linux/drivers/cpuidle/governors/ladder.c
Daniel Lezcano b82b6cca48 cpuidle: Invert CPUIDLE_FLAG_TIME_VALID logic
The only place where the time is invalid is when the ACPI_CSTATE_FFH entry
method is not set. Otherwise for all the drivers, the time can be correctly
measured.

Instead of duplicating the CPUIDLE_FLAG_TIME_VALID flag in all the drivers
for all the states, just invert the logic by replacing it by the flag
CPUIDLE_FLAG_TIME_INVALID, hence we can set this flag only for the acpi idle
driver, remove the former flag from all the drivers and invert the logic with
this flag in the different governor.

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2014-11-12 21:17:27 +01:00

196 lines
5.2 KiB
C

/*
* ladder.c - the residency ladder algorithm
*
* Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com>
* Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
* Copyright (C) 2004, 2005 Dominik Brodowski <linux@brodo.de>
*
* (C) 2006-2007 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
* Shaohua Li <shaohua.li@intel.com>
* Adam Belay <abelay@novell.com>
*
* This code is licenced under the GPL.
*/
#include <linux/kernel.h>
#include <linux/cpuidle.h>
#include <linux/pm_qos.h>
#include <linux/module.h>
#include <linux/jiffies.h>
#include <asm/io.h>
#include <asm/uaccess.h>
#define PROMOTION_COUNT 4
#define DEMOTION_COUNT 1
struct ladder_device_state {
struct {
u32 promotion_count;
u32 demotion_count;
u32 promotion_time;
u32 demotion_time;
} threshold;
struct {
int promotion_count;
int demotion_count;
} stats;
};
struct ladder_device {
struct ladder_device_state states[CPUIDLE_STATE_MAX];
int last_state_idx;
};
static DEFINE_PER_CPU(struct ladder_device, ladder_devices);
/**
* ladder_do_selection - prepares private data for a state change
* @ldev: the ladder device
* @old_idx: the current state index
* @new_idx: the new target state index
*/
static inline void ladder_do_selection(struct ladder_device *ldev,
int old_idx, int new_idx)
{
ldev->states[old_idx].stats.promotion_count = 0;
ldev->states[old_idx].stats.demotion_count = 0;
ldev->last_state_idx = new_idx;
}
/**
* ladder_select_state - selects the next state to enter
* @drv: cpuidle driver
* @dev: the CPU
*/
static int ladder_select_state(struct cpuidle_driver *drv,
struct cpuidle_device *dev)
{
struct ladder_device *ldev = this_cpu_ptr(&ladder_devices);
struct ladder_device_state *last_state;
int last_residency, last_idx = ldev->last_state_idx;
int latency_req = pm_qos_request(PM_QOS_CPU_DMA_LATENCY);
/* Special case when user has set very strict latency requirement */
if (unlikely(latency_req == 0)) {
ladder_do_selection(ldev, last_idx, 0);
return 0;
}
last_state = &ldev->states[last_idx];
if (!(drv->states[last_idx].flags & CPUIDLE_FLAG_TIME_INVALID)) {
last_residency = cpuidle_get_last_residency(dev) - \
drv->states[last_idx].exit_latency;
}
else
last_residency = last_state->threshold.promotion_time + 1;
/* consider promotion */
if (last_idx < drv->state_count - 1 &&
!drv->states[last_idx + 1].disabled &&
!dev->states_usage[last_idx + 1].disable &&
last_residency > last_state->threshold.promotion_time &&
drv->states[last_idx + 1].exit_latency <= latency_req) {
last_state->stats.promotion_count++;
last_state->stats.demotion_count = 0;
if (last_state->stats.promotion_count >= last_state->threshold.promotion_count) {
ladder_do_selection(ldev, last_idx, last_idx + 1);
return last_idx + 1;
}
}
/* consider demotion */
if (last_idx > CPUIDLE_DRIVER_STATE_START &&
(drv->states[last_idx].disabled ||
dev->states_usage[last_idx].disable ||
drv->states[last_idx].exit_latency > latency_req)) {
int i;
for (i = last_idx - 1; i > CPUIDLE_DRIVER_STATE_START; i--) {
if (drv->states[i].exit_latency <= latency_req)
break;
}
ladder_do_selection(ldev, last_idx, i);
return i;
}
if (last_idx > CPUIDLE_DRIVER_STATE_START &&
last_residency < last_state->threshold.demotion_time) {
last_state->stats.demotion_count++;
last_state->stats.promotion_count = 0;
if (last_state->stats.demotion_count >= last_state->threshold.demotion_count) {
ladder_do_selection(ldev, last_idx, last_idx - 1);
return last_idx - 1;
}
}
/* otherwise remain at the current state */
return last_idx;
}
/**
* ladder_enable_device - setup for the governor
* @drv: cpuidle driver
* @dev: the CPU
*/
static int ladder_enable_device(struct cpuidle_driver *drv,
struct cpuidle_device *dev)
{
int i;
struct ladder_device *ldev = &per_cpu(ladder_devices, dev->cpu);
struct ladder_device_state *lstate;
struct cpuidle_state *state;
ldev->last_state_idx = CPUIDLE_DRIVER_STATE_START;
for (i = CPUIDLE_DRIVER_STATE_START; i < drv->state_count; i++) {
state = &drv->states[i];
lstate = &ldev->states[i];
lstate->stats.promotion_count = 0;
lstate->stats.demotion_count = 0;
lstate->threshold.promotion_count = PROMOTION_COUNT;
lstate->threshold.demotion_count = DEMOTION_COUNT;
if (i < drv->state_count - 1)
lstate->threshold.promotion_time = state->exit_latency;
if (i > CPUIDLE_DRIVER_STATE_START)
lstate->threshold.demotion_time = state->exit_latency;
}
return 0;
}
/**
* ladder_reflect - update the correct last_state_idx
* @dev: the CPU
* @index: the index of actual state entered
*/
static void ladder_reflect(struct cpuidle_device *dev, int index)
{
struct ladder_device *ldev = this_cpu_ptr(&ladder_devices);
if (index > 0)
ldev->last_state_idx = index;
}
static struct cpuidle_governor ladder_governor = {
.name = "ladder",
.rating = 10,
.enable = ladder_enable_device,
.select = ladder_select_state,
.reflect = ladder_reflect,
.owner = THIS_MODULE,
};
/**
* init_ladder - initializes the governor
*/
static int __init init_ladder(void)
{
return cpuidle_register_governor(&ladder_governor);
}
postcore_initcall(init_ladder);