2008-08-05 22:01:35 +02:00
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PM Quality Of Service Interface.
|
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>
2008-02-05 07:30:08 +01:00
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This interface provides a kernel and user mode interface for registering
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performance expectations by drivers, subsystems and user space applications on
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one of the parameters.
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2011-10-04 21:54:45 +02:00
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Two different PM QoS frameworks are available:
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1. PM QoS classes for cpu_dma_latency, network_latency, network_throughput.
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2. the per-device PM QoS framework provides the API to manage the per-device latency
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2013-06-21 04:09:15 +02:00
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constraints and PM QoS flags.
|
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>
2008-02-05 07:30:08 +01:00
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2008-08-05 22:01:35 +02:00
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Each parameters have defined units:
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* latency: usec
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* timeout: usec
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* throughput: kbs (kilo bit / sec)
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2011-10-04 21:54:45 +02:00
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1. PM QoS framework
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|
|
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>
2008-02-05 07:30:08 +01:00
|
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The infrastructure exposes multiple misc device nodes one per implemented
|
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parameter. The set of parameters implement is defined by pm_qos_power_init()
|
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and pm_qos_params.h. This is done because having the available parameters
|
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|
being runtime configurable or changeable from a driver was seen as too easy to
|
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abuse.
|
|
|
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|
2010-05-06 01:59:26 +02:00
|
|
|
For each parameter a list of performance requests is maintained along with
|
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>
2008-02-05 07:30:08 +01:00
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an aggregated target value. The aggregated target value is updated with
|
2010-05-06 01:59:26 +02:00
|
|
|
changes to the request list or elements of the list. Typically the
|
|
|
|
aggregated target value is simply the max or min of the request values held
|
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>
2008-02-05 07:30:08 +01:00
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in the parameter list elements.
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2011-10-04 21:54:45 +02:00
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Note: the aggregated target value is implemented as an atomic variable so that
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|
reading the aggregated value does not require any locking mechanism.
|
|
|
|
|
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>
2008-02-05 07:30:08 +01:00
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|
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From kernel mode the use of this interface is simple:
|
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|
2011-10-04 21:54:45 +02:00
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|
void pm_qos_add_request(handle, param_class, target_value):
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Will insert an element into the list for that identified PM QoS class with the
|
2010-05-06 01:59:26 +02:00
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target value. Upon change to this list the new target is recomputed and any
|
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|
|
registered notifiers are called only if the target value is now different.
|
2011-10-04 21:54:45 +02:00
|
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|
Clients of pm_qos need to save the returned handle for future use in other
|
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|
pm_qos API functions.
|
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>
2008-02-05 07:30:08 +01:00
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|
2010-05-06 01:59:26 +02:00
|
|
|
void pm_qos_update_request(handle, new_target_value):
|
|
|
|
Will update the list element pointed to by the handle with the new target value
|
|
|
|
and recompute the new aggregated target, calling the notification tree if the
|
|
|
|
target is changed.
|
|
|
|
|
|
|
|
void pm_qos_remove_request(handle):
|
|
|
|
Will remove the element. After removal it will update the aggregate target and
|
|
|
|
call the notification tree if the target was changed as a result of removing
|
|
|
|
the request.
|
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>
2008-02-05 07:30:08 +01:00
|
|
|
|
2011-10-04 21:54:45 +02:00
|
|
|
int pm_qos_request(param_class):
|
|
|
|
Returns the aggregated value for a given PM QoS class.
|
|
|
|
|
|
|
|
int pm_qos_request_active(handle):
|
|
|
|
Returns if the request is still active, i.e. it has not been removed from a
|
|
|
|
PM QoS class constraints list.
|
|
|
|
|
|
|
|
int pm_qos_add_notifier(param_class, notifier):
|
|
|
|
Adds a notification callback function to the PM QoS class. The callback is
|
|
|
|
called when the aggregated value for the PM QoS class is changed.
|
|
|
|
|
|
|
|
int pm_qos_remove_notifier(int param_class, notifier):
|
|
|
|
Removes the notification callback function for the PM QoS class.
