alistair23-linux/drivers/cpufreq/cpufreq_governor.c
Andreas Schwab 8636fd280e cpufreq: fix jiffies/cputime mixup in conservative/ondemand governors
The function get_cpu_idle_time_jiffy in both the conservative and
ondemand governors use jiffies_to_usecs to convert a cputime value to
usecs which gives the wrong value on architectures where cputime and
jiffies use different units.  Only matters if NO_HZ is disabled, since
otherwise get_cpu_idle_time_us should already return a valid value, and
get_cpu_idle_time_jiffy isn't actually called.

Signed-off-by: Andreas Schwab <schwab@linux-m68k.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2012-11-15 00:33:07 +01:00

53 lines
1.4 KiB
C

/*
* drivers/cpufreq/cpufreq_governor.c
*
* CPUFREQ governors common code
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <asm/cputime.h>
#include <linux/export.h>
#include <linux/kernel_stat.h>
#include <linux/tick.h>
#include <linux/types.h>
/*
* Code picked from earlier governer implementations
*/
static inline u64 get_cpu_idle_time_jiffy(unsigned int cpu, u64 *wall)
{
u64 idle_time;
u64 cur_wall_time;
u64 busy_time;
cur_wall_time = jiffies64_to_cputime64(get_jiffies_64());
busy_time = kcpustat_cpu(cpu).cpustat[CPUTIME_USER];
busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_SYSTEM];
busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_IRQ];
busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_SOFTIRQ];
busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_STEAL];
busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_NICE];
idle_time = cur_wall_time - busy_time;
if (wall)
*wall = cputime_to_usecs(cur_wall_time);
return cputime_to_usecs(idle_time);
}
cputime64_t get_cpu_idle_time(unsigned int cpu, cputime64_t *wall)
{
u64 idle_time = get_cpu_idle_time_us(cpu, NULL);
if (idle_time == -1ULL)
return get_cpu_idle_time_jiffy(cpu, wall);
else
idle_time += get_cpu_iowait_time_us(cpu, wall);
return idle_time;
}
EXPORT_SYMBOL_GPL(get_cpu_idle_time);