diff options
| -rw-r--r-- | Documentation/pm_qos_interface.txt | 59 | ||||
| -rw-r--r-- | drivers/cpuidle/cpuidle.c | 7 | ||||
| -rw-r--r-- | drivers/cpuidle/governors/ladder.c | 5 | ||||
| -rw-r--r-- | drivers/cpuidle/governors/menu.c | 4 | ||||
| -rw-r--r-- | include/linux/pm_qos_params.h | 25 | ||||
| -rw-r--r-- | kernel/Makefile | 2 | ||||
| -rw-r--r-- | kernel/pm_qos_params.c | 425 |
7 files changed, 520 insertions, 7 deletions
diff --git a/Documentation/pm_qos_interface.txt b/Documentation/pm_qos_interface.txt new file mode 100644 index 0000000..49adb1a --- /dev/null +++ b/Documentation/pm_qos_interface.txt @@ -0,0 +1,59 @@ +PM quality of Service interface. + +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. + + + diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c index d2fabe7..2a98d99 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 eb666ec..ba7b9a6 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 299d45c..78d77c5 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; } diff --git a/include/linux/pm_qos_params.h b/include/linux/pm_qos_params.h new file mode 100644 index 0000000..2e4e97b --- /dev/null +++ b/include/linux/pm_qos_params.h @@ -0,0 +1,25 @@ +/* interface for the pm_qos_power infrastructure of the linux kernel. + * + * Mark Gross + */ +#include <linux/list.h> +#include <linux/notifier.h> +#include <linux/miscdevice.h> + +#define PM_QOS_RESERVED 0 +#define PM_QOS_CPU_DMA_LATENCY 1 +#define PM_QOS_NETWORK_LATENCY 2 +#define PM_QOS_NETWORK_THROUGHPUT 3 + +#define PM_QOS_NUM_CLASSES 4 +#define PM_QOS_DEFAULT_VALUE -1 + +int pm_qos_add_requirement(int qos, char *name, s32 value); +int pm_qos_update_requirement(int qos, char *name, s32 new_value); +void pm_qos_remove_requirement(int qos, char *name); + +int pm_qos_requirement(int qos); + +int pm_qos_add_notifier(int qos, struct notifier_block *notifier); +int pm_qos_remove_notifier(int qos, struct notifier_block *notifier); + diff --git a/kernel/Makefile b/kernel/Makefile index db9af70..8331243 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -9,7 +9,7 @@ obj-y = sched.o fork.o exec_domain.o panic.o printk.o profile.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 \ - utsname.o notifier.o ksysfs.o + utsname.o notifier.o ksysfs.o pm_qos_params.o obj-$(CONFIG_SYSCTL) += sysctl_check.o obj-$(CONFIG_STACKTRACE) += stacktrace.o diff --git a/kernel/pm_qos_params.c b/kernel/pm_qos_params.c new file mode 100644 index 0000000..0afe32b --- /dev/null +++ b/kernel/pm_qos_params.c @@ -0,0 +1,425 @@ +/* + * This module exposes the interface to kernel space for specifying + * QoS dependencies. It provides infrastructure for registration of: + * + * Dependents on a QoS value : register requirements + * Watchers of QoS value : get notified when target QoS value changes + * + * This QoS design is best effort based. Dependents register their QoS needs. + * Watchers register to keep track of the current QoS needs of the system. + * + * There are 3 basic classes of QoS parameter: latency, timeout, throughput + * each have defined units: + * latency: usec + * timeout: usec <-- currently not used. + * throughput: kbs (kilo byte / sec) + * + * There are lists of pm_qos_objects each one wrapping requirements, notifiers + * + * User mode requirements on a QOS parameter register themselves to the + * subsystem by opening the device node /dev/... and writing there request to + * the node. As long as the process holds a file handle open to the node the + * client continues to be accounted for. Upon file release the usermode + * requirement is removed and a new qos target is computed. This way when the + * requirement that the