|
|
|
|
|
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>
2008-02-05 07:30:08 +01:00
|
|
|
|
|
|
|
From user mode:
|
2010-05-06 01:59:26 +02:00
|
|
|
Only processes can register a pm_qos request. To provide for automatic
|
|
|
|
cleanup of a process, the interface requires the process to register its
|
|
|
|
parameter requests in the following way:
|
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>
2008-02-05 07:30:08 +01:00
|
|
|
|
|
|
|
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
|
2010-05-06 01:59:26 +02:00
|
|
|
request on the parameter.
|
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>
2008-02-05 07:30:08 +01:00
|
|
|
|
2010-05-06 01:59:26 +02:00
|
|
|
To change the requested target value the process needs to write an s32 value to
|
|
|
|
the open device node. Alternatively the user mode program could write a hex
|
|
|
|
string for the value using 10 char long format e.g. "0x12345678". This
|
|
|
|
translates to a pm_qos_update_request call.
|
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>
2008-02-05 07:30:08 +01:00
|
|
|
|
|
|
|
To remove the user mode request for a target value simply close the device
|
|
|
|
node.
|
|
|
|
|
|
|
|
|
2013-06-21 04:09:15 +02:00
|
|
|
2. PM QoS per-device latency and flags framework
|
|
|
|
|
PM / QoS: Introcuce latency tolerance device PM QoS type
Add a new latency tolerance device PM QoS type to be use for
specifying active state (RPM_ACTIVE) memory access (DMA) latency
tolerance requirements for devices. It may be used to prevent
hardware from choosing overly aggressive energy-saving operation
modes (causing too much latency to appear) for the whole platform.
This feature reqiures hardware support, so it only will be
available for devices having a new .set_latency_tolerance()
callback in struct dev_pm_info populated, in which case the
routine pointed to by it should implement whatever is necessary
to transfer the effective requirement value to the hardware.
Whenever the effective latency tolerance changes for the device,
its .set_latency_tolerance() callback will be executed and the
effective value will be passed to it. If that value is negative,
which means that the list of latency tolerance requirements for
the device is empty, the callback is expected to switch the
underlying hardware latency tolerance control mechanism to an
autonomous mode if available. If that value is PM_QOS_LATENCY_ANY,
in turn, and the hardware supports a special "no requirement"
setting, the callback is expected to use it. That allows software
to prevent the hardware from automatically updating the device's
latency tolerance in response to its power state changes (e.g. during
transitions from D3cold to D0), which generally may be done in the
autonomous latency tolerance control mode.
If .set_latency_tolerance() is present for the device, a new
pm_qos_latency_tolerance_us attribute will be present in the
devivce's power directory in sysfs. Then, user space can use
that attribute to specify its latency tolerance requirement for
the device, if any. Writing "any" to it means "no requirement, but
do not let the hardware control latency tolerance" and writing
"auto" to it allows the hardware to be switched to the autonomous
mode if there are no other requirements from the kernel side in the
device's list.
This changeset includes a fix from Mika Westerberg.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2014-02-11 00:35:38 +01:00
|
|
|
For each device, there are three lists of PM QoS requests. Two of them are
|
|
|
|
maintained along with the aggregated targets of resume latency and active
|
|
|
|
state latency tolerance (in microseconds) and the third one is for PM QoS flags.
|
|
|
|
Values are updated in response to changes of the request list.
|
2013-06-21 04:09:15 +02:00
|
|
|
|
PM / QoS: Introcuce latency tolerance device PM QoS type
Add a new latency tolerance device PM QoS type to be use for
specifying active state (RPM_ACTIVE) memory access (DMA) latency
tolerance requirements for devices. It may be used to prevent
hardware from choosing overly aggressive energy-saving operation
modes (causing too much latency to appear) for the whole platform.
This feature reqiures hardware support, so it only will be
available for devices having a new .set_latency_tolerance()
callback in struct dev_pm_info populated, in which case the
routine pointed to by it should implement whatever is necessary
to transfer the effective requirement value to the hardware.
