Commit f011e2e2 authored by Mark Gross's avatar Mark Gross Committed by Linus Torvalds
Browse files

latency.c: use QoS infrastructure



Replace latency.c use with pm_qos_params use.
Signed-off-by: default avatarmark gross <mgross@linux.intel.com>
Cc: "John W. Linville" <linville@tuxdriver.com>
Cc: Len Brown <lenb@kernel.org>
Cc: Jaroslav Kysela <perex@suse.cz>
Cc: Takashi Iwai <tiwai@suse.de>
Cc: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent d82b3518
......@@ -38,7 +38,7 @@
#include <linux/dmi.h>
#include <linux/moduleparam.h>
#include <linux/sched.h> /* need_resched() */
#include <linux/latency.h>
#include <linux/pm_qos_params.h>
#include <linux/clockchips.h>
#include <linux/cpuidle.h>
......@@ -648,7 +648,8 @@ static void acpi_processor_idle(void)
if (cx->promotion.state &&
((cx->promotion.state - pr->power.states) <= max_cstate)) {
if (sleep_ticks > cx->promotion.threshold.ticks &&
cx->promotion.state->latency <= system_latency_constraint()) {
cx->promotion.state->latency <=
pm_qos_requirement(PM_QOS_CPU_DMA_LATENCY)) {
cx->promotion.count++;
cx->demotion.count = 0;
if (cx->promotion.count >=
......@@ -692,7 +693,8 @@ static void acpi_processor_idle(void)
* or if the latency of the current state is unacceptable
*/
if ((pr->power.state - pr->power.states) > max_cstate ||
pr->power.state->latency > system_latency_constraint()) {
pr->power.state->latency >
pm_qos_requirement(PM_QOS_CPU_DMA_LATENCY)) {
if (cx->demotion.state)
next_state = cx->demotion.state;
}
......@@ -1200,7 +1202,7 @@ static int acpi_processor_power_seq_show(struct seq_file *seq, void *offset)
"maximum allowed latency: %d usec\n",
pr->power.state ? pr->power.state - pr->power.states : 0,
max_cstate, (unsigned)pr->power.bm_activity,
system_latency_constraint());
pm_qos_requirement(PM_QOS_CPU_DMA_LATENCY));
seq_puts(seq, "states:\n");
......@@ -1718,8 +1720,9 @@ int __cpuinit acpi_processor_power_init(struct acpi_processor *pr,
"ACPI: processor limited to max C-state %d\n",
max_cstate);
first_run++;
#if !defined (CONFIG_CPU_IDLE) && defined (CONFIG_SMP)
register_latency_notifier(&acpi_processor_latency_notifier);
#if !defined(CONFIG_CPU_IDLE) && defined(CONFIG_SMP)
pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY,
&acpi_processor_latency_notifier);
#endif
}
......@@ -1806,7 +1809,8 @@ int acpi_processor_power_exit(struct acpi_processor *pr,
*/
cpu_idle_wait();
#ifdef CONFIG_SMP
unregister_latency_notifier(&acpi_processor_latency_notifier);
pm_qos_remove_notifier(PM_QOS_CPU_DMA_LATENCY,
&acpi_processor_latency_notifier);
#endif
}
#endif
......
......@@ -162,7 +162,7 @@ that only one external action is invoked at a time.
