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/time.h> 19 #include <linux/sysctl.h> 20 #include <linux/delayacct.h> 21 22 int delayacct_on __read_mostly = 1; /* Delay accounting turned on/off */ 23 struct kmem_cache *delayacct_cache; 24 25 static int __init delayacct_setup_disable(char *str) 26 { 27 delayacct_on = 0; 28 return 1; 29 } 30 __setup("nodelayacct", delayacct_setup_disable); 31 32 void delayacct_init(void) 33 { 34 delayacct_cache = kmem_cache_create("delayacct_cache", 35 sizeof(struct task_delay_info), 36 0, 37 SLAB_PANIC, 38 NULL, NULL); 39 delayacct_tsk_init(&init_task); 40 } 41 42 void __delayacct_tsk_init(struct task_struct *tsk) 43 { 44 tsk->delays = kmem_cache_zalloc(delayacct_cache, GFP_KERNEL); 45 if (tsk->delays) 46 spin_lock_init(&tsk->delays->lock); 47 } 48 49 /* 50 * Start accounting for a delay statistic using 51 * its starting timestamp (@start) 52 */ 53 54 static inline void delayacct_start(struct timespec *start) 55 { 56 do_posix_clock_monotonic_gettime(start); 57 } 58 59 /* 60 * Finish delay accounting for a statistic using 61 * its timestamps (@start, @end), accumalator (@total) and @count 62 */ 63 64 static void delayacct_end(struct timespec *start, struct timespec *end, 65 u64 *total, u32 *count) 66 { 67 struct timespec ts; 68 s64 ns; 69 unsigned long flags; 70 71 do_posix_clock_monotonic_gettime(end); 72 ts = timespec_sub(*end, *start); 73 ns = timespec_to_ns(&ts); 74 if (ns < 0) 75 return; 76 77 spin_lock_irqsave(¤t->delays->lock, flags); 78 *total += ns; 79 (*count)++; 80 spin_unlock_irqrestore(¤t->delays->lock, flags); 81 } 82 83 void __delayacct_blkio_start(void) 84 { 85 delayacct_start(¤t->delays->blkio_start); 86 } 87 88 void __delayacct_blkio_end(void) 89 { 90 if (current->delays->flags & DELAYACCT_PF_SWAPIN) 91 /* Swapin block I/O */ 92 delayacct_end(¤t->delays->blkio_start, 93 ¤t->delays->blkio_end, 94 ¤t->delays->swapin_delay, 95 ¤t->delays->swapin_count); 96 else /* Other block I/O */ 97 delayacct_end(¤t->delays->blkio_start, 98 ¤t->delays->blkio_end, 99 ¤t->delays->blkio_delay, 100 ¤t->delays->blkio_count); 101 } 102 103 int __delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk) 104 { 105 s64 tmp; 106 struct timespec ts; 107 unsigned long t1,t2,t3; 108 unsigned long flags; 109 110 /* Though tsk->delays accessed later, early exit avoids 111 * unnecessary returning of other data 112 */ 113 if (!tsk->delays) 114 goto done; 115 116 tmp = (s64)d->cpu_run_real_total; 117 cputime_to_timespec(tsk->utime + tsk->stime, &ts); 118 tmp += timespec_to_ns(&ts); 119 d->cpu_run_real_total = (tmp < (s64)d->cpu_run_real_total) ? 0 : tmp; 120 121 /* 122 * No locking available for sched_info (and too expensive to add one) 123 * Mitigate by taking snapshot of values 124 */ 125 t1 = tsk->sched_info.pcnt; 126 t2 = tsk->sched_info.run_delay; 127 t3 = tsk->sched_info.cpu_time; 128 129 d->cpu_count += t1; 130 131 jiffies_to_timespec(t2, &ts); 132 tmp = (s64)d->cpu_delay_total + timespec_to_ns(&ts); 133 d->cpu_delay_total = (tmp < (s64)d->cpu_delay_total) ? 0 : tmp; 134 135 tmp = (s64)d->cpu_run_virtual_total + (s64)jiffies_to_usecs(t3) * 1000; 136 d->cpu_run_virtual_total = 137 (tmp < (s64)d->cpu_run_virtual_total) ? 0 : tmp; 138 139 /* zero XXX_total, non-zero XXX_count implies XXX stat overflowed */ 140 141 spin_lock_irqsave(&tsk->delays->lock, flags); 142 tmp = d->blkio_delay_total + tsk->delays->blkio_delay; 143 d->blkio_delay_total = (tmp < d->blkio_delay_total) ? 0 : tmp; 144 tmp = d->swapin_delay_total + tsk->delays->swapin_delay; 145 d->swapin_delay_total = (tmp < d->swapin_delay_total) ? 0 : tmp; 146 d->blkio_count += tsk->delays->blkio_count; 147 d->swapin_count += tsk->delays->swapin_count; 148 spin_unlock_irqrestore(&tsk->delays->lock, flags); 149 150 done: 151 return 0; 152 } 153 154 __u64 __delayacct_blkio_ticks(struct task_struct *tsk) 155 { 156 __u64 ret; 157 unsigned long flags; 158 159 spin_lock_irqsave(&tsk->delays->lock, flags); 160 ret = nsec_to_clock_t(tsk->delays->blkio_delay + 161 tsk->delays->swapin_delay); 162 spin_unlock_irqrestore(&tsk->delays->lock, flags); 163 return ret; 164 } 165 166