Whenever the effective latency tolerance changes for the device,
its .set_latency_tolerance() callback will be executed and the
effective value will be passed to it. If that value is negative,
which means that the list of latency tolerance requirements for
the device is empty, the callback is expected to switch the
underlying hardware latency tolerance control mechanism to an
autonomous mode if available. If that value is PM_QOS_LATENCY_ANY,
in turn, and the hardware supports a special "no requirement"
setting, the callback is expected to use it. That allows software
to prevent the hardware from automatically updating the device's
latency tolerance in response to its power state changes (e.g. during
transitions from D3cold to D0), which generally may be done in the
autonomous latency tolerance control mode.
If .set_latency_tolerance() is present for the device, a new
pm_qos_latency_tolerance_us attribute will be present in the
devivce's power directory in sysfs. Then, user space can use
that attribute to specify its latency tolerance requirement for
the device, if any. Writing "any" to it means "no requirement, but
do not let the hardware control latency tolerance" and writing
"auto" to it allows the hardware to be switched to the autonomous
mode if there are no other requirements from the kernel side in the
device's list.
This changeset includes a fix from Mika Westerberg.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2014-02-11 00:35:38 +01:00
|
|
|
The target values of resume latency and active state latency tolerance are
|
|
|
|
simply the minimum of the request values held in the parameter list elements.
|
|
|
|
The PM QoS flags aggregate value is a gather (bitwise OR) of all list elements'
|
|
|
|
values. Two device PM QoS flags are defined currently: PM_QOS_FLAG_NO_POWER_OFF
|
|
|
|
and PM_QOS_FLAG_REMOTE_WAKEUP.
|
2011-10-04 21:54:45 +02:00
|
|
|
|
PM / QoS: Introcuce latency tolerance device PM QoS type
Add a new latency tolerance device PM QoS type to be use for
specifying active state (RPM_ACTIVE) memory access (DMA) latency
tolerance requirements for devices. It may be used to prevent
hardware from choosing overly aggressive energy-saving operation
modes (causing too much latency to appear) for the whole platform.
This feature reqiures hardware support, so it only will be
available for devices having a new .set_latency_tolerance()
callback in struct dev_pm_info populated, in which case the
routine pointed to by it should implement whatever is necessary
to transfer the effective requirement value to the hardware.
Whenever the effective latency tolerance changes for the device,
its .set_latency_tolerance() callback will be executed and the
effective value will be passed to it. If that value is negative,
which means that the list of latency tolerance requirements for
the device is empty, the callback is expected to switch the
underlying hardware latency tolerance control mechanism to an
autonomous mode if available. If that value is PM_QOS_LATENCY_ANY,
in turn, and the hardware supports a special "no requirement"
setting, the callback is expected to use it. That allows software
to prevent the hardware from automatically updating the device's
latency tolerance in response to its power state changes (e.g. during
transitions from D3cold to D0), which generally may be done in the
autonomous latency tolerance control mode.
If .set_latency_tolerance() is present for the device, a new
pm_qos_latency_tolerance_us attribute will be present in the
devivce's power directory in sysfs. Then, user space can use
that attribute to specify its latency tolerance requirement for
the device, if any. Writing "any" to it means "no requirement, but
do not let the hardware control latency tolerance" and writing
"auto" to it allows the hardware to be switched to the autonomous
mode if there are no other requirements from the kernel side in the
device's list.
This changeset includes a fix from Mika Westerberg.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2014-02-11 00:35:38 +01:00
|
|
|
Note: The aggregated target values are implemented in such a way that reading
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the aggregated value does not require any locking mechanism.
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2011-10-04 21:54:45 +02:00
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From kernel mode the use of this interface is the following:
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2012-10-23 01:09:12 +02:00
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int dev_pm_qos_add_request(device, handle, type, value):
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2011-10-04 21:54:45 +02:00
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Will insert an element into the list for that identified device with the
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target value. Upon change to this list the new target is recomputed and any
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registered notifiers are called only if the target value is now different.
