diff options
Diffstat (limited to 'kernel/delayacct.c')
| -rw-r--r-- | kernel/delayacct.c | 178 |
1 files changed, 178 insertions, 0 deletions
diff --git a/kernel/delayacct.c b/kernel/delayacct.c new file mode 100644 index 000000000000..f05392d64267 --- /dev/null +++ b/kernel/delayacct.c @@ -0,0 +1,178 @@ +/* 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; /* Delay accounting turned on/off */ +kmem_cache_t *delayacct_cache; + +static int __init delayacct_setup_enable(char *str) +{ + delayacct_on = 1; + return 1; +} +__setup("delayacct", delayacct_setup_enable); + +void delayacct_init(void) +{ + delayacct_cache = kmem_cache_create("delayacct_cache", + sizeof(struct task_delay_info), + 0, + SLAB_PANIC, + NULL, NULL); + delayacct_tsk_init(&init_task); +} + +void __delayacct_tsk_init(struct task_struct *tsk) +{ + spin_lock_init(&tsk->delays_lock); + /* No need to acquire tsk->delays_lock for allocation here unless + __delayacct_tsk_init called after tsk is attached to tasklist + */ + tsk->delays = kmem_cache_zalloc(delayacct_cache, SLAB_KERNEL); + if (tsk->delays) + spin_lock_init(&tsk->delays->lock); +} + +void __delayacct_tsk_exit(struct task_struct *tsk) +{ + struct task_delay_info *delays = tsk->delays; + spin_lock(&tsk->delays_lock); + tsk->delays = NULL; + spin_unlock(&tsk->delays_lock); + kmem_cache_free(delayacct_cache, delays); +} + +/* + * 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; + + do_posix_clock_monotonic_gettime(end); + ts = timespec_sub(*end, *start); + ns = timespec_to_ns(&ts); + if (ns < 0) + return; + + spin_lock(¤t->delays->lock); + *total += ns; + (*count)++; + spin_unlock(¤t->delays->lock); +} + +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; + + spin_lock(&tsk->delays_lock); + + /* 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(&tsk->delays->lock); + 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(&tsk->delays->lock); + +done: + spin_unlock(&tsk->delays_lock); + return 0; +} + +__u64 __delayacct_blkio_ticks(struct task_struct *tsk) +{ + __u64 ret; + + spin_lock(&tsk->delays->lock); + ret = nsec_to_clock_t(tsk->delays->blkio_delay + + tsk->delays->swapin_delay); + spin_unlock(&tsk->delays->lock); + return ret; +} + |