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); 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 50 * its timestamps (@start, @end), accumalator (@total) and @count 51 */ 52 53 static void delayacct_end(struct timespec *start, struct timespec *end, 54 u64 *total, u32 *count) 55 { 56 struct timespec ts; 57 s64 ns; 58 unsigned long flags; 59 60 ktime_get_ts(end); 61 ts = timespec_sub(*end, *start); 62 ns = timespec_to_ns(&ts); 63 if (ns < 0) 64 return; 65 66 spin_lock_irqsave(¤t->delays->lock, flags); 67 *total += ns; 68 (*count)++; 69 spin_unlock_irqrestore(¤t->delays->lock, flags); 70 } 71 72 void __delayacct_blkio_start(void) 73 { 74 ktime_get_ts(¤t->delays->blkio_start); 75 } 76 77 void __delayacct_blkio_end(void) 78 { 79 if (current->delays->flags & DELAYACCT_PF_SWAPIN) 80 /* Swapin block I/O */ 81 delayacct_end(¤t->delays->blkio_start, 82 ¤t->delays->blkio_end, 83 ¤t->delays->swapin_delay, 84 ¤t->delays->swapin_count); 85 else /* Other block I/O */ 86 delayacct_end(¤t->delays->blkio_start, 87 ¤t->delays->blkio_end, 88 ¤t->delays->blkio_delay, 89 ¤t->delays->blkio_count); 90 } 91 92 int __delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk) 93 { 94 s64 tmp; 95 unsigned long t1; 96 unsigned long long t2, t3; 97 unsigned long flags; 98 struct timespec ts; 99 cputime_t utime, stime, stimescaled, utimescaled; 100 101 tmp = (s64)d->cpu_run_real_total; 102 task_cputime(tsk, &utime, &stime); 103 cputime_to_timespec(utime + stime, &ts); 104 tmp += timespec_to_ns(&ts); 105 d->cpu_run_real_total = (tmp < (s64)d->cpu_run_real_total) ? 0 : tmp; 106 107 tmp = (s64)d->cpu_scaled_run_real_total; 108 task_cputime_scaled(tsk, &utimescaled, &stimescaled); 109 cputime_to_timespec(utimescaled + stimescaled, &ts); 110 tmp += timespec_to_ns(&ts); 111 d->cpu_scaled_run_real_total = 112 (tmp < (s64)d->cpu_scaled_run_real_total) ? 0 : tmp; 113 114 /* 115 * No locking available for sched_info (and too expensive to add one) 116 * Mitigate by taking snapshot of values 117 */ 118 t1 = tsk->sched_info.pcount; 119 t2 = tsk->sched_info.run_delay; 120 t3 = tsk->se.sum_exec_runtime; 121 122 d->cpu_count += t1; 123 124 tmp = (s64)d->cpu_delay_total + t2; 125 d->cpu_delay_total = (tmp < (s64)d->cpu_delay_total) ? 0 : tmp; 126 127 tmp = (s64)d->cpu_run_virtual_total + t3; 128 d->cpu_run_virtual_total = 129 (tmp < (s64)d->cpu_run_virtual_total) ? 0 : tmp; 130 131 /* zero XXX_total, non-zero XXX_count implies XXX stat overflowed */ 132 133 spin_lock_irqsave(&tsk->delays->lock, flags); 134 tmp = d->blkio_delay_total + tsk->delays->blkio_delay; 135 d->blkio_delay_total = (tmp < d->blkio_delay_total) ? 0 : tmp; 136 tmp = d->swapin_delay_total + tsk->delays->swapin_delay; 137 d->swapin_delay_total = (tmp < d->swapin_delay_total) ? 0 : tmp; 138 tmp = d->freepages_delay_total + tsk->delays->freepages_delay; 139 d->freepages_delay_total = (tmp < d->freepages_delay_total) ? 0 : tmp; 140 d->blkio_count += tsk->delays->blkio_count; 141 d->swapin_count += tsk->delays->swapin_count; 142 d->freepages_count += tsk->delays->freepages_count; 143 spin_unlock_irqrestore(&tsk->delays->lock, flags); 144 145 return 0; 146 } 147 148 __u64 __delayacct_blkio_ticks(struct task_struct *tsk) 149 { 150 __u64 ret; 151 unsigned long flags; 152 153 spin_lock_irqsave(&tsk->delays->lock, flags); 154 ret = nsec_to_clock_t(tsk->delays->blkio_delay + 155 tsk->delays->swapin_delay); 156 spin_unlock_irqrestore(&tsk->delays->lock, flags); 157 return ret; 158 } 159 160 void __delayacct_freepages_start(void) 161 { 162 ktime_get_ts(¤t->delays->freepages_start); 163 } 164 165 void __delayacct_freepages_end(void) 166 { 167 delayacct_end(¤t->delays->freepages_start, 168 ¤t->delays->freepages_end, 169 ¤t->delays->freepages_delay, 170 ¤t->delays->freepages_count); 171 } 172 173