 unsigned long flags, t1; 136 s64 tmp; 137 138 task_cputime(tsk, &utime, &stime); 139 tmp = (s64)d->cpu_run_real_total; 140 tmp += utime + stime; 141 d->cpu_run_real_total = (tmp < (s64)d->cpu_run_real_total) ? 0 : tmp; 142 143 task_cputime_scaled(tsk, &utimescaled, &stimescaled); 144 tmp = (s64)d->cpu_scaled_run_real_total; 145 tmp += utimescaled + stimescaled; 146 d->cpu_scaled_run_real_total = 147 (tmp < (s64)d->cpu_scaled_run_real_total) ? 0 : tmp; 148 149 /* 150 * No locking available for sched_info (and too expensive to add one) 151 * Mitigate by taking snapshot of values 152 */ 153 t1 = tsk->sched_info.pcount; 154 t2 = tsk->sched_info.run_delay; 155 t3 = tsk->se.sum_exec_runtime; 156 157 d->cpu_count += t1; 158 159 d->cpu_delay_max = tsk->sched_info.max_run_delay; 160 tmp = (s64)d->cpu_delay_total + t2; 161 d->cpu_delay_total = (tmp < (s64)d->cpu_delay_total) ? 0 : tmp; 162 tmp = (s64)d->cpu_run_virtual_total + t3; 163 164 d->cpu_run_virtual_total = 165 (tmp < (s64)d->cpu_run_virtual_total) ? 0 : tmp; 166 167 if (!tsk->delays) 168 return 0; 169 170 /* zero XXX_total, non-zero XXX_count implies XXX stat overflowed */ 171 raw_spin_lock_irqsave(&tsk->delays->lock, flags); 172 d->blkio_delay_max = tsk->delays->blkio_delay_max; 173 tmp = d->blkio_delay_total + tsk->delays->blkio_delay; 174 d->blkio_delay_total = (tmp < d->blkio_delay_total) ? 0 : tmp; 175 d->swapin_delay_max = tsk->delays->swapin_delay_max; 176 tmp = d->swapin_delay_total + tsk->delays->swapin_delay; 177 d->swapin_delay_total = (tmp < d->swapin_delay_total) ? 0 : tmp; 178 d->freepages_delay_max = tsk->delays->freepages_delay_max; 179 tmp = d->freepages_delay_total + tsk->delays->freepages_delay; 180 d->freepages_delay_total = (tmp < d->freepages_delay_total) ? 0 : tmp; 181 d->thrashing_delay_max = tsk->delays->thrashing_delay_max; 182 tmp = d->thrashing_delay_total + tsk->delays->thrashing_delay; 183 d->thrashing_delay_total = (tmp < d->thrashing_delay_total) ? 0 : tmp; 184 d->compact_delay_max = tsk->delays->compact_delay_max; 185 tmp = d->compact_delay_total + tsk->delays->compact_delay; 186 d->compact_delay_total = (tmp < d->compact_delay_total) ? 0 : tmp; 187 d->wpcopy_delay_max = tsk->delays->wpcopy_delay_max; 188 tmp = d->wpcopy_delay_total + tsk->delays->wpcopy_delay; 189 d->wpcopy_delay_total = (tmp < d->wpcopy_delay_total) ? 0 : tmp; 190 d->irq_delay_max = tsk->delays->irq_delay_max; 191 tmp = d->irq_delay_total + tsk->delays->irq_delay; 192 d->irq_delay_total = (tmp < d->irq_delay_total) ? 0 : tmp; 193 d->blkio_count += tsk->delays->blkio_count; 194 d->swapin_count += tsk->delays->swapin_count; 195 d->freepages_count += tsk->delays->freepages_count; 196 d->thrashing_count += tsk->delays->thrashing_count; 197 d->compact_count += tsk->delays->compact_count; 198 d->wpcopy_count += tsk->delays->wpcopy_count; 199 d->irq_count += tsk->delays->irq_count; 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 } 229 230 void __delayacct_thrashing_start(bool *in_thrashing) 231 { 232 *in_thrashing = !!current->in_thrashing; 233 if (*in_thrashing) 234 return; 235 236 current->in_thrashing = 1; 237 current->delays->thrashing_start = local_clock(); 238 } 239 240 void __delayacct_thrashing_end(bool *in_thrashing) 241 { 242 if (*in_thrashing) 243 return; 244 245 current->in_thrashing = 0; 246 delayacct_end(¤t->delays->lock, 247 ¤t->delays->thrashing_start, 248 ¤t->delays->thrashing_delay, 249 ¤t->delays->thrashing_count, 250 ¤t->delays->thrashing_delay_max); 251 } 252 253 void __delayacct_swapin_start(void) 254 { 255 current->delays->swapin_start = local_clock(); 256 } 257 258 void __delayacct_swapin_end(void) 259 { 260 delayacct_end(¤t->delays->lock, 261 ¤t->delays->swapin_start, 262 ¤t->delays->swapin_delay, 263 ¤t->delays->swapin_count, 264 ¤t->delays->swapin_delay_max); 265 } 266 267 void __delayacct_compact_start(void) 268 { 269 current->delays->compact_start = local_clock(); 270 } 271 272 void __delayacct_compact_end(void) 273 { 274 delayacct_end(¤t->delays->lock, 275 ¤t->delays->compact_start, 276 ¤t->delays->compact_delay, 277 ¤t->delays->compact_count, 278 ¤t->delays->compact_delay_max); 279 } 280 281 void __delayacct_wpcopy_start(void) 282 { 283 current->delays->wpcopy_start = local_clock(); 284 } 285 286 void __delayacct_wpcopy_end(void) 287 { 288 delayacct_end(¤t->delays->lock, 289 ¤t->delays->wpcopy_start, 290 ¤t->delays->wpcopy_delay, 291 ¤t->delays->wpcopy_count, 292 ¤t->delays->wpcopy_delay_max); 293 } 294 295 void __delayacct_irq(struct task_struct *task, u32 delta) 296 { 297 unsigned long flags; 298 299 raw_spin_lock_irqsave(&task->delays->lock, flags); 300 task->delays->irq_delay += delta; 301 task->delays->irq_count++; 302 if (delta > task->delays->irq_delay_max) 303 task->delays->irq_delay_max = delta; 304 raw_spin_unlock_irqrestore(&task->delays->lock, flags); 305 } 306 307