application has is cleaned up when closes the file + * pointer or exits the pm_qos_object will get an opportunity to clean up. + * + * mark gross mgross@linux.intel.com + */ + +#include <linux/pm_qos_params.h> +#include <linux/sched.h> +#include <linux/spinlock.h> +#include <linux/slab.h> +#include <linux/time.h> +#include <linux/fs.h> +#include <linux/device.h> +#include <linux/miscdevice.h> +#include <linux/string.h> +#include <linux/platform_device.h> +#include <linux/init.h> + +#include <linux/uaccess.h> + +/* + * locking rule: all changes to target_value or requirements or notifiers lists + * or pm_qos_object list and pm_qos_objects need to happen with pm_qos_lock + * held, taken with _irqsave. One lock to rule them all + */ +struct requirement_list { + struct list_head list; + union { + s32 value; + s32 usec; + s32 kbps; + }; + char *name; +}; + +static s32 max_compare(s32 v1, s32 v2); +static s32 min_compare(s32 v1, s32 v2); + +struct pm_qos_object { + struct requirement_list requirements; + struct blocking_notifier_head *notifiers; + struct miscdevice pm_qos_power_miscdev; + char *name; + s32 default_value; + s32 target_value; + s32 (*comparitor)(s32, s32); +}; + +static struct pm_qos_object null_pm_qos; +static BLOCKING_NOTIFIER_HEAD(cpu_dma_lat_notifier); +static struct pm_qos_object cpu_dma_pm_qos = { + .requirements = {LIST_HEAD_INIT(cpu_dma_pm_qos.requirements.list)}, + .notifiers = &cpu_dma_lat_notifier, + .name = "cpu_dma_latency", + .default_value = 2000 * USEC_PER_SEC, + .target_value = 2000 * USEC_PER_SEC, + .comparitor = min_compare +}; + +static BLOCKING_NOTIFIER_HEAD(network_lat_notifier); +static struct pm_qos_object network_lat_pm_qos = { + .requirements = {LIST_HEAD_INIT(network_lat_pm_qos.requirements.list)}, + .notifiers = &network_lat_notifier, + .name = "network_latency", + .default_value = 2000 * USEC_PER_SEC, + .target_value = 2000 * USEC_PER_SEC, + .comparitor = min_compare +}; + + +static BLOCKING_NOTIFIER_HEAD(network_throughput_notifier); +static struct pm_qos_object network_throughput_pm_qos = { + .requirements = + {LIST_HEAD_INIT(network_throughput_pm_qos.requirements.list)}, + .notifiers = &network_throughput_notifier, + .name = "network_throughput", + .default_value = 0, + .target_value = 0, + .comparitor = max_compare +}; + + +static struct pm_qos_object *pm_qos_array[] = { + &null_pm_qos, + &cpu_dma_pm_qos, + &network_lat_pm_qos, + &network_throughput_pm_qos +}; + +static DEFINE_SPINLOCK(pm_qos_lock); + +static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf, + size_t count, loff_t *f_pos); +static int pm_qos_power_open(struct inode *inode, struct file *filp); +static int pm_qos_power_release(struct inode *inode, struct file *filp); + +static const struct file_operations pm_qos_power_fops = { + .write = pm_qos_power_write, + .open = pm_qos_power_open, + .release = pm_qos_power_release, +}; + +/* static helper functions */ +static s32 max_compare(s32 v1, s32 v2) +{ + return max(v1, v2); +} + +static s32 min_compare(s32 v1, s32 v2) +{ + return min(v1, v2); +} + + +static void update_target(int target) +{ + s32 extreme_value; + struct requirement_list *node; + unsigned long flags; + int call_notifier = 0; + + spin_lock_irqsave(&pm_qos_lock, flags); + extreme_value = pm_qos_array[target]->default_value; + list_for_each_entry(node, + &pm_qos_array[target]->requirements.list, list) { + extreme_value = pm_qos_array[target]->comparitor( + extreme_value, node->value); + } + if (pm_qos_array[target]->target_value != extreme_value) { + call_notifier = 1; + pm_qos_array[target]->target_value = extreme_value; + pr_debug(KERN_ERR "new target for qos %d is %d\n", target, + pm_qos_array[target]->target_value); + } + spin_unlock_irqrestore(&pm_qos_lock, flags); + + if (call_notifier) + blocking_notifier_call_chain(pm_qos_array[target]->notifiers, + (unsigned long) extreme_value, NULL); +} + +static int register_pm_qos_misc(struct pm_qos_object *qos) +{ + qos->pm_qos_power_miscdev.minor = MISC_DYNAMIC_MINOR; + qos->pm_qos_power_miscdev.name = qos->name; + qos->pm_qos_power_miscdev.fops = &pm_qos_power_fops; + + return misc_register(&qos->pm_qos_power_miscdev); +} + +static int find_pm_qos_object_by_minor(int minor) +{ + int pm_qos_class; + + for (pm_qos_class = 0; + pm_qos_class < PM_QOS_NUM_CLASSES; pm_qos_class++) { + if (minor == + pm_qos_array[pm_qos_class]->pm_qos_power_miscdev.minor) + return pm_qos_class; + } + return -1; +} + +/** + * pm_qos_requirement - returns current system wide qos expectation + * @pm_qos_class: identification of which qos value is requested + * + * This function returns the current target value in an atomic manner. + */ +int pm_qos_requirement(int pm_qos_class) +{ + int ret_val; + unsigned long flags; + + spin_lock_irqsave(&pm_qos_lock, flags); + ret_val = pm_qos_array[pm_qos_class]->target_value; + spin_unlock_irqrestore(&pm_qos_lock, flags); + + return ret_val; +} +EXPORT_SYMBOL_GPL(pm_qos_requirement); + +/** + * pm_qos_add_requirement - inserts new qos request into the list + * @pm_qos_class: identifies which list of qos request to us + * @name: identifies the request + * @value: defines the qos request + * + * This function inserts a new entry in the pm_qos_class list of requested qos + * performance charactoistics. It recomputes the agregate QoS expectations for + * the pm_qos_class of parrameters. + */ +int pm_qos_add_requirement(int pm_qos_class, char *name, s32 value) +{ + struct requirement_list *dep; + unsigned long flags; + + dep = kzalloc(sizeof(struct requirement_list), GFP_KERNEL); + if (dep) { + if (value == PM_QOS_DEFAULT_VALUE) + dep->value = pm_qos_array[pm_qos_class]->default_value; + else + dep->value = value; + dep->name = kstrdup(name, GFP_KERNEL); + if (!dep->name) + goto cleanup; + + spin_lock_irqsave(&pm_qos_lock, flags); + list_add(&dep->list, + &pm_qos_array[pm_qos_class]->requirements.list); + spin_unlock_irqrestore(&pm_qos_lock, flags); + update_target(pm_qos_class); + + return 0; + } + +cleanup: + kfree(dep); + return -ENOMEM; +} +EXPORT_SYMBOL_GPL(pm_qos_add_requirement); + +/** + * pm_qos_update_requirement - modifies an existing qos request + * @pm_qos_class: identifies which list of qos request to us + * @name: identifies the request + * @value: defines the qos request + * + * Updates an existing qos requierement for the pm_qos_class of parameters along + * with updating the target pm_qos_class value. + * + * If the named request isn't in the lest then no change is made. + */ +int pm_qos_update_requirement(int pm_qos_class, char *name, s32 new_value) +{ + unsigned long flags; + struct requirement_list *node; + int pending_update = 0; + + spin_lock_irqsave(&pm_qos_lock, flags); + list_for_each_entry(node, + &pm_qos_array[pm_qos_class]->requirements.list, list) { + if (strcmp(node->name, name) == 0) { + if (new_value == PM_QOS_DEFAULT_VALUE) + node->value = + pm_qos_array[pm_qos_class]->default_value; + else + node->value = new_value; + pending_update = 1; + break; + } + } + spin_unlock_irqrestore(&pm_qos_lock, flags); + if (pending_update) + update_target(pm_qos_class); + + return 0; +} +EXPORT_SYMBOL_GPL(pm_qos_update_requirement); + +/** + * pm_qos_remove_requirement - modifies an existing qos request + * @pm_qos_class: identifies which list of qos request to us + * @name: identifies