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/slab.h> 18 #include <linux/taskstats.h> 19 #include <linux/time.h> 20 #include <linux/sysctl.h> 21 #include <linux/delayacct.h> 22 #include <linux/module.h> 23 24 int delayacct_on __read_mostly = 1; /* Delay accounting turned on/off */ 25 EXPORT_SYMBOL_GPL(delayacct_on); 26 struct kmem_cache *delayacct_cache; 27 28 static int __init delayacct_setup_disable(char *str) 29 { 30 delayacct_on = 0; 31 return 1; 32 } 33 __setup("nodelayacct", delayacct_setup_disable); 34 35 void delayacct_init(void) 36 { 37 delayacct_cache = KMEM_CACHE(task_delay_info, SLAB_PANIC|SLAB_ACCOUNT); 38 delayacct_tsk_init(&init_task); 39 } 40 41 void __delayacct_tsk_init(struct task_struct *tsk) 42 { 43 tsk->delays = kmem_cache_zalloc(delayacct_cache, GFP_KERNEL); 44 if (tsk->delays) 45 spin_lock_init(&tsk->delays->lock); 46 } 47 48 /* 49 * Finish delay accounting for a statistic using its timestamps (@start), 50 * accumalator (@total) and @count 51 */ 52 static void delayacct_end(u64 *start, u64 *total, u32 *count) 53 { 54 s64 ns = ktime_get_ns() - *start; 55 unsigned long flags; 56 57 if (ns > 0) { 58 spin_lock_irqsave(¤t->delays->lock, flags); 59 *total += ns; 60 (*count)++; 61 spin_unlock_irqrestore(¤t->delays->lock, flags); 62 } 63 } 64 65 void __delayacct_blkio_start(void) 66 { 67 current->delays->blkio_start = ktime_get_ns(); 68 } 69 70 void __delayacct_blkio_end(void) 71 { 72 if (current->delays->flags & DELAYACCT_PF_SWAPIN) 73 /* Swapin block I/O */ 74 delayacct_end(¤t->delays->blkio_start, 75 ¤t->delays->swapin_delay, 76 ¤t->delays->swapin_count); 77 else /* Other block I/O */ 78 delayacct_end(¤t->delays->blkio_start, 79 ¤t->delays->blkio_delay, 80 ¤t->delays->blkio_count); 81 } 82 83 int __delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk) 84 { 85 cputime_t 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 += cputime_to_nsecs(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 += cputime_to_nsecs(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 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 d->blkio_count += tsk->delays->blkio_count; 128 d->swapin_count += tsk->delays->swapin_count; 129 d->freepages_count += tsk->delays->freepages_count; 130 spin_unlock_irqrestore(&tsk->delays->lock, flags); 131 132 return 0; 133 } 134 135 __u64 __delayacct_blkio_ticks(struct task_struct *tsk) 136 { 137 __u64 ret; 138 unsigned long flags; 139 140 spin_lock_irqsave(&tsk->delays->lock, flags); 141 ret = nsec_to_clock_t(tsk->delays->blkio_delay + 142 tsk->delays->swapin_delay); 143 spin_unlock_irqrestore(&tsk->delays->lock, flags); 144 return ret; 145 } 146 147 void __delayacct_freepages_start(void) 148 { 149 current->delays->freepages_start = ktime_get_ns(); 150 } 151 152 void __delayacct_freepages_end(void) 153 { 154 delayacct_end(¤t->delays->freepages_start, 155 ¤t->delays->freepages_delay, 156 ¤t->delays->freepages_count); 157 } 158 159