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 } 178