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Clients of dev_pm_qos need to save the handle for future use in other
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dev_pm_qos API functions.
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int dev_pm_qos_update_request(handle, new_value):
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Will update the list element pointed to by the handle with the new target value
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and recompute the new aggregated target, calling the notification trees if the
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target is changed.
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int dev_pm_qos_remove_request(handle):
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Will remove the element. After removal it will update the aggregate target and
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call the notification trees if the target was changed as a result of removing
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the request.
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s32 dev_pm_qos_read_value(device):
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Returns the aggregated value for a given device's constraints list.
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2013-06-21 04:09:15 +02:00
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enum pm_qos_flags_status dev_pm_qos_flags(device, mask)
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Check PM QoS flags of the given device against the given mask of flags.
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The meaning of the return values is as follows:
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PM_QOS_FLAGS_ALL: All flags from the mask are set
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PM_QOS_FLAGS_SOME: Some flags from the mask are set
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PM_QOS_FLAGS_NONE: No flags from the mask are set
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PM_QOS_FLAGS_UNDEFINED: The device's PM QoS structure has not been
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initialized or the list of requests is empty.
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2014-02-11 00:36:00 +01:00
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int dev_pm_qos_add_ancestor_request(dev, handle, type, value)
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2013-06-21 04:09:15 +02:00
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Add a PM QoS request for the first direct ancestor of the given device whose
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2014-02-11 00:36:00 +01:00
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power.ignore_children flag is unset (for DEV_PM_QOS_RESUME_LATENCY requests)
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or whose power.set_latency_tolerance callback pointer is not NULL (for
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DEV_PM_QOS_LATENCY_TOLERANCE requests).
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2013-06-21 04:09:15 +02:00
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int dev_pm_qos_expose_latency_limit(device, value)
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2014-02-11 00:35:23 +01:00
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Add a request to the device's PM QoS list of resume latency constraints and
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create a sysfs attribute pm_qos_resume_latency_us under the device's power
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directory allowing user space to manipulate that request.
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2013-06-21 04:09:15 +02:00
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void dev_pm_qos_hide_latency_limit(device)
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Drop the request added by dev_pm_qos_expose_latency_limit() from the device's
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2014-02-11 00:35:23 +01:00
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PM QoS list of resume latency constraints and remove sysfs attribute
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pm_qos_resume_latency_us from the device's power directory.
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2013-06-21 04:09:15 +02:00
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int dev_pm_qos_expose_flags(device, value)
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Add a request to the device's PM QoS list of flags and create sysfs attributes
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pm_qos_no_power_off and pm_qos_remote_wakeup under the device's power directory
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allowing user space to change these flags' value.
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void dev_pm_qos_hide_flags(device)
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Drop the request added by dev_pm_qos_expose_flags() from the device's PM QoS list
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of flags and remove sysfs attributes pm_qos_no_power_off and pm_qos_remote_wakeup
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under the device's power directory.
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2011-10-04 21:54:45 +02:00
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Notification mechanisms:
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The per-device PM QoS framework has 2 different and distinct notification trees:
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a per-device notification tree and a global notification tree.
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int dev_pm_qos_add_notifier(device, notifier):
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Adds a notification callback function for the device.
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The callback is called when the aggregated value of the device constraints list
|
2014-02-11 00:35:23 +01:00
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is changed (for resume latency device PM QoS only).
|
2011-10-04 21:54:45 +02:00
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int dev_pm_qos_remove_notifier(device, notifier):
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Removes the notification callback function for the device.
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int dev_pm_qos_add_global_notifier(notifier):
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Adds a notification callback function in the global notification tree of the
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framework.
|
2014-02-11 00:35:23 +01:00
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The callback is called when the aggregated value for any device is changed
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(for resume latency device PM QoS only).
|
2011-10-04 21:54:45 +02:00
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int dev_pm_qos_remove_global_notifier(notifier):
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Removes the notification callback function from the global notification tree
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of the framework.
|
PM / QoS: Introcuce latency tolerance device PM QoS type
Add a new latency tolerance device PM QoS type to be use for
specifying active state (RPM_ACTIVE) memory access (DMA) latency
tolerance requirements for devices. It may be used to prevent
hardware from choosing overly aggressive energy-saving operation
modes (causing too much latency to appear) for the whole platform.
