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(task_delay_info, SLAB_PANIC); 35 delayacct_tsk_init(&init_task); 36 } 37 38 void __delayacct_tsk_init(struct task_struct *tsk) 39 { 40 tsk->delays = kmem_cache_zalloc(delayacct_cache, GFP_KERNEL); 41 if (tsk->delays) 42 spin_lock_init(&tsk->delays->lock); 43 } 44 45 /* 46 * Start accounting for a delay statistic using 47 * its starting timestamp (@start) 48 */ 49 50 static inline void delayacct_start(struct timespec *start) 51 { 52 do_posix_clock_monotonic_gettime(start); 53 } 54 55 /* 56 * Finish delay accounting for a statistic using 57 * its timestamps (@start, @end), accumalator (@total) and @count 58 */ 59 60 static void delayacct_end(struct timespec *start, struct timespec *end, 61 u64 *total, u32 *count) 62 { 63 struct timespec ts; 64 s64 ns; 65 unsigned long flags; 66 67 do_posix_clock_monotonic_gettime(end); 68 ts = timespec_sub(*end, *start); 69 ns = timespec_to_ns(&ts); 70 if (ns < 0) 71 return; 72 73 spin_lock_irqsave(¤t->delays->lock, flags); 74 *total += ns; 75 (*count)++; 76 spin_unlock_irqrestore(¤t->delays->lock, flags); 77 } 78 79 void __delayacct_blkio_start(void) 80 { 81 delayacct_start(¤t->delays->blkio_start); 82 } 83 84 void __delayacct_blkio_end(void) 85 { 86 if (current->delays->flags & DELAYACCT_PF_SWAPIN) 87 /* Swapin block I/O */ 88 delayacct_end(¤t->delays->blkio_start, 89 ¤t->delays->blkio_end, 90 ¤t->delays->swapin_delay, 91 ¤t->delays->swapin_count); 92 else /* Other block I/O */ 93 delayacct_end(¤t->delays->blkio_start, 94 ¤t->delays->blkio_end, 95 ¤t->delays->blkio_delay, 96 ¤t->delays->blkio_count); 97 } 98 99 int __delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk) 100 { 101 s64 tmp; 102 unsigned long t1; 103 unsigned long long t2, t3; 104 unsigned long flags; 105 struct timespec ts; 106 107 /* Though tsk->delays accessed later, early exit avoids 108 * unnecessary returning of other data 109 */ 110 if (!tsk->delays) 111 goto done; 112 113 tmp = (s64)d->cpu_run_real_total; 114 cputime_to_timespec(tsk->utime + tsk->stime, &ts); 115 tmp += timespec_to_ns(&ts); 116 d->cpu_run_real_total = (tmp < (s64)d->cpu_run_real_total) ? 0 : tmp; 117 118 tmp = (s64)d->cpu_scaled_run_real_total; 119 cputime_to_timespec(tsk->utimescaled + tsk->stimescaled, &ts); 120 tmp += timespec_to_ns(&ts); 121 d->cpu_scaled_run_real_total = 122 (tmp < (s64)d->cpu_scaled_run_real_total) ? 0 : tmp; 123 124 /* 125 * No locking available for sched_info (and too expensive to add one) 126 * Mitigate by taking snapshot of values 127 */ 128 t1 = tsk->sched_info.pcount; 129 t2 = tsk->sched_info.run_delay; 130 t3 = tsk->sched_info.cpu_time; 131 132 d->cpu_count += t1; 133 134 tmp = (s64)d->cpu_delay_total + t2; 135 d->cpu_delay_total = (tmp < (s64)d->cpu_delay_total) ? 0 : tmp; 136 137 tmp = (s64)d->cpu_run_virtual_total + t3; 138 d->cpu_run_virtual_total = 139 (tmp < (s64)d->cpu_run_virtual_total) ? 0 : tmp; 140 141 /* zero XXX_total, non-zero XXX_count implies XXX stat overflowed */ 142 143 spin_lock_irqsave(&tsk->delays->lock, flags); 144 tmp = d->blkio_delay_total + tsk->delays->blkio_delay; 145 d->blkio_delay_total = (tmp < d->blkio_delay_total) ? 0 : tmp; 146 tmp = d->swapin_delay_total + tsk->delays->swapin_delay; 147 d->swapin_delay_total = (tmp < d->swapin_delay_total) ? 0 : tmp; 148 d->blkio_count += tsk->delays->blkio_count; 149 d->swapin_count += tsk->delays->swapin_count; 150 spin_unlock_irqrestore(&tsk->delays->lock, flags); 151 152 done: 153 return 0; 154 } 155 156 __u64 __delayacct_blkio_ticks(struct task_struct *tsk) 157 { 158 __u64 ret; 159 unsigned long flags; 160 161 spin_lock_irqsave(&tsk->delays->lock, flags); 162 ret = nsec_to_clock_t(tsk->delays->blkio_delay + 163 tsk->delays->swapin_delay); 164 spin_unlock_irqrestore(&tsk->delays->lock, flags); 165 return ret; 166 } 167 168