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 kmem_cache_t *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 spin_lock_init(&tsk->delays_lock); 45 /* No need to acquire tsk->delays_lock for allocation here unless 46 __delayacct_tsk_init called after tsk is attached to tasklist 47 */ 48 tsk->delays = kmem_cache_zalloc(delayacct_cache, SLAB_KERNEL); 49 if (tsk->delays) 50 spin_lock_init(&tsk->delays->lock); 51 } 52 53 void __delayacct_tsk_exit(struct task_struct *tsk) 54 { 55 struct task_delay_info *delays = tsk->delays; 56 spin_lock(&tsk->delays_lock); 57 tsk->delays = NULL; 58 spin_unlock(&tsk->delays_lock); 59 kmem_cache_free(delayacct_cache, delays); 60 } 61 62 /* 63 * Start accounting for a delay statistic using 64 * its starting timestamp (@start) 65 */ 66 67 static inline void delayacct_start(struct timespec *start) 68 { 69 do_posix_clock_monotonic_gettime(start); 70 } 71 72 /* 73 * Finish delay accounting for a statistic using 74 * its timestamps (@start, @end), accumalator (@total) and @count 75 */ 76 77 static void delayacct_end(struct timespec *start, struct timespec *end, 78 u64 *total, u32 *count) 79 { 80 struct timespec ts; 81 s64 ns; 82 83 do_posix_clock_monotonic_gettime(end); 84 ts = timespec_sub(*end, *start); 85 ns = timespec_to_ns(&ts); 86 if (ns < 0) 87 return; 88 89 spin_lock(¤t->delays->lock); 90 *total += ns; 91 (*count)++; 92 spin_unlock(¤t->delays->lock); 93 } 94 95 void __delayacct_blkio_start(void) 96 { 97 delayacct_start(¤t->delays->blkio_start); 98 } 99 100 void __delayacct_blkio_end(void) 101 { 102 if (current->delays->flags & DELAYACCT_PF_SWAPIN) 103 /* Swapin block I/O */ 104 delayacct_end(¤t->delays->blkio_start, 105 ¤t->delays->blkio_end, 106 ¤t->delays->swapin_delay, 107 ¤t->delays->swapin_count); 108 else /* Other block I/O */ 109 delayacct_end(¤t->delays->blkio_start, 110 ¤t->delays->blkio_end, 111 ¤t->delays->blkio_delay, 112 ¤t->delays->blkio_count); 113 } 114 115 int __delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk) 116 { 117 s64 tmp; 118 struct timespec ts; 119 unsigned long t1,t2,t3; 120 121 spin_lock(&tsk->delays_lock); 122 123 /* Though tsk->delays accessed later, early exit avoids 124 * unnecessary returning of other data 125 */ 126 if (!tsk->delays) 127 goto done; 128 129 tmp = (s64)d->cpu_run_real_total; 130 cputime_to_timespec(tsk->utime + tsk->stime, &ts); 131 tmp += timespec_to_ns(&ts); 132 d->cpu_run_real_total = (tmp < (s64)d->cpu_run_real_total) ? 0 : tmp; 133 134 /* 135 * No locking available for sched_info (and too expensive to add one) 136 * Mitigate by taking snapshot of values 137 */ 138 t1 = tsk->sched_info.pcnt; 139 t2 = tsk->sched_info.run_delay; 140 t3 = tsk->sched_info.cpu_time; 141 142 d->cpu_count += t1; 143 144 jiffies_to_timespec(t2, &ts); 145 tmp = (s64)d->cpu_delay_total + timespec_to_ns(&ts); 146 d->cpu_delay_total = (tmp < (s64)d->cpu_delay_total) ? 0 : tmp; 147 148 tmp = (s64)d->cpu_run_virtual_total + (s64)jiffies_to_usecs(t3) * 1000; 149 d->cpu_run_virtual_total = 150 (tmp < (s64)d->cpu_run_virtual_total) ? 0 : tmp; 151 152 /* zero XXX_total, non-zero XXX_count implies XXX stat overflowed */ 153 154 spin_lock(&tsk->delays->lock); 155 tmp = d->blkio_delay_total + tsk->delays->blkio_delay; 156 d->blkio_delay_total = (tmp < d->blkio_delay_total) ? 0 : tmp; 157 tmp = d->swapin_delay_total + tsk->delays->swapin_delay; 158 d->swapin_delay_total = (tmp < d->swapin_delay_total) ? 0 : tmp; 159 d->blkio_count += tsk->delays->blkio_count; 160 d->swapin_count += tsk->delays->swapin_count; 161 spin_unlock(&tsk->delays->lock); 162 163 done: 164 spin_unlock(&tsk->delays_lock); 165 return 0; 166 } 167 168 __u64 __delayacct_blkio_ticks(struct task_struct *tsk) 169 { 170 __u64 ret; 171 172 spin_lock(&tsk->delays->lock); 173 ret = nsec_to_clock_t(tsk->delays->blkio_delay + 174 tsk->delays->swapin_delay); 175 spin_unlock(&tsk->delays->lock); 176 return ret; 177 } 178 179