#include <linux/firmware.h>
#include <linux/acpi.h>
#include <linux/ctype.h>
#include <linux/latency.h>
#include <linux/pm_qos_params.h>
#include "ipw2100.h"
......@@ -1701,7 +1701,7 @@ static int ipw2100_up(struct ipw2100_priv *priv, int deferred)
/* the ipw2100 hardware really doesn't want power management delays
* longer than 175usec
*/
modify_acceptable_latency("ipw2100", 175);
pm_qos_update_requirement(PM_QOS_CPU_DMA_LATENCY, "ipw2100", 175);
/* If the interrupt is enabled, turn it off... */
spin_lock_irqsave(&priv->low_lock, flags);
......@@ -1856,7 +1856,8 @@ static void ipw2100_down(struct ipw2100_priv *priv)
ipw2100_disable_interrupts(priv);
spin_unlock_irqrestore(&priv->low_lock, flags);
modify_acceptable_latency("ipw2100", INFINITE_LATENCY);
pm_qos_update_requirement(PM_QOS_CPU_DMA_LATENCY, "ipw2100",
PM_QOS_DEFAULT_VALUE);
/* We have to signal any supplicant if we are disassociating */
if (associated)
......@@ -6554,7 +6555,8 @@ static int __init ipw2100_init(void)
if (ret)
goto out;
set_acceptable_latency("ipw2100", INFINITE_LATENCY);
pm_qos_add_requirement(PM_QOS_CPU_DMA_LATENCY, "ipw2100",
PM_QOS_DEFAULT_VALUE);
#ifdef CONFIG_IPW2100_DEBUG
ipw2100_debug_level = debug;
ret = driver_create_file(&ipw2100_pci_driver.driver,
......@@ -6576,7 +6578,7 @@ static void __exit ipw2100_exit(void)
&driver_attr_debug_level);
#endif
pci_unregister_driver(&ipw2100_pci_driver);
remove_acceptable_latency("ipw2100");
pm_qos_remove_requirement(PM_QOS_CPU_DMA_LATENCY, "ipw2100");
}
module_init(ipw2100_init);
......
/*
* latency.h: Explicit system-wide latency-expectation infrastructure
*
* (C) Copyright 2006 Intel Corporation
* Author: Arjan van de Ven <arjan@linux.intel.com>
*
*/
#ifndef _INCLUDE_GUARD_LATENCY_H_
#define _INCLUDE_GUARD_LATENCY_H_
#include <linux/notifier.h>
void set_acceptable_latency(char *identifier, int usecs);
void modify_acceptable_latency(char *identifier, int usecs);
void remove_acceptable_latency(char *identifier);
void synchronize_acceptable_latency(void);
int system_latency_constraint(void);
int register_latency_notifier(struct notifier_block * nb);
int unregister_latency_notifier(struct notifier_block * nb);
#define INFINITE_LATENCY 1000000
#endif
......@@ -8,7 +8,7 @@ obj-y = sched.o fork.o exec_domain.o panic.o printk.o profile.o \
signal.o sys.o kmod.o workqueue.o pid.o \
rcupdate.o extable.o params.o posix-timers.o \
kthread.o wait.o kfifo.o sys_ni.o posix-cpu-timers.o mutex.o \
hrtimer.o rwsem.o latency.o nsproxy.o srcu.o \
hrtimer.o rwsem.o nsproxy.o srcu.o \
utsname.o notifier.o ksysfs.o pm_qos_params.o
obj-$(CONFIG_SYSCTL) += sysctl_check.o
......
/*
* latency.c: Explicit system-wide latency-expectation infrastructure
*
* The purpose of this infrastructure is to allow device drivers to set
* latency constraint they have and to collect and summarize these
* expectations globally. The cummulated result can then be used by
* power management and similar users to make decisions that have
* tradoffs with a latency component.
*
* An example user of this are the x86 C-states; each higher C state saves
* more power, but has a higher exit latency. For the idle loop power
* code to make a good decision which C-state to use, information about
* acceptable latencies is required.
*
* An example announcer of latency is an audio driver that knowns it
* will get an interrupt when the hardware has 200 usec of samples
* left in the DMA buffer; in that case the driver can set a latency
* constraint of, say, 150 usec.
*
* Multiple drivers can each announce their maximum accepted latency,
* to keep these appart, a string based identifier is used.
*
*
* (C) Copyright 2006 Intel Corporation
* Author: Arjan van de Ven <arjan@linux.intel.com>
*
* 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; version 2
* of the License.
*/
#include <linux/latency.h>
#include <linux/list.h>
#include <linux/spinlock.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/notifier.h>
#include <linux/jiffies.h>
#include <asm/atomic.h>
struct latency_info {
struct list_head list;
int usecs;
char *identifier;
};
/*
* locking rule: all modifications to current_max_latency and
* latency_list need to be done while holding the latency_lock.