This feature reqiures hardware support, so it only will be
available for devices having a new .set_latency_tolerance()
callback in struct dev_pm_info populated, in which case the
routine pointed to by it should implement whatever is necessary
to transfer the effective requirement value to the hardware.
Whenever the effective latency tolerance changes for the device,
its .set_latency_tolerance() callback will be executed and the
effective value will be passed to it. If that value is negative,
which means that the list of latency tolerance requirements for
the device is empty, the callback is expected to switch the
underlying hardware latency tolerance control mechanism to an
autonomous mode if available. If that value is PM_QOS_LATENCY_ANY,
in turn, and the hardware supports a special "no requirement"
setting, the callback is expected to use it. That allows software
to prevent the hardware from automatically updating the device's
latency tolerance in response to its power state changes (e.g. during
transitions from D3cold to D0), which generally may be done in the
autonomous latency tolerance control mode.
If .set_latency_tolerance() is present for the device, a new
pm_qos_latency_tolerance_us attribute will be present in the
devivce's power directory in sysfs. Then, user space can use
that attribute to specify its latency tolerance requirement for
the device, if any. Writing "any" to it means "no requirement, but
do not let the hardware control latency tolerance" and writing
"auto" to it allows the hardware to be switched to the autonomous
mode if there are no other requirements from the kernel side in the
device's list.
This changeset includes a fix from Mika Westerberg.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2014-02-11 00:35:38 +01:00
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Active state latency tolerance
|
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This device PM QoS type is used to support systems in which hardware may switch
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to energy-saving operation modes on the fly. In those systems, if the operation
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mode chosen by the hardware attempts to save energy in an overly aggressive way,
|
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it may cause excess latencies to be visible to software, causing it to miss
|
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certain protocol requirements or target frame or sample rates etc.
|
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If there is a latency tolerance control mechanism for a given device available
|
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|
|
to software, the .set_latency_tolerance callback in that device's dev_pm_info
|
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|
|
structure should be populated. The routine pointed to by it is should implement
|
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|
whatever is necessary to transfer the effective requirement value to the
|
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|
hardware.
|
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|
Whenever the effective latency tolerance changes for the device, its
|
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|
|
.set_latency_tolerance() callback will be executed and the effective value will
|
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|
|
be passed to it. If that value is negative, which means that the list of
|
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|
|
latency tolerance requirements for the device is empty, the callback is expected
|
|
|
|
to switch the underlying hardware latency tolerance control mechanism to an
|
|
|
|
autonomous mode if available. If that value is PM_QOS_LATENCY_ANY, in turn, and
|
|
|
|
the hardware supports a special "no requirement" setting, the callback is
|
|
|
|
expected to use it. That allows software to prevent the hardware from
|
|
|
|
automatically updating the device's latency tolerance in response to its power
|
|
|
|
state changes (e.g. during transitions from D3cold to D0), which generally may
|
|
|
|
be done in the autonomous latency tolerance control mode.
|
|
|
|
|
|
|
|
If .set_latency_tolerance() is present for the device, sysfs attribute
|
|
|
|
pm_qos_latency_tolerance_us will be present in the devivce's power directory.
|
|
|
|
Then, user space can use that attribute to specify its latency tolerance
|
|
|
|
requirement for the device, if any. Writing "any" to it means "no requirement,
|
|
|
|
but do not let the hardware control latency tolerance" and writing "auto" to it
|
|
|
|
allows the hardware to be switched to the autonomous mode if there are no other
|
|
|
|
requirements from the kernel side in the device's list.
|
|
|
|
|
|
|
|
Kernel code can use the functions described above along with the
|
|
|
|
DEV_PM_QOS_LATENCY_TOLERANCE device PM QoS type to add, remove and update
|
|
|
|
latency tolerance requirements for devices.
|