| 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/slab.h> |
| 11 | #include <linux/taskstats.h> |
| 12 | #include <linux/time.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 | EXPORT_SYMBOL_GPL(delayacct_on); |
| 19 | struct kmem_cache *delayacct_cache; |
| 20 | |
| 21 | static int __init delayacct_setup_disable(char *str) |
| 22 | { |
| 23 | delayacct_on = 0; |
| 24 | return 1; |
| 25 | } |
| 26 | __setup("nodelayacct", delayacct_setup_disable); |
| 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 | } |
| 33 | |
| 34 | void __delayacct_tsk_init(struct task_struct *tsk) |
| 35 | { |
| 36 | tsk->delays = kmem_cache_zalloc(delayacct_cache, GFP_KERNEL); |
| 37 | if (tsk->delays) |
| 38 | raw_spin_lock_init(&tsk->delays->lock); |
| 39 | } |
| 40 | |
| 41 | /* |
| 42 | * Finish delay accounting for a statistic using its timestamps (@start), |
| 43 | * accumalator (@total) and @count |
| 44 | */ |
| 45 | static void delayacct_end(raw_spinlock_t *lock, u64 *start, u64 *total, |
| 46 | u32 *count) |
| 47 | { |
| 48 | s64 ns = ktime_get_ns() - *start; |
| 49 | unsigned long flags; |
| 50 | |
| 51 | if (ns > 0) { |
| 52 | raw_spin_lock_irqsave(lock, flags); |
| 53 | *total += ns; |
| 54 | (*count)++; |
| 55 | raw_spin_unlock_irqrestore(lock, flags); |
| 56 | } |
| 57 | } |
| 58 | |
| 59 | void __delayacct_blkio_start(void) |
| 60 | { |
| 61 | current->delays->blkio_start = ktime_get_ns(); |
| 62 | } |
| 63 | |
| 64 | /* |
| 65 | * We cannot rely on the `current` macro, as we haven't yet switched back to |
| 66 | * the process being woken. |
| 67 | */ |
| 68 | void __delayacct_blkio_end(struct task_struct *p) |
| 69 | { |
| 70 | struct task_delay_info *delays = p->delays; |
| 71 | u64 *total; |
| 72 | u32 *count; |
| 73 | |
| 74 | if (p->delays->flags & DELAYACCT_PF_SWAPIN) { |
| 75 | total = &delays->swapin_delay; |
| 76 | count = &delays->swapin_count; |
| 77 | } else { |
| 78 | total = &delays->blkio_delay; |
| 79 | count = &delays->blkio_count; |
| 80 | } |
| 81 | |
| 82 | delayacct_end(&delays->lock, &delays->blkio_start, total, count); |
| 83 | } |
| 84 | |
| 85 | int __delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk) |
| 86 | { |
| 87 | u64 utime, stime, stimescaled, utimescaled; |
| 88 | unsigned long long t2, t3; |
| 89 | unsigned long flags, t1; |
| 90 | s64 tmp; |
| 91 | |
| 92 | task_cputime(tsk, &utime, &stime); |
| 93 | tmp = (s64)d->cpu_run_real_total; |
| 94 | tmp += utime + stime; |
| 95 | d->cpu_run_real_total = (tmp < (s64)d->cpu_run_real_total) ? 0 : tmp; |
| 96 | |
| 97 | task_cputime_scaled(tsk, &utimescaled, &stimescaled); |
| 98 | tmp = (s64)d->cpu_scaled_run_real_total; |
| 99 | tmp += utimescaled + stimescaled; |
| 100 | d->cpu_scaled_run_real_total = |
| 101 | (tmp < (s64)d->cpu_scaled_run_real_total) ? 0 : tmp; |
| 102 | |
| 103 | /* |
