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 * 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(¤t->delays->lock, 214 ¤t->delays->freepages_start, 215 ¤t->delays->freepages_delay, 216 ¤t->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(¤t->delays->lock, 236 ¤t->delays->thrashing_start, 237 ¤t->delays->thrashing_delay, 238 ¤t->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(¤t->delays->lock, 249 ¤t->delays->swapin_start, 250 ¤t->delays->swapin_delay, 251 ¤t->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(¤t->delays->lock, 262 ¤t->delays->compact_start, 263 ¤t->delays->compact_delay, 264 ¤t->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(¤t->delays->lock, 275 ¤t->delays->wpcopy_start, 276 ¤t->delays->wpcopy_delay, 277 ¤t->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 } 289 290