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(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(¤t->delays->lock, flags); 61 *total += ns; 62 (*count)++; 63 spin_unlock_irqrestore(¤t->delays->lock, flags); 64 } 65 } 66 67 void __delayacct_blkio_start(void) 68 { 69 current->delays->blkio_start = ktime_get_ns(); 70 } 71 72 void __delayacct_blkio_end(void) 73 { 74 if (current->delays->flags & DELAYACCT_PF_SWAPIN) 75 /* Swapin block I/O */ 76 delayacct_end(¤t->delays->blkio_start, 77 ¤t->delays->swapin_delay, 78 ¤t->delays->swapin_count); 79 else /* Other block I/O */ 80 delayacct_end(¤t->delays->blkio_start, 81 ¤t->delays->blkio_delay, 82 ¤t->delays->blkio_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 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 d->blkio_count += tsk->delays->blkio_count; 130 d->swapin_count += tsk->delays->swapin_count; 131 d->freepages_count += tsk->delays->freepages_count; 132 spin_unlock_irqrestore(&tsk->delays->lock, flags); 133 134 return 0; 135 } 136 137 __u64 __delayacct_blkio_ticks(struct task_struct *tsk) 138 { 139 __u64 ret; 140 unsigned long flags; 141 142 spin_lock_irqsave(&tsk->delays->lock, flags); 143 ret = nsec_to_clock_t(tsk->delays->blkio_delay + 144 tsk->delays->swapin_delay); 145 spin_unlock_irqrestore(&tsk->delays->lock, flags); 146 return ret; 147 } 148 149 void __delayacct_freepages_start(void) 150 { 151 current->delays->freepages_start = ktime_get_ns(); 152 } 153 154 void __delayacct_freepages_end(void) 155 { 156 delayacct_end(¤t->delays->freepages_start, 157 ¤t->delays->freepages_delay, 158 ¤t->delays->freepages_count); 159 } 160 161