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 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 #endif 67 68 void __delayacct_tsk_init(struct task_struct *tsk) 69 { 70 tsk->delays = kmem_cache_zalloc(delayacct_cache, GFP_KERNEL); 71 if (tsk->delays) 72 raw_spin_lock_init(&tsk->delays->lock); 73 } 74 75 /* 76 * Finish delay accounting for a statistic using its timestamps (@start), 77 * accumalator (@total) and @count 78 */ 79 static void delayacct_end(raw_spinlock_t *lock, u64 *start, u64 *total, u32 *count) 80 { 81 s64 ns = local_clock() - *start; 82 unsigned long flags; 83 84 if (ns > 0) { 85 raw_spin_lock_irqsave(lock, flags); 86 *total += ns; 87 (*count)++; 88 raw_spin_unlock_irqrestore(lock, flags); 89 } 90 } 91 92 void __delayacct_blkio_start(void) 93 { 94 current->delays->blkio_start = local_clock(); 95 } 96 97 /* 98 * We cannot rely on the `current` macro, as we haven't yet switched back to 99 * the process being woken. 100 */ 101 void __delayacct_blkio_end(struct task_struct *p) 102 { 103 delayacct_end(&p->delays->lock, 104 &p->delays->blkio_start, 105 &p->delays->blkio_delay, 106 &p->delays->blkio_count); 107 } 108 109 int delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk) 110 { 111 u64 utime, stime, stimescaled, utimescaled; 112 unsigned long long t2, t3; 113 unsigned long flags, t1; 114 s64 tmp; 115 116 task_cputime(tsk, &utime, &stime); 117 tmp = (s64)d->cpu_run_real_total; 118 tmp += utime + stime; 119 d->cpu_run_real_total = (tmp < (s64)d->cpu_run_real_total) ? 0 : tmp; 120 121 task_cputime_scaled(tsk, &utimescaled, &stimescaled); 122 tmp = (s64)d->cpu_scaled_run_real_total; 123 tmp += utimescaled + stimescaled; 124 d->cpu_scaled_run_real_total = 125 (tmp < (s64)d->cpu_scaled_run_real_total) ? 0 : tmp; 126 127 /* 128 * No locking available for sched_info (and too expensive to add one) 129 * Mitigate by taking snapshot of values 130 */ 131 t1 = tsk->sched_info.pcount; 132 t2 = tsk->sched_info.run_delay; 133 t3 = tsk->se.sum_exec_runtime; 134 135 d->cpu_count += t1; 136 137 tmp = (s64)d->cpu_delay_total + t2; 138 d->cpu_delay_total = (tmp < (s64)d->cpu_delay_total) ? 0 : tmp; 139 140 tmp = (s64)d->cpu_run_virtual_total + t3; 141 d->cpu_run_virtual_total = 142 (tmp < (s64)d->cpu_run_virtual_total) ? 0 : tmp; 143 144 if (!tsk->delays) 145 return 0; 146 147 /* zero XXX_total, non-zero XXX_count implies XXX stat overflowed */ 148 149 raw_spin_lock_irqsave(&tsk->delays->lock, flags); 150 tmp = d->blkio_delay_total + tsk->delays->blkio_delay; 151 d->blkio_delay_total = (tmp < d->blkio_delay_total) ? 0 : tmp; 152 tmp = d->swapin_delay_total + tsk->delays->swapin_delay; 153 d->swapin_delay_total = (tmp < d->swapin_delay_total) ? 0 : tmp; 154 tmp = d->freepages_delay_total + tsk->delays->freepages_delay; 155 d->freepages_delay_total = (tmp < d->freepages_delay_total) ? 0 : tmp; 156 tmp = d->thrashing_delay_total + tsk->delays->thrashing_delay; 157 d->thrashing_delay_total = (tmp < d->thrashing_delay_total) ? 0 : tmp; 158 tmp = d->compact_delay_total + tsk->delays->compact_delay; 159 d->compact_delay_total = (tmp < d->compact_delay_total) ? 0 : tmp; 160 d->blkio_count += tsk->delays->blkio_count; 161 d->swapin_count += tsk->delays->swapin_count; 162 d->freepages_count += tsk->delays->freepages_count; 163 d->thrashing_count += tsk->delays->thrashing_count; 164 d->compact_count += tsk->delays->compact_count; 165 raw_spin_unlock_irqrestore(&tsk->delays->lock, flags); 166 167 return 0; 168 } 169 170 __u64 __delayacct_blkio_ticks(struct task_struct *tsk) 171 { 172 __u64 ret; 173 unsigned long flags; 174 175 raw_spin_lock_irqsave(&tsk->delays->lock, flags); 176 ret = nsec_to_clock_t(tsk->delays->blkio_delay); 177 raw_spin_unlock_irqrestore(&tsk->delays->lock, flags); 178 return ret; 179 } 180 181 void __delayacct_freepages_start(void) 182 { 183 current->delays->freepages_start = local_clock(); 184 } 185 186 void __delayacct_freepages_end(void) 187 { 188 delayacct_end(¤t->delays->lock, 189 ¤t->delays->freepages_start, 190 ¤t->delays->freepages_delay, 191 ¤t->delays->freepages_count); 192 } 193 194 void __delayacct_thrashing_start(void) 195 { 196 current->delays->thrashing_start = local_clock(); 197 } 198 199 void __delayacct_thrashing_end(void) 200 { 201 delayacct_end(¤t->delays->lock, 202 ¤t->delays->thrashing_start, 203 ¤t->delays->thrashing_delay, 204 ¤t->delays->thrashing_count); 205 } 206 207 void __delayacct_swapin_start(void) 208 { 209 current->delays->swapin_start = local_clock(); 210 } 211 212 void __delayacct_swapin_end(void) 213 { 214 delayacct_end(¤t->delays->lock, 215 ¤t->delays->swapin_start, 216 ¤t->delays->swapin_delay, 217 ¤t->delays->swapin_count); 218 } 219 220 void __delayacct_compact_start(void) 221 { 222 current->delays->compact_start = local_clock(); 223 } 224 225 void __delayacct_compact_end(void) 226 { 227 delayacct_end(¤t->delays->lock, 228 ¤t->delays->compact_start, 229 ¤t->delays->compact_delay, 230 ¤t->delays->compact_count); 231 } 232