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authorMark Gross <mgross@linux.intel.com>2008-02-04 22:30:08 -0800
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2008-02-05 09:44:22 -0800
commitd82b35186eaa816267f044bd70cc0acb3c7971a3 (patch)
treee8de56c122fd8040086e974895afbb8299045c0f /drivers/cpuidle
parent4ef7229ffa93695e346d510b871452811509ea65 (diff)
downloadlwn-d82b35186eaa816267f044bd70cc0acb3c7971a3.tar.gz
lwn-d82b35186eaa816267f044bd70cc0acb3c7971a3.zip
pm qos infrastructure and interface
The following patch is a generalization of the latency.c implementation done by Arjan last year. It provides infrastructure for more than one parameter, and exposes a user mode interface for processes to register pm_qos expectations of processes. This interface provides a kernel and user mode interface for registering performance expectations by drivers, subsystems and user space applications on one of the parameters. Currently we have {cpu_dma_latency, network_latency, network_throughput} as the initial set of pm_qos parameters. The infrastructure exposes multiple misc device nodes one per implemented parameter. The set of parameters implement is defined by pm_qos_power_init() and pm_qos_params.h. This is done because having the available parameters being runtime configurable or changeable from a driver was seen as too easy to abuse. For each parameter a list of performance requirements is maintained along with an aggregated target value. The aggregated target value is updated with changes to the requirement list or elements of the list. Typically the aggregated target value is simply the max or min of the requirement values held in the parameter list elements. >From kernel mode the use of this interface is simple: pm_qos_add_requirement(param_id, name, target_value): Will insert a named element in the list for that identified PM_QOS parameter with the target value. Upon change to this list the new target is recomputed and any registered notifiers are called only if the target value is now different. pm_qos_update_requirement(param_id, name, new_target_value): Will search the list identified by the param_id for the named list element and then update its target value, calling the notification tree if the aggregated target is changed. with that name is already registered. pm_qos_remove_requirement(param_id, name): Will search the identified list for the named element and remove it, after removal it will update the aggregate target and call the notification tree if the target was changed as a result of removing the named requirement. >From user mode: Only processes can register a pm_qos requirement. To provide for automatic cleanup for process the interface requires the process to register its parameter requirements in the following way: To register the default pm_qos target for the specific parameter, the process must open one of /dev/[cpu_dma_latency, network_latency, network_throughput] As long as the device node is held open that process has a registered requirement on the parameter. The name of the requirement is "process_<PID>" derived from the current->pid from within the open system call. To change the requested target value the process needs to write a s32 value to the open device node. This translates to a pm_qos_update_requirement call. To remove the user mode request for a target value simply close the device node. [akpm@linux-foundation.org: fix warnings] [akpm@linux-foundation.org: fix build] [akpm@linux-foundation.org: fix build again] [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: mark 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> Cc: Venki Pallipadi <venkatesh.pallipadi@intel.com> Cc: Adam Belay <abelay@novell.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/cpuidle')
-rw-r--r--drivers/cpuidle/cpuidle.c7
-rw-r--r--drivers/cpuidle/governors/ladder.c5
-rw-r--r--drivers/cpuidle/governors/menu.c4
3 files changed, 10 insertions, 6 deletions
diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
index d2fabe7863a9..2a98d99cbd46 100644
--- a/drivers/cpuidle/cpuidle.c
+++ b/drivers/cpuidle/cpuidle.c
@@ -12,7 +12,7 @@
#include <linux/mutex.h>
#include <linux/sched.h>
#include <linux/notifier.h>
-#include <linux/latency.h>
+#include <linux/pm_qos_params.h>
#include <linux/cpu.h>
#include <linux/cpuidle.h>
@@ -265,7 +265,10 @@ static struct notifier_block cpuidle_latency_notifier = {
.notifier_call = cpuidle_latency_notify,
};
-#define latency_notifier_init(x) do { register_latency_notifier(x); } while (0)
+static inline void latency_notifier_init(struct notifier_block *n)
+{
+ pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n);
+}
#else /* CONFIG_SMP */
diff --git a/drivers/cpuidle/governors/ladder.c b/drivers/cpuidle/governors/ladder.c
index eb666ecae7c9..ba7b9a6b17a1 100644
--- a/drivers/cpuidle/governors/ladder.c
+++ b/drivers/cpuidle/governors/ladder.c
@@ -14,7 +14,7 @@
#include <linux/kernel.h>
#include <linux/cpuidle.h>
-#include <linux/latency.h>
+#include <linux/pm_qos_params.h>
#include <linux/moduleparam.h>
#include <linux/jiffies.h>
@@ -81,7 +81,8 @@ static int ladder_select_state(struct cpuidle_device *dev)
/* consider promotion */
if (last_idx < dev->state_count - 1 &&
last_residency > last_state->threshold.promotion_time &&
- dev->states[last_idx + 1].exit_latency <= system_latency_constraint()) {
+ dev->states[last_idx + 1].exit_latency <=
+ pm_qos_requirement(PM_QOS_CPU_DMA_LATENCY)) {
last_state->stats.promotion_count++;
last_state->stats.demotion_count = 0;
if (last_state->stats.promotion_count >= last_state->threshold.promotion_count) {
diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c
index 299d45c3bdd2..78d77c5dc35c 100644
--- a/drivers/cpuidle/governors/menu.c
+++ b/drivers/cpuidle/governors/menu.c
@@ -8,7 +8,7 @@
#include <linux/kernel.h>
#include <linux/cpuidle.h>
-#include <linux/latency.h>
+#include <linux/pm_qos_params.h>
#include <linux/time.h>
#include <linux/ktime.h>
#include <linux/hrtimer.h>
@@ -48,7 +48,7 @@ static int menu_select(struct cpuidle_device *dev)
break;
if (s->target_residency > data->predicted_us)
break;
- if (s->exit_latency > system_latency_constraint())
+ if (s->exit_latency > pm_qos_requirement(PM_QOS_CPU_DMA_LATENCY))
break;
}