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linux/drivers/acpi/processor_thermal.c
Andi Kleen 2815ab92ba ACPI: Do cpufreq clamping for throttling per package v2 
On Intel CPUs the processor typically uses the highest frequency
set by any logical CPU. When the system overheats
Linux first forces the frequency to the lowest available one
to lower the temperature.

However this was done only per logical CPU, which means all
logical CPUs in a package would need to go through this before
the frequency is actually lowered.

Worse this delay actually prevents real throttling, because
the real throttle code only proceeds when the lowest frequency
is already reached.

So when a throttle event happens force the lowest frequency
for all CPUs in the package where it happened. The per CPU
state is now kept per package, not per logical CPU. An alternative
would be to do it per cpufreq unit, but since we want to bring
down the temperature of the complete chip it's better
to do it for all.

In principle it may even make sense to do it for all CPUs,
but I kept it on the package for now.

With this change the frequency is actually lowered, which
in terms also allows real throttling to proceed.

I also removed an unnecessary per cpu variable initialization.

v2: Fix package mapping

Cc: <stable@vger.kernel.org>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
2012-03-22 02:16:14 -04:00

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/*
* processor_thermal.c - Passive cooling submodule of the ACPI processor driver
*
* Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com>
* Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
* Copyright (C) 2004 Dominik Brodowski <linux@brodo.de>
* Copyright (C) 2004 Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
* - Added processor hotplug support
*
* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or (at
* your option) any later version.
*
* 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.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
*
* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/cpufreq.h>
#include <asm/uaccess.h>
#include <acpi/acpi_bus.h>
#include <acpi/processor.h>
#include <acpi/acpi_drivers.h>
#define PREFIX "ACPI: "
#define ACPI_PROCESSOR_CLASS "processor"
#define _COMPONENT ACPI_PROCESSOR_COMPONENT
ACPI_MODULE_NAME("processor_thermal");
#ifdef CONFIG_CPU_FREQ
/* If a passive cooling situation is detected, primarily CPUfreq is used, as it
* offers (in most cases) voltage scaling in addition to frequency scaling, and
* thus a cubic (instead of linear) reduction of energy. Also, we allow for
* _any_ cpufreq driver and not only the acpi-cpufreq driver.
*/
#define CPUFREQ_THERMAL_MIN_STEP 0
#define CPUFREQ_THERMAL_MAX_STEP 3
static DEFINE_PER_CPU(unsigned int, cpufreq_thermal_reduction_pctg);
static unsigned int acpi_thermal_cpufreq_is_init = 0;
#define reduction_pctg(cpu) \
per_cpu(cpufreq_thermal_reduction_pctg, phys_package_first_cpu(cpu))
/*
* Emulate "per package data" using per cpu data (which should really be
* provided elsewhere)
*
* Note we can lose a CPU on cpu hotunplug, in this case we forget the state
* temporarily. Fortunately that's not a big issue here (I hope)
*/
static int phys_package_first_cpu(int cpu)
{
int i;
int id = topology_physical_package_id(cpu);
for_each_online_cpu(i)
if (topology_physical_package_id(i) == id)
return i;
return 0;
}
static int cpu_has_cpufreq(unsigned int cpu)
{
struct cpufreq_policy policy;
if (!acpi_thermal_cpufreq_is_init || cpufreq_get_policy(&policy, cpu))
return 0;
return 1;
}
static int acpi_thermal_cpufreq_notifier(struct notifier_block *nb,
unsigned long event, void *data)
{
struct cpufreq_policy *policy = data;
