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/* Copyright (c) 2012, The Linux Foundation. All rights reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 and
* only version 2 as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will 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.
*/
/*
* Scheduler hook for average runqueue determination
*/
#include <linux/module.h>
#include <linux/percpu.h>
#include <linux/hrtimer.h>
#include <linux/sched.h>
#include <linux/math64.h>
static DEFINE_PER_CPU(u64, nr_prod_sum);
static DEFINE_PER_CPU(u64, last_time);
static DEFINE_PER_CPU(u64, nr);
static DEFINE_PER_CPU(unsigned long, iowait_prod_sum);
static DEFINE_PER_CPU(spinlock_t, nr_lock) = __SPIN_LOCK_UNLOCKED(nr_lock);
static u64 last_get_time;
/**
* sched_get_nr_running_avg
* @return: Average nr_running and iowait value since last poll.
* Returns the avg * 100 to return up to two decimal points
* of accuracy.
*
* Obtains the average nr_running value since the last poll.
* This function may not be called concurrently with itself
*/
void sched_get_nr_running_avg(int *avg, int *iowait_avg)
{
int cpu;
u64 curr_time = sched_clock();
s64 diff = (s64) (curr_time - last_get_time);
u64 tmp_avg = 0, tmp_iowait = 0, old_lgt;
bool clk_faulty = 0;
u32 cpumask = 0;
*avg = 0;
*iowait_avg = 0;
if (!diff)
return;
WARN(diff<0, "[sched_get_nr_running_avg] time last:%llu curr:%llu ",
last_get_time, curr_time);
old_lgt = last_get_time;
last_get_time = curr_time;
/* read and reset nr_running counts */
for_each_possible_cpu(cpu) {
unsigned long flags;
spin_lock_irqsave(&per_cpu(nr_lock, cpu), flags);
/* error handling for problematic clock violation */
if ((s64) (curr_time - per_cpu(last_time, cpu) < 0)) {
clk_faulty = 1;
cpumask |= 1 << cpu;
}
/* ////// */
tmp_avg += per_cpu(nr_prod_sum, cpu);
tmp_avg += per_cpu(nr, cpu) * (curr_time - per_cpu(last_time, cpu));
tmp_iowait = per_cpu(iowait_prod_sum, cpu);
tmp_iowait += nr_iowait_cpu(cpu) * (curr_time - per_cpu(last_time, cpu));
per_cpu(last_time, cpu) = curr_time;
per_cpu(nr_prod_sum, cpu) = 0;
per_cpu(iowait_prod_sum, cpu) = 0;
spin_unlock_irqrestore(&per_cpu(nr_lock, cpu), flags);
}
/* error handling for problematic clock violation */
if (clk_faulty) {
*avg = 0;
*iowait_avg = 0;
pr_warn("[%s] **** CPU (0x%08x)clock may unstable !!\n", __func__, cpumask);
return;
}
/* ///// */
*avg = (int)div64_u64(tmp_avg * 100, (u64) diff);
*iowait_avg = (int)div64_u64(tmp_iowait * 100, (u64) diff);
WARN(*avg<0, "[sched_get_nr_running_avg] avg:%d(%llu/%lld), time last:%llu curr:%llu ",
*avg, tmp_avg, diff, old_lgt, curr_time);
if (unlikely(*avg<0))
*avg = 0;
WARN(*iowait_avg<0, "[sched_get_nr_running_avg] iowait_avg:%d(%llu/%lld) time last:%llu curr:%llu ",
*iowait_avg, tmp_iowait, diff, old_lgt, curr_time);
if (unlikely(*iowait_avg<0))
*iowait_avg = 0;
}
EXPORT_SYMBOL(sched_get_nr_running_avg);
/**
* sched_update_nr_prod
* @cpu: The core id of the nr running driver.
* @nr: Updated nr running value for cpu.
* @inc: Whether we are increasing or decreasing the count
* @return: N/A
*
* Update average with latest nr_running value for CPU
*/
void sched_update_nr_prod(int cpu, unsigned long nr_running, bool inc)
{
s64 diff;
u64 curr_time;
unsigned long flags;
spin_lock_irqsave(&per_cpu(nr_lock, cpu), flags);
curr_time = sched_clock();
diff = (s64) (curr_time - per_cpu(last_time, cpu));
/* skip this problematic clock violation */
if (diff < 0) {
spin_unlock_irqrestore(&per_cpu(nr_lock, cpu), flags);
return;
}
/* ////////////////////////////////////// */
per_cpu(last_time, cpu) = curr_time;
per_cpu(nr, cpu) = nr_running + (inc ? 1 : -1);
BUG_ON(per_cpu(nr, cpu) < 0);
per_cpu(nr_prod_sum, cpu) += nr_running * diff;
per_cpu(iowait_prod_sum, cpu) += nr_iowait_cpu(cpu) * diff;
spin_unlock_irqrestore(&per_cpu(nr_lock, cpu), flags);
}
EXPORT_SYMBOL(sched_update_nr_prod);
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