/* delayacct.c - per-task delay accounting * * Copyright (C) Shailabh Nagar, IBM Corp. 2006 * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it would be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See * the GNU General Public License for more details. */ #include <linux/sched.h> #include <linux/slab.h> #include <linux/time.h> #include <linux/sysctl.h> #include <linux/delayacct.h> int delayacct_on __read_mostly = 1; /* Delay accounting turned on/off */ struct kmem_cache *delayacct_cache; static int __init delayacct_setup_disable(char *str) { delayacct_on = 0; return 1; } __setup("nodelayacct", delayacct_setup_disable); void delayacct_init(void) { delayacct_cache = KMEM_CACHE(task_delay_info, SLAB_PANIC); delayacct_tsk_init(&init_task); } void __delayacct_tsk_init(struct task_struct *tsk) { tsk->delays = kmem_cache_zalloc(delayacct_cache, GFP_KERNEL); if (tsk->delays) spin_lock_init(&tsk->delays->lock); } /* * Start accounting for a delay statistic using * its starting timestamp (@start) */ static inline void delayacct_start(struct timespec *start) { do_posix_clock_monotonic_gettime(start); } /* * Finish delay accounting for a statistic using * its timestamps (@start, @end), accumalator (@total) and @count */ static void delayacct_end(struct timespec *start, struct timespec *end, u64 *total, u32 *count) { struct timespec ts; s64 ns; unsigned long flags; do_posix_clock_monotonic_gettime(end); ts = timespec_sub(*end, *start); ns = timespec_to_ns(&ts); if (ns < 0) return; spin_lock_irqsave(¤t->delays->lock, flags); *total += ns; (*count)++; spin_unlock_irqrestore(¤t->delays->lock, flags); } void __delayacct_blkio_start(void) { delayacct_start(¤t->delays->blkio_start); } void __delayacct_blkio_end(void) { if (current->delays->flags & DELAYACCT_PF_SWAPIN) /* Swapin block I/O */ delayacct_end(¤t->delays->blkio_start, ¤t->delays->blkio_end, ¤t->delays->swapin_delay, ¤t->delays->swapin_count); else /* Other block I/O */ delayacct_end(¤t->delays->blkio_start, ¤t->delays->blkio_end, ¤t->delays->blkio_delay, ¤t->delays->blkio_count); } int __delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk) { s64 tmp; struct timespec ts; unsigned long t1,t2,t3; unsigned long flags; /* Though tsk->delays accessed later, early exit avoids * unnecessary returning of other data */ if (!tsk->delays) goto done; tmp = (s64)d->cpu_run_real_total; cputime_to_timespec(tsk->utime + tsk->stime, &ts); tmp += timespec_to_ns(&ts); d->cpu_run_real_total = (tmp < (s64)d->cpu_run_real_total) ? 0 : tmp; /* * No locking available for sched_info (and too expensive to add one) * Mitigate by taking snapshot of values */ t1 = tsk->sched_info.pcnt; t2 = tsk->sched_info.run_delay; t3 = tsk->sched_info.cpu_time; d->cpu_count += t1; jiffies_to_timespec(t2, &ts); tmp = (s64)d->cpu_delay_total + timespec_to_ns(&ts); d->cpu_delay_total = (tmp < (s64)d->cpu_delay_total) ? 0 : tmp; tmp = (s64)d->cpu_run_virtual_total + (s64)jiffies_to_usecs(t3) * 1000; d->cpu_run_virtual_total = (tmp < (s64)d->cpu_run_virtual_total) ? 0 : tmp; /* zero XXX_total, non-zero XXX_count implies XXX stat overflowed */ spin_lock_irqsave(&tsk->delays->lock, flags); tmp = d->blkio_delay_total + tsk->delays->blkio_delay; d->blkio_delay_total = (tmp < d->blkio_delay_total) ? 0 : tmp; tmp = d->swapin_delay_total + tsk->delays->swapin_delay; d->swapin_delay_total = (tmp < d->swapin_delay_total) ? 0 : tmp; d->blkio_count += tsk->delays->blkio_count; d->swapin_count += tsk->delays->swapin_count; spin_unlock_irqrestore(&tsk->delays->lock, flags); done: return 0; } __u64 __delayacct_blkio_ticks(struct task_struct *tsk) { __u64 ret; unsigned long flags; spin_lock_irqsave(&tsk->delays->lock, flags); ret = nsec_to_clock_t(tsk->delays->blkio_delay + tsk->delays->swapin_delay); spin_unlock_irqrestore(&tsk->delays->lock, flags); return ret; }