* latency_lock needs to be taken _irqsave.
*/
static atomic_t current_max_latency;
static DEFINE_SPINLOCK(latency_lock);
static LIST_HEAD(latency_list);
static BLOCKING_NOTIFIER_HEAD(latency_notifier);
/*
* This function returns the maximum latency allowed, which
* happens to be the minimum of all maximum latencies on the
* list.
*/
static int __find_max_latency(void)
{
int min = INFINITE_LATENCY;
struct latency_info *info;
list_for_each_entry(info, &latency_list, list) {
if (info->usecs < min)
min = info->usecs;
}
return min;
}
/**
* set_acceptable_latency - sets the maximum latency acceptable
* @identifier: string that identifies this driver
* @usecs: maximum acceptable latency for this driver
*
* This function informs the kernel that this device(driver)
* can accept at most usecs latency. This setting is used for
* power management and similar tradeoffs.
*
* This function sleeps and can only be called from process
* context.
* Calling this function with an existing identifier is valid
* and will cause the existing latency setting to be changed.
*/
void set_acceptable_latency(char *identifier, int usecs)
{
struct latency_info *info, *iter;
unsigned long flags;
int found_old = 0;
info = kzalloc(sizeof(struct latency_info), GFP_KERNEL);
if (!info)
return;
info->usecs = usecs;
info->identifier = kstrdup(identifier, GFP_KERNEL);
if (!info->identifier)
goto free_info;
spin_lock_irqsave(&latency_lock, flags);
list_for_each_entry(iter, &latency_list, list) {
if (strcmp(iter->identifier, identifier)==0) {
found_old = 1;
iter->usecs = usecs;
break;
}
}
if (!found_old)
list_add(&info->list, &latency_list);
if (usecs < atomic_read(&current_max_latency))
atomic_set(&current_max_latency, usecs);
spin_unlock_irqrestore(&latency_lock, flags);
blocking_notifier_call_chain(&latency_notifier,
atomic_read(&current_max_latency), NULL);
/*
* if we inserted the new one, we're done; otherwise there was
* an existing one so we need to free the redundant data
*/
if (!found_old)
return;
kfree(info->identifier);
free_info:
kfree(info);
}
EXPORT_SYMBOL_GPL(set_acceptable_latency);
/**
* modify_acceptable_latency - changes the maximum latency acceptable
* @identifier: string that identifies this driver
* @usecs: maximum acceptable latency for this driver
*
* This function informs the kernel that this device(driver)
* can accept at most usecs latency. This setting is used for
* power management and similar tradeoffs.
*
* This function does not sleep and can be called in any context.
* Trying to use a non-existing identifier silently gets ignored.
*
* Due to the atomic nature of this function, the modified latency
* value will only be used for future decisions; past decisions
* can still lead to longer latencies in the near future.
*/
void modify_acceptable_latency(char *identifier, int usecs)
{
struct latency_info *iter;
unsigned long flags;
spin_lock_irqsave(&latency_lock, flags);
list_for_each_entry(iter, &latency_list, list) {
if (strcmp(iter->identifier, identifier) == 0) {
iter->usecs = usecs;
break;
}
}
if (usecs < atomic_read(&current_max_latency))
atomic_set(&current_max_latency, usecs);
spin_unlock_irqrestore(&latency_lock, flags);
}
EXPORT_SYMBOL_GPL(modify_acceptable_latency);
/**
* remove_acceptable_latency - removes the maximum latency acceptable
* @identifier: string that identifies this driver
*
* This function removes a previously set maximum latency setting
* for the driver and frees up any resources associated with the
* bookkeeping needed for this.
*
* This function does not sleep and can be called in any context.
* Trying to use a non-existing identifier silently gets ignored.