the request + * + * Will remove named qos request from pm_qos_class list of parrameters and + * recompute the current target value for the pm_qos_class. + */ +void pm_qos_remove_requirement(int pm_qos_class, char *name) +{ + unsigned long flags; + struct requirement_list *node; + int pending_update = 0; + + spin_lock_irqsave(&pm_qos_lock, flags); + list_for_each_entry(node, + &pm_qos_array[pm_qos_class]->requirements.list, list) { + if (strcmp(node->name, name) == 0) { + kfree(node->name); + list_del(&node->list); + kfree(node); + pending_update = 1; + break; + } + } + spin_unlock_irqrestore(&pm_qos_lock, flags); + if (pending_update) + update_target(pm_qos_class); +} +EXPORT_SYMBOL_GPL(pm_qos_remove_requirement); + +/** + * pm_qos_add_notifier - sets notification entry for changes to target value + * @pm_qos_class: identifies which qos target changes should be notified. + * @notifier: notifier block managed by caller. + * + * will register the notifier into a notification chain that gets called + * uppon changes to the pm_qos_class target value. + */ + int pm_qos_add_notifier(int pm_qos_class, struct notifier_block *notifier) +{ + int retval; + + retval = blocking_notifier_chain_register( + pm_qos_array[pm_qos_class]->notifiers, notifier); + + return retval; +} +EXPORT_SYMBOL_GPL(pm_qos_add_notifier); + +/** + * pm_qos_remove_notifier - deletes notification entry from chain. + * @pm_qos_class: identifies which qos target changes are notified. + * @notifier: notifier block to be removed. + * + * will remove the notifier from the notification chain that gets called + * uppon changes to the pm_qos_class target value. + */ +int pm_qos_remove_notifier(int pm_qos_class, struct notifier_block *notifier) +{ + int retval; + + retval = blocking_notifier_chain_unregister( + pm_qos_array[pm_qos_class]->notifiers, notifier); + + return retval; +} +EXPORT_SYMBOL_GPL(pm_qos_remove_notifier); + +#define PID_NAME_LEN sizeof("process_1234567890") +static char name[PID_NAME_LEN]; + +static int pm_qos_power_open(struct inode *inode, struct file *filp) +{ + int ret; + long pm_qos_class; + + pm_qos_class = find_pm_qos_object_by_minor(iminor(inode)); + if (pm_qos_class >= 0) { + filp->private_data = (void *)pm_qos_class; + sprintf(name, "process_%d", current->pid); + ret = pm_qos_add_requirement(pm_qos_class, name, + PM_QOS_DEFAULT_VALUE); + if (ret >= 0) + return 0; + } + + return -EPERM; +} + +static int pm_qos_power_release(struct inode *inode, struct file *filp) +{ + int pm_qos_class; + + pm_qos_class = (long)filp->private_data; + sprintf(name, "process_%d", current->pid); + pm_qos_remove_requirement(pm_qos_class, name); + + return 0; +} + +static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf, + size_t count, loff_t *f_pos) +{ + s32 value; + int pm_qos_class; + + pm_qos_class = (long)filp->private_data; + if (count != sizeof(s32)) + return -EINVAL; + if (copy_from_user(&value, buf, sizeof(s32))) + return -EFAULT; + sprintf(name, "process_%d", current->pid); + pm_qos_update_requirement(pm_qos_class, name, value); + + return sizeof(s32); +} + + +static int __init pm_qos_power_init(void) +{ + int ret = 0; + + ret = register_pm_qos_misc(&cpu_dma_pm_qos); + if (ret < 0) { + printk(KERN_ERR "pm_qos_param: cpu_dma_latency setup failed\n"); + return ret; + } + ret = register_pm_qos_misc(&network_lat_pm_qos); + if (ret < 0) { + printk(KERN_ERR "pm_qos_param: network_latency setup failed\n"); + return ret; + } + ret = register_pm_qos_misc(&network_throughput_pm_qos); + if (ret < 0) + printk(KERN_ERR + "pm_qos_param: network_throughput setup failed\n"); + + return ret; +} + +late_initcall(pm_qos_power_init); |