unsigned long max_freq = 0;
if (event != CPUFREQ_ADJUST)
goto out;
max_freq = (
policy->cpuinfo.max_freq *
(100 - reduction_pctg(policy->cpu) * 20)
) / 100;
cpufreq_verify_within_limits(policy, 0, max_freq);
out:
return 0;
}
static struct notifier_block acpi_thermal_cpufreq_notifier_block = {
.notifier_call = acpi_thermal_cpufreq_notifier,
};
static int cpufreq_get_max_state(unsigned int cpu)
{
if (!cpu_has_cpufreq(cpu))
return 0;
return CPUFREQ_THERMAL_MAX_STEP;
}
static int cpufreq_get_cur_state(unsigned int cpu)
{
if (!cpu_has_cpufreq(cpu))
return 0;
return reduction_pctg(cpu);
}
static int cpufreq_set_cur_state(unsigned int cpu, int state)
{
int i;
if (!cpu_has_cpufreq(cpu))
return 0;
reduction_pctg(cpu) = state;
/*
* Update all the CPUs in the same package because they all
* contribute to the temperature and often share the same
* frequency.
*/
for_each_online_cpu(i) {
if (topology_physical_package_id(i) ==
topology_physical_package_id(cpu))
cpufreq_update_policy(i);
}
return 0;
}
void acpi_thermal_cpufreq_init(void)
{
int i;
i = cpufreq_register_notifier(&acpi_thermal_cpufreq_notifier_block,
CPUFREQ_POLICY_NOTIFIER);
if (!i)
acpi_thermal_cpufreq_is_init = 1;
}
void acpi_thermal_cpufreq_exit(void)
{
if (acpi_thermal_cpufreq_is_init)
cpufreq_unregister_notifier
(&acpi_thermal_cpufreq_notifier_block,
CPUFREQ_POLICY_NOTIFIER);
acpi_thermal_cpufreq_is_init = 0;
}
#else /* ! CONFIG_CPU_FREQ */
static int cpufreq_get_max_state(unsigned int cpu)
{
return 0;
}
static int cpufreq_get_cur_state(unsigned int cpu)
{
return 0;
}
static int cpufreq_set_cur_state(unsigned int cpu, int state)
{
return 0;
}
#endif
int acpi_processor_get_limit_info(struct acpi_processor *pr)
{
if (!pr)
return -EINVAL;
if (pr->flags.throttling)
pr->flags.limit = 1;
return 0;
}
/* thermal coolign device callbacks */
static int acpi_processor_max_state(struct acpi_processor *pr)
{
int max_state = 0;
/*
* There exists four states according to
* cpufreq_thermal_reduction_ptg. 0, 1, 2, 3
*/
max_state += cpufreq_get_max_state(pr->id);
if (pr->flags.throttling)
max_state += (pr->throttling.state_count -1);
return max_state;
}
static int
processor_get_max_state(struct thermal_cooling_device *cdev,
unsigned long *state)
{
struct acpi_device *device = cdev->devdata;
struct acpi_processor *pr = acpi_driver_data(device);
if (!device || !pr)
return -EINVAL;
*state = acpi_processor_max_state(pr);
return 0;
}
static int
processor_get_cur_state(struct thermal_cooling_device *cdev,
unsigned long *cur_state)
{
struct acpi_device *device = cdev->devdata;
struct acpi_processor *pr = acpi_driver_data(device);
if (!device || !pr)
return -EINVAL;
*cur_state = cpufreq_get_cur_state(pr->id);
if (pr->flags.throttling)
*cur_state += pr->throttling.state;
return 0;
}
static int
processor_set_cur_state(struct thermal_cooling_device *cdev,
unsigned long state)
{
struct acpi_device *device = cdev->devdata;
struct acpi_processor *pr = acpi_driver_data(device);
int result = 0;
int max_pstate;
if (!device || !pr)
return -EINVAL;
max_pstate = cpufreq_get_max_state(pr->id);
if (state > acpi_processor_max_state(pr))
return -EINVAL;
if (state <= max_pstate) {
if (pr->flags.throttling && pr->throttling.state)
result = acpi_processor_set_throttling(pr, 0, false);
cpufreq_set_cur_state(pr->id, state);
} else {
cpufreq_set_cur_state(pr->id, max_pstate);
result = acpi_processor_set_throttling(pr,
state - max_pstate, false);
}
return result;
}
const struct thermal_cooling_device_ops processor_cooling_ops = {
.get_max_state = processor_get_max_state,
.get_cur_state = processor_get_cur_state,
.set_cur_state = processor_set_cur_state,
};
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