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212 lines
5.4 KiB
212 lines
5.4 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* delayacct.c - per-task delay accounting |
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* |
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* Copyright (C) Shailabh Nagar, IBM Corp. 2006 |
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*/ |
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#include <linux/sched.h> |
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#include <linux/sched/task.h> |
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#include <linux/sched/cputime.h> |
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#include <linux/sched/clock.h> |
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#include <linux/slab.h> |
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#include <linux/taskstats.h> |
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#include <linux/sysctl.h> |
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#include <linux/delayacct.h> |
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#include <linux/module.h> |
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DEFINE_STATIC_KEY_FALSE(delayacct_key); |
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int delayacct_on __read_mostly; /* Delay accounting turned on/off */ |
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struct kmem_cache *delayacct_cache; |
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static void set_delayacct(bool enabled) |
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{ |
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if (enabled) { |
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static_branch_enable(&delayacct_key); |
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delayacct_on = 1; |
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} else { |
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delayacct_on = 0; |
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static_branch_disable(&delayacct_key); |
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} |
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} |
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static int __init delayacct_setup_enable(char *str) |
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{ |
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delayacct_on = 1; |
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return 1; |
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} |
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__setup("delayacct", delayacct_setup_enable); |
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void delayacct_init(void) |
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{ |
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delayacct_cache = KMEM_CACHE(task_delay_info, SLAB_PANIC|SLAB_ACCOUNT); |
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delayacct_tsk_init(&init_task); |
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set_delayacct(delayacct_on); |
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} |
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#ifdef CONFIG_PROC_SYSCTL |
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int sysctl_delayacct(struct ctl_table *table, int write, void *buffer, |
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size_t *lenp, loff_t *ppos) |
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{ |
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int state = delayacct_on; |
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struct ctl_table t; |
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int err; |
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if (write && !capable(CAP_SYS_ADMIN)) |
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return -EPERM; |
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t = *table; |
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t.data = &state; |
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err = proc_dointvec_minmax(&t, write, buffer, lenp, ppos); |
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if (err < 0) |
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return err; |
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if (write) |
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set_delayacct(state); |
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return err; |
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} |
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#endif |
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void __delayacct_tsk_init(struct task_struct *tsk) |
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{ |
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tsk->delays = kmem_cache_zalloc(delayacct_cache, GFP_KERNEL); |
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if (tsk->delays) |
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raw_spin_lock_init(&tsk->delays->lock); |
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} |
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/* |
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* Finish delay accounting for a statistic using its timestamps (@start), |
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* accumalator (@total) and @count |
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*/ |
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static void delayacct_end(raw_spinlock_t *lock, u64 *start, u64 *total, u32 *count) |
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{ |
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s64 ns = local_clock() - *start; |
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unsigned long flags; |
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if (ns > 0) { |
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raw_spin_lock_irqsave(lock, flags); |
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*total += ns; |
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(*count)++; |
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raw_spin_unlock_irqrestore(lock, flags); |
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} |
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} |
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void __delayacct_blkio_start(void) |
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{ |
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current->delays->blkio_start = local_clock(); |
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} |
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/* |
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* We cannot rely on the `current` macro, as we haven't yet switched back to |
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* the process being woken. |
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*/ |
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void __delayacct_blkio_end(struct task_struct *p) |
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{ |
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struct task_delay_info *delays = p->delays; |
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u64 *total; |
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u32 *count; |
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if (p->delays->flags & DELAYACCT_PF_SWAPIN) { |
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total = &delays->swapin_delay; |
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count = &delays->swapin_count; |
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} else { |
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total = &delays->blkio_delay; |
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count = &delays->blkio_count; |
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} |
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delayacct_end(&delays->lock, &delays->blkio_start, total, count); |
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} |
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int delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk) |
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{ |
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u64 utime, stime, stimescaled, utimescaled; |
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unsigned long long t2, t3; |
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unsigned long flags, t1; |
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s64 tmp; |
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task_cputime(tsk, &utime, &stime); |
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tmp = (s64)d->cpu_run_real_total; |
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tmp += utime + stime; |
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d->cpu_run_real_total = (tmp < (s64)d->cpu_run_real_total) ? 0 : tmp; |
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task_cputime_scaled(tsk, &utimescaled, &stimescaled); |
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tmp = (s64)d->cpu_scaled_run_real_total; |
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tmp += utimescaled + stimescaled; |
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d->cpu_scaled_run_real_total = |
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(tmp < (s64)d->cpu_scaled_run_real_total) ? 0 : tmp; |
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/* |
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* No locking available for sched_info (and too expensive to add one) |
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* Mitigate by taking snapshot of values |
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*/ |
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t1 = tsk->sched_info.pcount; |
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t2 = tsk->sched_info.run_delay; |
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t3 = tsk->se.sum_exec_runtime; |
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d->cpu_count += t1; |
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tmp = (s64)d->cpu_delay_total + t2; |
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d->cpu_delay_total = (tmp < (s64)d->cpu_delay_total) ? 0 : tmp; |
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tmp = (s64)d->cpu_run_virtual_total + t3; |
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d->cpu_run_virtual_total = |
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(tmp < (s64)d->cpu_run_virtual_total) ? 0 : tmp; |
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if (!tsk->delays) |
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return 0; |
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/* zero XXX_total, non-zero XXX_count implies XXX stat overflowed */ |
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raw_spin_lock_irqsave(&tsk->delays->lock, flags); |
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tmp = d->blkio_delay_total + tsk->delays->blkio_delay; |
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d->blkio_delay_total = (tmp < d->blkio_delay_total) ? 0 : tmp; |
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tmp = d->swapin_delay_total + tsk->delays->swapin_delay; |
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d->swapin_delay_total = (tmp < d->swapin_delay_total) ? 0 : tmp; |
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tmp = d->freepages_delay_total + tsk->delays->freepages_delay; |
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d->freepages_delay_total = (tmp < d->freepages_delay_total) ? 0 : tmp; |
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tmp = d->thrashing_delay_total + tsk->delays->thrashing_delay; |
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d->thrashing_delay_total = (tmp < d->thrashing_delay_total) ? 0 : tmp; |
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d->blkio_count += tsk->delays->blkio_count; |
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d->swapin_count += tsk->delays->swapin_count; |
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d->freepages_count += tsk->delays->freepages_count; |
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d->thrashing_count += tsk->delays->thrashing_count; |
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raw_spin_unlock_irqrestore(&tsk->delays->lock, flags); |
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return 0; |
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} |
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__u64 __delayacct_blkio_ticks(struct task_struct *tsk) |
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{ |
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__u64 ret; |
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unsigned long flags; |
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raw_spin_lock_irqsave(&tsk->delays->lock, flags); |
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ret = nsec_to_clock_t(tsk->delays->blkio_delay + |
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tsk->delays->swapin_delay); |
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raw_spin_unlock_irqrestore(&tsk->delays->lock, flags); |
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return ret; |
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} |
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void __delayacct_freepages_start(void) |
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{ |
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current->delays->freepages_start = local_clock(); |
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} |
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void __delayacct_freepages_end(void) |
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{ |
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delayacct_end(¤t->delays->lock, |
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¤t->delays->freepages_start, |
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¤t->delays->freepages_delay, |
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¤t->delays->freepages_count); |
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} |
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void __delayacct_thrashing_start(void) |
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{ |
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current->delays->thrashing_start = local_clock(); |
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} |
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void __delayacct_thrashing_end(void) |
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{ |
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delayacct_end(¤t->delays->lock, |
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¤t->delays->thrashing_start, |
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¤t->delays->thrashing_delay, |
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¤t->delays->thrashing_count); |
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}
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