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 int __init delayacct_setup_enable(char *str) 22 { 23 delayacct_on = 1; 24 return 1; 25 } 26 __setup("delayacct", delayacct_setup_enable); 27 28 void delayacct_init(void) 29 { 30 delayacct_cache = KMEM_CACHE(task_delay_info, SLAB_PANIC|SLAB_ACCOUNT); 31 delayacct_tsk_init(&init_task); 32 if (delayacct_on) 33 static_branch_enable(&delayacct_key); 34 } 35 36 void __delayacct_tsk_init(struct task_struct *tsk) 37 { 38 tsk->delays = kmem_cache_zalloc(delayacct_cache, GFP_KERNEL); 39 if (tsk->delays) 40 raw_spin_lock_init(&tsk->delays->lock); 41 } 42 43 /* 44 * Finish delay accounting for a statistic using its timestamps (@start), 45 * accumalator (@total) and @count 46 */ 47 static void delayacct_end(raw_spinlock_t *lock, u64 *start, u64 *total, u32 *count) 48 { 49 s64 ns = local_clock() - *start; 50 unsigned long flags; 51 52 if (ns > 0) { 53 raw_spin_lock_irqsave(lock, flags); 54 *total += ns; 55 (*count)++; 56 raw_spin_unlock_irqrestore(lock, flags); 57 } 58 } 59 60 void __delayacct_blkio_start(void) 61 { 62 current->delays->blkio_start = local_clock(); 63 } 64 65 /* 66 * We cannot rely on the `current` macro, as we haven't yet switched back to 67 * the process being woken. 68 */ 69 void __delayacct_blkio_end(struct task_struct *p) 70 { 71 struct task_delay_info *delays = p->delays; 72 u64 *total; 73 u32 *count; 74 75 if (p->delays->flags & DELAYACCT_PF_SWAPIN) { 76 total = &delays->swapin_delay; 77 count = &delays->swapin_count; 78 } else { 79 total = &delays->blkio_delay; 80 count = &delays->blkio_count; 81 } 82 83 delayacct_end(&delays->lock, &delays->blkio_start, total, count); 84 } 85 86 int delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk) 87 { 88 u64 utime, stime, stimescaled, utimescaled; 89 unsigned long long t2, t3; 90 unsigned long flags, t1; 91 s64 tmp; 92 93 task_cputime(tsk, &utime, &stime); 94 tmp = (s64)d->cpu_run_real_total; 95 tmp += utime + stime; 96 d->cpu_run_real_total = (tmp < (s64)d->cpu_run_real_total) ? 0 : tmp; 97 98 task_cputime_scaled(tsk, &utimescaled, &stimescaled); 99 tmp = (s64)d->cpu_scaled_run_real_total; 100 tmp += utimescaled + stimescaled; 101 d->cpu_scaled_run_real_total = 102 (tmp < (s64)d->cpu_scaled_run_real_total) ? 0 : tmp; 103 104 /* 105 * No locking available for sched_info (and too expensive to add one) 106 * Mitigate by taking snapshot of values 107 */ 108 t1 = tsk->sched_info.pcount; 109 t2 = tsk->sched_info.run_delay; 110 t3 = tsk->se.sum_exec_runtime; 111 112 d->cpu_count += t1; 113 114 tmp = (s64)d->cpu_delay_total + t2; 115 d->cpu_delay_total = (tmp < (s64)d->cpu_delay_total) ? 0 : tmp; 116 117 tmp = (s64)d->cpu_run_virtual_total + t3; 118 d->cpu_run_virtual_total = 119 (tmp < (s64)d->cpu_run_virtual_total) ? 0 : tmp; 120 121 if (!tsk->delays) 122 return 0; 123 124 /* zero XXX_total, non-zero XXX_count implies XXX stat overflowed */ 125 126 raw_spin_lock_irqsave(&tsk->delays->lock, flags); 127 tmp = d->blkio_delay_total + tsk->delays->blkio_delay; 128 d->blkio_delay_total = (tmp < d->blkio_delay_total) ? 0 : tmp; 129 tmp = d->swapin_delay_total + tsk->delays->swapin_delay; 130 d->swapin_delay_total = (tmp < d->swapin_delay_total) ? 0 : tmp; 131 tmp = d->freepages_delay_total + tsk->delays->freepages_delay; 132 d->freepages_delay_total = (tmp < d->freepages_delay_total) ? 0 : tmp; 133 tmp = d->thrashing_delay_total + tsk->delays->thrashing_delay; 134 d->thrashing_delay_total = (tmp < d->thrashing_delay_total) ? 0 : tmp; 135 d->blkio_count += tsk->delays->blkio_count; 136 d->swapin_count += tsk->delays->swapin_count; 137 d->freepages_count += tsk->delays->freepages_count; 138 d->thrashing_count += tsk->delays->thrashing_count; 139 raw_spin_unlock_irqrestore(&tsk->delays->lock, flags); 140 141 return 0; 142 } 143 144 __u64 __delayacct_blkio_ticks(struct task_struct *tsk) 145 { 146 __u64 ret; 147 unsigned long flags; 148 149 raw_spin_lock_irqsave(&tsk->delays->lock, flags); 150 ret = nsec_to_clock_t(tsk->delays->blkio_delay + 151 tsk->delays->swapin_delay); 152 raw_spin_unlock_irqrestore(&tsk->delays->lock, flags); 153 return ret; 154 } 155 156 void __delayacct_freepages_start(void) 157 { 158 current->delays->freepages_start = local_clock(); 159 } 160 161 void __delayacct_freepages_end(void) 162 { 163 delayacct_end(¤t->delays->lock, 164 ¤t->delays->freepages_start, 165 ¤t->delays->freepages_delay, 166 ¤t->delays->freepages_count); 167 } 168 169 void __delayacct_thrashing_start(void) 170 { 171 current->delays->thrashing_start = local_clock(); 172 } 173 174 void __delayacct_thrashing_end(void) 175 { 176 delayacct_end(¤t->delays->lock, 177 ¤t->delays->thrashing_start, 178 ¤t->delays->thrashing_delay, 179 ¤t->delays->thrashing_count); 180 } 181