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 int delayacct_on __read_mostly = 1; /* Delay accounting turned on/off */ 18 struct kmem_cache *delayacct_cache; 19 20 static int __init delayacct_setup_disable(char *str) 21 { 22 delayacct_on = 0; 23 return 1; 24 } 25 __setup("nodelayacct", delayacct_setup_disable); 26 27 void delayacct_init(void) 28 { 29 delayacct_cache = KMEM_CACHE(task_delay_info, SLAB_PANIC|SLAB_ACCOUNT); 30 delayacct_tsk_init(&init_task); 31 } 32 33 void __delayacct_tsk_init(struct task_struct *tsk) 34 { 35 tsk->delays = kmem_cache_zalloc(delayacct_cache, GFP_KERNEL); 36 if (tsk->delays) 37 raw_spin_lock_init(&tsk->delays->lock); 38 } 39 40 /* 41 * Finish delay accounting for a statistic using its timestamps (@start), 42 * accumalator (@total) and @count 43 */ 44 static void delayacct_end(raw_spinlock_t *lock, u64 *start, u64 *total, u32 *count) 45 { 46 s64 ns = local_clock() - *start; 47 unsigned long flags; 48 49 if (ns > 0) { 50 raw_spin_lock_irqsave(lock, flags); 51 *total += ns; 52 (*count)++; 53 raw_spin_unlock_irqrestore(lock, flags); 54 } 55 } 56 57 void __delayacct_blkio_start(void) 58 { 59 current->delays->blkio_start = local_clock(); 60 } 61 62 /* 63 * We cannot rely on the `current` macro, as we haven't yet switched back to 64 * the process being woken. 65 */ 66 void __delayacct_blkio_end(struct task_struct *p) 67 { 68 struct task_delay_info *delays = p->delays; 69 u64 *total; 70 u32 *count; 71 72 if (p->delays->flags & DELAYACCT_PF_SWAPIN) { 73 total = &delays->swapin_delay; 74 count = &delays->swapin_count; 75 } else { 76 total = &delays->blkio_delay; 77 count = &delays->blkio_count; 78 } 79 80 delayacct_end(&delays->lock, &delays->blkio_start, total, count); 81 } 82 83 int __delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk) 84 { 85 u64 utime, stime, stimescaled, utimescaled; 86 unsigned long long t2, t3; 87 unsigned long flags, t1; 88 s64 tmp; 89 90 task_cputime(tsk, &utime, &stime); 91 tmp = (s64)d->cpu_run_real_total; 92 tmp += utime + stime; 93 d->cpu_run_real_total = (tmp < (s64)d->cpu_run_real_total) ? 0 : tmp; 94 95 task_cputime_scaled(tsk, &utimescaled, &stimescaled); 96 tmp = (s64)d->cpu_scaled_run_real_total; 97 tmp += utimescaled + stimescaled; 98 d->cpu_scaled_run_real_total = 99 (tmp < (s64)d->cpu_scaled_run_real_total) ? 0 : tmp; 100 101 /* 102 * No locking available for sched_info (and too expensive to add one) 103 * Mitigate by taking snapshot of values 104 */ 105 t1 = tsk->sched_info.pcount; 106 t2 = tsk->sched_info.run_delay; 107 t3 = tsk->se.sum_exec_runtime; 108 109 d->cpu_count += t1; 110 111 tmp = (s64)d->cpu_delay_total + t2; 112 d->cpu_delay_total = (tmp < (s64)d->cpu_delay_total) ? 0 : tmp; 113 114 tmp = (s64)d->cpu_run_virtual_total + t3; 115 d->cpu_run_virtual_total = 116 (tmp < (s64)d->cpu_run_virtual_total) ? 0 : tmp; 117 118 /* zero XXX_total, non-zero XXX_count implies XXX stat overflowed */ 119 120 raw_spin_lock_irqsave(&tsk->delays->lock, flags); 121 tmp = d->blkio_delay_total + tsk->delays->blkio_delay; 122 d->blkio_delay_total = (tmp < d->blkio_delay_total) ? 0 : tmp; 123 tmp = d->swapin_delay_total + tsk->delays->swapin_delay; 124 d->swapin_delay_total = (tmp < d->swapin_delay_total) ? 0 : tmp; 125 tmp = d->freepages_delay_total + tsk->delays->freepages_delay; 126 d->freepages_delay_total = (tmp < d->freepages_delay_total) ? 0 : tmp; 127 tmp = d->thrashing_delay_total + tsk->delays->thrashing_delay; 128 d->thrashing_delay_total = (tmp < d->thrashing_delay_total) ? 0 : tmp; 129 d->blkio_count += tsk->delays->blkio_count; 130 d->swapin_count += tsk->delays->swapin_count; 131 d->freepages_count += tsk->delays->freepages_count; 132 d->thrashing_count += tsk->delays->thrashing_count; 133 raw_spin_unlock_irqrestore(&tsk->delays->lock, flags); 134 135 return 0; 136 } 137 138 __u64 __delayacct_blkio_ticks(struct task_struct *tsk) 139 { 140 __u64 ret; 141 unsigned long flags; 142 143 raw_spin_lock_irqsave(&tsk->delays->lock, flags); 144 ret = nsec_to_clock_t(tsk->delays->blkio_delay + 145 tsk->delays->swapin_delay); 146 raw_spin_unlock_irqrestore(&tsk->delays->lock, flags); 147 return ret; 148 } 149 150 void __delayacct_freepages_start(void) 151 { 152 current->delays->freepages_start = local_clock(); 153 } 154 155 void __delayacct_freepages_end(void) 156 { 157 delayacct_end(¤t->delays->lock, 158 ¤t->delays->freepages_start, 159 ¤t->delays->freepages_delay, 160 ¤t->delays->freepages_count); 161 } 162 163 void __delayacct_thrashing_start(void) 164 { 165 current->delays->thrashing_start = local_clock(); 166 } 167 168 void __delayacct_thrashing_end(void) 169 { 170 delayacct_end(¤t->delays->lock, 171 ¤t->delays->thrashing_start, 172 ¤t->delays->thrashing_delay, 173 ¤t->delays->thrashing_count); 174 } 175