*/
void remove_acceptable_latency(char *identifier)
{
unsigned long flags;
int newmax = 0;
struct latency_info *iter, *temp;
spin_lock_irqsave(&latency_lock, flags);
list_for_each_entry_safe(iter, temp, &latency_list, list) {
if (strcmp(iter->identifier, identifier) == 0) {
list_del(&iter->list);
newmax = iter->usecs;
kfree(iter->identifier);
kfree(iter);
break;
}
}
/* If we just deleted the system wide value, we need to
* recalculate with a full search
*/
if (newmax == atomic_read(&current_max_latency)) {
newmax = __find_max_latency();
atomic_set(&current_max_latency, newmax);
}
spin_unlock_irqrestore(&latency_lock, flags);
}
EXPORT_SYMBOL_GPL(remove_acceptable_latency);
/**
* system_latency_constraint - queries the system wide latency maximum
*
* This function returns the system wide maximum latency in
* microseconds.
*
* This function does not sleep and can be called in any context.
*/
int system_latency_constraint(void)
{
return atomic_read(&current_max_latency);
}
EXPORT_SYMBOL_GPL(system_latency_constraint);
/**
* synchronize_acceptable_latency - recalculates all latency decisions
*
* This function will cause a callback to various kernel pieces that
* will make those pieces rethink their latency decisions. This implies
* that if there are overlong latencies in hardware state already, those
* latencies get taken right now. When this call completes no overlong
* latency decisions should be active anymore.
*
* Typical usecase of this is after a modify_acceptable_latency() call,
* which in itself is non-blocking and non-synchronizing.
*
* This function blocks and should not be called with locks held.
*/
void synchronize_acceptable_latency(void)
{
blocking_notifier_call_chain(&latency_notifier,
atomic_read(&current_max_latency), NULL);
}
EXPORT_SYMBOL_GPL(synchronize_acceptable_latency);
/*
* Latency notifier: this notifier gets called when a non-atomic new
* latency value gets set. The expectation nof the caller of the
* non-atomic set is that when the call returns, future latencies
* are within bounds, so the functions on the notifier list are
* expected to take the overlong latencies immediately, inside the
* callback, and not make a overlong latency decision anymore.
*
* The callback gets called when the new latency value is made
* active so system_latency_constraint() returns the new latency.
*/
int register_latency_notifier(struct notifier_block * nb)
{
return blocking_notifier_chain_register(&latency_notifier, nb);
}
EXPORT_SYMBOL_GPL(register_latency_notifier);
int unregister_latency_notifier(struct notifier_block * nb)
{
return blocking_notifier_chain_unregister(&latency_notifier, nb);
}
EXPORT_SYMBOL_GPL(unregister_latency_notifier);
static __init int latency_init(void)
{
atomic_set(&current_max_latency, INFINITE_LATENCY);
/*
* we don't want by default to have longer latencies than 2 ticks,
* since that would cause lost ticks
*/
set_acceptable_latency("kernel", 2*1000000/HZ);
return 0;
}
module_init(latency_init);
......@@ -23,7 +23,7 @@
#include <linux/file.h>
#include <linux/slab.h>
#include <linux/time.h>
#include <linux/latency.h>
#include <linux/pm_qos_params.h>
#include <linux/uio.h>
#include <sound/core.h>
#include <sound/control.h>
......@@ -443,9 +443,11 @@ static int snd_pcm_hw_params(struct snd_pcm_substream *substream,
snd_pcm_timer_resolution_change(substream);
runtime->status->state = SNDRV_PCM_STATE_SETUP;
remove_acceptable_latency(substream->latency_id);
pm_qos_remove_requirement(PM_QOS_CPU_DMA_LATENCY,
substream->latency_id);
if ((usecs = period_to_usecs(runtime)) >= 0)
set_acceptable_latency(substream->latency_id, usecs);
pm_qos_add_requirement(PM_QOS_CPU_DMA_LATENCY,
substream->latency_id, usecs);
return 0;
_error:
/* hardware might be unuseable from this time,
......@@ -505,7 +507,8 @@ static int snd_pcm_hw_free(struct snd_pcm_substream *substream)
if (substream->ops->hw_free)
result = substream->ops->hw_free(substream);
runtime->status->state = SNDRV_PCM_STATE_OPEN;
remove_acceptable_latency(substream->latency_id);
pm_qos_remove_requirement(PM_QOS_CPU_DMA_LATENCY,
substream->latency_id);
return result;
}
......
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