1 /* delayacct.c - per-task delay accounting 2 * 3 * Copyright (C) Shailabh Nagar, IBM Corp. 2006 4 * 5 * This program is free software; you can redistribute it and/or modify 6 * it under the terms of the GNU General Public License as published by 7 * the Free Software Foundation; either version 2 of the License, or 8 * (at your option) any later version. 9 * 10 * This program is distributed in the hope that it would be useful, but 11 * WITHOUT ANY WARRANTY; without even the implied warranty of 12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See 13 * the GNU General Public License for more details. 14 */ 15 16 #include <linux/sched.h> 17 #include <linux/sched/task.h> 18 #include <linux/sched/cputime.h> 19 #include <linux/slab.h> 20 #include <linux/taskstats.h> 21 #include <linux/time.h> 22 #include <linux/sysctl.h> 23 #include <linux/delayacct.h> 24 #include <linux/module.h> 25 26 int delayacct_on __read_mostly = 1; /* Delay accounting turned on/off */ 27 EXPORT_SYMBOL_GPL(delayacct_on); 28 struct kmem_cache *delayacct_cache; 29 30 static int __init delayacct_setup_disable(char *str) 31 { 32 delayacct_on = 0; 33 return 1; 34 } 35 __setup("nodelayacct", delayacct_setup_disable); 36 37 void delayacct_init(void) 38 { 39 delayacct_cache = KMEM_CACHE(task_delay_info, SLAB_PANIC|SLAB_ACCOUNT); 40 delayacct_tsk_init(&init_task); 41 } 42 43 void __delayacct_tsk_init(struct task_struct *tsk) 44 { 45 tsk->delays = kmem_cache_zalloc(delayacct_cache, GFP_KERNEL); 46 if (tsk->delays) 47 spin_lock_init(&tsk->delays->lock); 48 } 49 50 /* 51 * Finish delay accounting for a statistic using its timestamps (@start), 52 * accumalator (@total) and @count 53 */ 54 static void delayacct_end(spinlock_t *lock, u64 *start, u64 *total, u32 *count) 55 { 56 s64 ns = ktime_get_ns() - *start; 57 unsigned long flags; 58 59 if (ns > 0) { 60 spin_lock_irqsave(lock, flags); 61 *total += ns; 62 (*count)++; 63 spin_unlock_irqrestore(lock, flags); 64 } 65 } 66 67 void __delayacct_blkio_start(void) 68 { 69 current->delays->blkio_start = ktime_get_ns(); 70 } 71 72 /* 73 * We cannot rely on the `current` macro, as we haven't yet switched back to 74 * the process being woken. 75 */ 76 void __delayacct_blkio_end(struct task_struct *p) 77 { 78 struct task_delay_info *delays = p->delays; 79 u64 *total; 80 u32 *count; 81 82 if (p->delays->flags & DELAYACCT_PF_SWAPIN) { 83 total = &delays->swapin_delay; 84 count = &delays->swapin_count; 85 } else { 86 total = &delays->blkio_delay; 87 count = &delays->blkio_count; 88 } 89 90 delayacct_end(&delays->lock, &delays->blkio_start, total, count); 91 } 92 93 int __delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk) 94 { 95 u64 utime, stime, stimescaled, utimescaled; 96 unsigned long long t2, t3; 97 unsigned long flags, t1; 98 s64 tmp; 99 100 task_cputime(tsk, &utime, &stime); 101 tmp = (s64)d->cpu_run_real_total; 102 tmp += utime + stime; 103 d->cpu_run_real_total = (tmp < (s64)d->cpu_run_real_total) ? 0 : tmp; 104 105 task_cputime_scaled(tsk, &utimescaled, &stimescaled); 106 tmp = (s64)d->cpu_scaled_run_real_total; 107 tmp += utimescaled + stimescaled; 108 d->cpu_scaled_run_real_total = 109 (tmp < (s64)d->cpu_scaled_run_real_total) ? 0 : tmp; 110 111 /* 112 * No locking available for sched_info (and too expensive to add one) 113 * Mitigate by taking snapshot of values 114 */ 115 t1 = tsk->sched_info.pcount; 116 t2 = tsk->sched_info.run_delay; 117 t3 = tsk->se.sum_exec_runtime; 118 119 d->cpu_count += t1; 120 121 tmp = (s64)d->cpu_delay_total + t2; 122 d->cpu_delay_total = (tmp < (s64)d->cpu_delay_total) ? 0 : tmp; 123 124 tmp = (s64)d->cpu_run_virtual_total + t3; 125 d->cpu_run_virtual_total = 126 (tmp < (s64)d->cpu_run_virtual_total) ? 0 : tmp; 127 128 /* zero XXX_total, non-zero XXX_count implies XXX stat overflowed */ 129 130 spin_lock_irqsave(&tsk->delays->lock, flags); 131 tmp = d->blkio_delay_total + tsk->delays->blkio_delay; 132 d->blkio_delay_total = (tmp < d->blkio_delay_total) ? 0 : tmp; 133 tmp = d->swapin_delay_total + tsk->delays->swapin_delay; 134 d->swapin_delay_total = (tmp < d->swapin_delay_total) ? 0 : tmp; 135 tmp = d->freepages_delay_total + tsk->delays->freepages_delay; 136 d->freepages_delay_total = (tmp < d->freepages_delay_total) ? 0 : tmp; 137 d->blkio_count += tsk->delays->blkio_count; 138 d->swapin_count += tsk->delays->swapin_count; 139 d->freepages_count += tsk->delays->freepages_count; 140 spin_unlock_irqrestore(&tsk->delays->lock, flags); 141 142 return 0; 143 } 144 145 __u64 __delayacct_blkio_ticks(struct task_struct *tsk) 146 { 147 __u64 ret; 148 unsigned long flags; 149 150 spin_lock_irqsave(&tsk->delays->lock, flags); 151 ret = nsec_to_clock_t(tsk->delays->blkio_delay + 152 tsk->delays->swapin_delay); 153 spin_unlock_irqrestore(&tsk->delays->lock, flags); 154 return ret; 155 } 156 157 void __delayacct_freepages_start(void) 158 { 159 current->delays->freepages_start = ktime_get_ns(); 160 } 161 162 void __delayacct_freepages_end(void) 163 { 164 delayacct_end( 165 ¤t->delays->lock, 166 ¤t->delays->freepages_start, 167 ¤t->delays->freepages_delay, 168 ¤t->delays->freepages_count); 169 } 170 171