| 104 | * No locking available for sched_info (and too expensive to add one) |
| 105 | * Mitigate by taking snapshot of values |
| 106 | */ |
| 107 | t1 = tsk->sched_info.pcount; |
| 108 | t2 = tsk->sched_info.run_delay; |
| 109 | t3 = tsk->se.sum_exec_runtime; |
| 110 | |
| 111 | d->cpu_count += t1; |
| 112 | |
| 113 | tmp = (s64)d->cpu_delay_total + t2; |
| 114 | d->cpu_delay_total = (tmp < (s64)d->cpu_delay_total) ? 0 : tmp; |
| 115 | |
| 116 | tmp = (s64)d->cpu_run_virtual_total + t3; |
| 117 | d->cpu_run_virtual_total = |
| 118 | (tmp < (s64)d->cpu_run_virtual_total) ? 0 : tmp; |
| 119 | |
| 120 | /* zero XXX_total, non-zero XXX_count implies XXX stat overflowed */ |
| 121 | |
| 122 | raw_spin_lock_irqsave(&tsk->delays->lock, flags); |
| 123 | tmp = d->blkio_delay_total + tsk->delays->blkio_delay; |
| 124 | d->blkio_delay_total = (tmp < d->blkio_delay_total) ? 0 : tmp; |
| 125 | tmp = d->swapin_delay_total + tsk->delays->swapin_delay; |
| 126 | d->swapin_delay_total = (tmp < d->swapin_delay_total) ? 0 : tmp; |
| 127 | tmp = d->freepages_delay_total + tsk->delays->freepages_delay; |
| 128 | d->freepages_delay_total = (tmp < d->freepages_delay_total) ? 0 : tmp; |
| 129 | tmp = d->thrashing_delay_total + tsk->delays->thrashing_delay; |
| 130 | d->thrashing_delay_total = (tmp < d->thrashing_delay_total) ? 0 : tmp; |
| 131 | d->blkio_count += tsk->delays->blkio_count; |
| 132 | d->swapin_count += tsk->delays->swapin_count; |
| 133 | d->freepages_count += tsk->delays->freepages_count; |
| 134 | d->thrashing_count += tsk->delays->thrashing_count; |
| 135 | raw_spin_unlock_irqrestore(&tsk->delays->lock, flags); |
| 136 | |
| 137 | return 0; |
| 138 | } |
| 139 | |
| 140 | __u64 __delayacct_blkio_ticks(struct task_struct *tsk) |
| 141 | { |
| 142 | __u64 ret; |
| 143 | unsigned long flags; |
| 144 | |
| 145 | raw_spin_lock_irqsave(&tsk->delays->lock, flags); |
| 146 | ret = nsec_to_clock_t(tsk->delays->blkio_delay + |
| 147 | tsk->delays->swapin_delay); |
| 148 | raw_spin_unlock_irqrestore(&tsk->delays->lock, flags); |
| 149 | return ret; |
| 150 | } |
| 151 | |
| 152 | void __delayacct_freepages_start(void) |
| 153 | { |
| 154 | current->delays->freepages_start = ktime_get_ns(); |
| 155 | } |
| 156 | |
| 157 | void __delayacct_freepages_end(void) |
| 158 | { |
| 159 | delayacct_end( |
| 160 | ¤t->delays->lock, |
| 161 | ¤t->delays->freepages_start, |
| 162 | ¤t->delays->freepages_delay, |
| 163 | ¤t->delays->freepages_count); |
| 164 | } |
| 165 | |
| 166 | void __delayacct_thrashing_start(void) |
| 167 | { |
| 168 | current->delays->thrashing_start = ktime_get_ns(); |
| 169 | } |
| 170 | |
| 171 | void __delayacct_thrashing_end(void) |
| 172 | { |
| 173 | delayacct_end(¤t->delays->lock, |
| 174 | ¤t->delays->thrashing_start, |
| 175 | ¤t->delays->thrashing_delay, |
| 176 | ¤t->delays->thrashing_count); |
| 177 | } |