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662ce1dc9c
Delay accounting does not track the delay of write-protect copy. When
tasks trigger many write-protect copys(include COW and unsharing of
anonymous pages[1]), it may spend a amount of time waiting for them. To
get the delay of tasks in write-protect copy, could help users to evaluate
the impact of using KSM or fork() or GUP.
Also update tools/accounting/getdelays.c:
/ # ./getdelays -dl -p 231
print delayacct stats ON
listen forever
PID 231
CPU count real total virtual total delay total delay average
6247 1859000000 2154070021 1674255063 0.268ms
IO count delay total delay average
0 0 0ms
SWAP count delay total delay average
0 0 0ms
RECLAIM count delay total delay average
0 0 0ms
THRASHING count delay total delay average
0 0 0ms
COMPACT count delay total delay average
3 72758 0ms
WPCOPY count delay total delay average
3635 271567604 0ms
[1] commit 31cc5bc4af70("mm: support GUP-triggered unsharing of anonymous pages")
Link: https://lkml.kernel.org/r/20220409014342.2505532-1-yang.yang29@zte.com.cn
Signed-off-by: Yang Yang <yang.yang29@zte.com.cn>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Jiang Xuexin <jiang.xuexin@zte.com.cn>
Reviewed-by: Ran Xiaokai <ran.xiaokai@zte.com.cn>
Reviewed-by: wangyong <wang.yong12@zte.com.cn>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
268 lines
6.8 KiB
C
268 lines
6.8 KiB
C
// 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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static 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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static struct ctl_table kern_delayacct_table[] = {
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{
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.procname = "task_delayacct",
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.data = NULL,
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.maxlen = sizeof(unsigned int),
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.mode = 0644,
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.proc_handler = sysctl_delayacct,
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.extra1 = SYSCTL_ZERO,
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.extra2 = SYSCTL_ONE,
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},
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{ }
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};
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static __init int kernel_delayacct_sysctls_init(void)
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{
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register_sysctl_init("kernel", kern_delayacct_table);
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return 0;
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}
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late_initcall(kernel_delayacct_sysctls_init);
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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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delayacct_end(&p->delays->lock,
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&p->delays->blkio_start,
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&p->delays->blkio_delay,
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&p->delays->blkio_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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tmp = d->compact_delay_total + tsk->delays->compact_delay;
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d->compact_delay_total = (tmp < d->compact_delay_total) ? 0 : tmp;
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tmp = d->wpcopy_delay_total + tsk->delays->wpcopy_delay;
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d->wpcopy_delay_total = (tmp < d->wpcopy_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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d->compact_count += tsk->delays->compact_count;
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d->wpcopy_count += tsk->delays->wpcopy_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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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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void __delayacct_swapin_start(void)
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{
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current->delays->swapin_start = local_clock();
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}
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void __delayacct_swapin_end(void)
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{
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delayacct_end(¤t->delays->lock,
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¤t->delays->swapin_start,
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¤t->delays->swapin_delay,
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¤t->delays->swapin_count);
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}
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void __delayacct_compact_start(void)
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{
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current->delays->compact_start = local_clock();
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}
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void __delayacct_compact_end(void)
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{
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delayacct_end(¤t->delays->lock,
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¤t->delays->compact_start,
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¤t->delays->compact_delay,
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¤t->delays->compact_count);
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}
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void __delayacct_wpcopy_start(void)
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{
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current->delays->wpcopy_start = local_clock();
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}
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void __delayacct_wpcopy_end(void)
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{
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delayacct_end(¤t->delays->lock,
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¤t->delays->wpcopy_start,
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¤t->delays->wpcopy_delay,
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¤t->delays->wpcopy_count);
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}
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