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https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
synced 2025-01-14 17:53:39 +00:00
f65c64f311
Delay accounting can now calculate the average delay of processes, detect
the overall system load, and also record the 'delay max' to identify
potential abnormal delays. However, 'delay min' can help us identify
another useful delay peak. By comparing the difference between 'delay
max' and 'delay min', we can understand the optimization space for
latency, providing a reference for the optimization of latency
performance.
Use case
=========
bash-4.4# ./getdelays -d -t 242
print delayacct stats ON
TGID 242
CPU count real total virtual total delay total delay average delay max delay min
39 156000000 156576579 2111069 0.054ms 0.212296ms 0.031307ms
IO count delay total delay average delay max delay min
0 0 0.000ms 0.000000ms 0.000000ms
SWAP count delay total delay average delay max delay min
0 0 0.000ms 0.000000ms 0.000000ms
RECLAIM count delay total delay average delay max delay min
0 0 0.000ms 0.000000ms 0.000000ms
THRASHING count delay total delay average delay max delay min
0 0 0.000ms 0.000000ms 0.000000ms
COMPACT count delay total delay average delay max delay min
0 0 0.000ms 0.000000ms 0.000000ms
WPCOPY count delay total delay average delay max delay min
156 11215873 0.072ms 0.207403ms 0.033913ms
IRQ count delay total delay average delay max delay min
0 0 0.000ms 0.000000ms 0.000000ms
Link: https://lkml.kernel.org/r/20241220173105906EOdsPhzjMLYNJJBqgz1ga@zte.com.cn
Co-developed-by: Wang Yong <wang.yong12@zte.com.cn>
Signed-off-by: Wang Yong <wang.yong12@zte.com.cn>
Co-developed-by: xu xin <xu.xin16@zte.com.cn>
Signed-off-by: xu xin <xu.xin16@zte.com.cn>
Signed-off-by: Wang Yaxin <wang.yaxin@zte.com.cn>
Co-developed-by: Kun Jiang <jiang.kun2@zte.com.cn>
Signed-off-by: Kun Jiang <jiang.kun2@zte.com.cn>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Fan Yu <fan.yu9@zte.com.cn>
Cc: Peilin He <he.peilin@zte.com.cn>
Cc: tuqiang <tu.qiang35@zte.com.cn>
Cc: ye xingchen <ye.xingchen@zte.com.cn>
Cc: Yunkai Zhang <zhang.yunkai@zte.com.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
325 lines
9.0 KiB
C
325 lines
9.0 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(const 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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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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* accumulator (@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, u64 *max, u64 *min)
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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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if (ns > *max)
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*max = ns;
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if (*min == 0 || ns < *min)
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*min = ns;
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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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&p->delays->blkio_delay_max,
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&p->delays->blkio_delay_min);
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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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d->cpu_delay_max = tsk->sched_info.max_run_delay;
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d->cpu_delay_min = tsk->sched_info.min_run_delay;
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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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d->blkio_delay_max = tsk->delays->blkio_delay_max;
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d->blkio_delay_min = tsk->delays->blkio_delay_min;
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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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d->swapin_delay_max = tsk->delays->swapin_delay_max;
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d->swapin_delay_min = tsk->delays->swapin_delay_min;
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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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d->freepages_delay_max = tsk->delays->freepages_delay_max;
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d->freepages_delay_min = tsk->delays->freepages_delay_min;
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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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d->thrashing_delay_max = tsk->delays->thrashing_delay_max;
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d->thrashing_delay_min = tsk->delays->thrashing_delay_min;
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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->compact_delay_max = tsk->delays->compact_delay_max;
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d->compact_delay_min = tsk->delays->compact_delay_min;
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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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d->wpcopy_delay_max = tsk->delays->wpcopy_delay_max;
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d->wpcopy_delay_min = tsk->delays->wpcopy_delay_min;
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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->irq_delay_max = tsk->delays->irq_delay_max;
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d->irq_delay_min = tsk->delays->irq_delay_min;
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tmp = d->irq_delay_total + tsk->delays->irq_delay;
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d->irq_delay_total = (tmp < d->irq_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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d->irq_count += tsk->delays->irq_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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¤t->delays->freepages_delay_max,
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¤t->delays->freepages_delay_min);
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}
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void __delayacct_thrashing_start(bool *in_thrashing)
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{
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*in_thrashing = !!current->in_thrashing;
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if (*in_thrashing)
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return;
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current->in_thrashing = 1;
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current->delays->thrashing_start = local_clock();
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}
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void __delayacct_thrashing_end(bool *in_thrashing)
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{
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if (*in_thrashing)
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return;
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current->in_thrashing = 0;
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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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¤t->delays->thrashing_delay_max,
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¤t->delays->thrashing_delay_min);
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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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¤t->delays->swapin_delay_max,
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¤t->delays->swapin_delay_min);
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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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¤t->delays->compact_delay_max,
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¤t->delays->compact_delay_min);
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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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¤t->delays->wpcopy_delay_max,
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¤t->delays->wpcopy_delay_min);
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}
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void __delayacct_irq(struct task_struct *task, u32 delta)
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{
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unsigned long flags;
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raw_spin_lock_irqsave(&task->delays->lock, flags);
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task->delays->irq_delay += delta;
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task->delays->irq_count++;
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if (delta > task->delays->irq_delay_max)
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task->delays->irq_delay_max = delta;
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if (delta && (!task->delays->irq_delay_min || delta < task->delays->irq_delay_min))
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task->delays->irq_delay_min = delta;
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raw_spin_unlock_irqrestore(&task->delays->lock, flags);
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}
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