linux.git/drivers/cpuidle/sysfs.c, branch v3.12 Linux kernel source tree cpuidle: Make cpuidle's sysfs directory dynamically allocated 2013-07-15T00:09:47+00:00 Daniel Lezcano daniel.lezcano@linaro.org 2013-06-12T13:08:51+00:00 728ce22b696f9f1404a74d7b2279a65933553a1b The cpuidle sysfs code is designed to have a single instance of per CPU cpuidle directory. It is not possible to remove the sysfs entry and create it again. This is not a problem with the current code but future changes will add CPU hotplug support to enable/disable the device, so it will need to remove the sysfs entry like other subsystems do. That won't be possible without this change, because the kobj is a static object which can't be reused for kobj_init_and_add(). Add cpuidle_device_kobj to be allocated dynamically when adding/removing a sysfs entry which is consistent with the other cpuidle's sysfs entries. An added benefit is that the sysfs code is now more self-contained and the includes needed for sysfs can be moved from cpuidle.h directly into sysfs.c so as to reduce the total number of headers dragged along with cpuidle.h. [rjw: Changelog] Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> 
The cpuidle sysfs code is designed to have a single instance of per
CPU cpuidle directory.  It is not possible to remove the sysfs entry
and create it again.  This is not a problem with the current code but
future changes will add CPU hotplug support to enable/disable the
device, so it will need to remove the sysfs entry like other
subsystems do.  That won't be possible without this change, because
the kobj is a static object which can't be reused for
kobj_init_and_add().

Add cpuidle_device_kobj to be allocated dynamically when
adding/removing a sysfs entry which is consistent with the other
cpuidle's sysfs entries.

An added benefit is that the sysfs code is now more self-contained
and the includes needed for sysfs can be moved from cpuidle.h
directly into sysfs.c so as to reduce the total number of headers
dragged along with cpuidle.h.

[rjw: Changelog]
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
cpuidle: Fix white space to follow CodingStyle 2013-07-15T00:09:47+00:00 Daniel Lezcano daniel.lezcano@linaro.org 2013-06-12T13:08:50+00:00 f89ae89e2790341587f7132f0552c941342115e9 Fix white space in the cpuidle code to follow the rules described in CodingStyle. No changes in behavior should result from this. [rjw: Changelog] Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> 
Fix white space in the cpuidle code to follow the rules described in
CodingStyle.

No changes in behavior should result from this.

[rjw: Changelog]
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
cpuidle: fix number of initialized/destroyed states 2013-01-11T22:20:09+00:00 Krzysztof Mazur krzysiek@podlesie.net 2013-01-11T22:20:09+00:00 392370e7aa387185349946d29a0e17b918e51ae6 Commit bf4d1b5ddb78f86078ac6ae0415802d5f0c68f92 (cpuidle: support multiple drivers) changed the number of initialized state kobjects in cpuidle_add_state_sysfs() from device->state_count to drv->state_count, but left device->state_count in cpuidle_remove_state_sysfs(). The values of these two fields may be different, in which case a NULL pointer dereference may happen in cpuidle_remove_state_sysfs(), for example. Fix this problem by making cpuidle_add_state_sysfs() use device->state_count too (which restores the original behavior of it). [rjw: Changelog] Signed-off-by: Krzysztof Mazur <krzysiek@podlesie.net> Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> 
Commit bf4d1b5ddb78f86078ac6ae0415802d5f0c68f92 (cpuidle: support
multiple drivers) changed the number of initialized state kobjects
in cpuidle_add_state_sysfs() from device->state_count to
drv->state_count, but left device->state_count in
cpuidle_remove_state_sysfs().  The values of these two fields may be
different, in which case a NULL pointer dereference may happen in
cpuidle_remove_state_sysfs(), for example.  Fix this problem by making
cpuidle_add_state_sysfs() use device->state_count too (which restores
the original behavior of it).

[rjw: Changelog]
Signed-off-by: Krzysztof Mazur <krzysiek@podlesie.net>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
cpuidle: support multiple drivers 2012-11-14T23:34:23+00:00 Daniel Lezcano daniel.lezcano@linaro.org 2012-10-31T16:44:48+00:00 bf4d1b5ddb78f86078ac6ae0415802d5f0c68f92 With the tegra3 and the big.LITTLE [1] new architectures, several cpus with different characteristics (latencies and states) can co-exists on the system. The cpuidle framework has the limitation of handling only identical cpus. This patch removes this limitation by introducing the multiple driver support for cpuidle. This option is configurable at compile time and should be enabled for the architectures mentioned above. So there is no impact for the other platforms if the option is disabled. The option defaults to 'n'. Note the multiple drivers support is also compatible with the existing drivers, even if just one driver is needed, all the cpu will be tied to this driver using an extra small chunk of processor memory. The multiple driver support use a per-cpu driver pointer instead of a global variable and the accessor to this variable are done from a cpu context. In order to keep the compatibility with the existing drivers, the function 'cpuidle_register_driver' and 'cpuidle_unregister_driver' will register the specified driver for all the cpus. The semantic for the output of /sys/devices/system/cpu/cpuidle/current_driver remains the same except the driver name will be related to the current cpu. The /sys/devices/system/cpu/cpu[0-9]/cpuidle/driver/name files are added allowing to read the per cpu driver name. [1] http://lwn.net/Articles/481055/ Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org> Acked-by: Peter De Schrijver <pdeschrijver@nvidia.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> 
With the tegra3 and the big.LITTLE [1] new architectures, several cpus
with different characteristics (latencies and states) can co-exists on the
system.

The cpuidle framework has the limitation of handling only identical cpus.

This patch removes this limitation by introducing the multiple driver support
for cpuidle.

This option is configurable at compile time and should be enabled for the
architectures mentioned above. So there is no impact for the other platforms
if the option is disabled. The option defaults to 'n'. Note the multiple drivers
support is also compatible with the existing drivers, even if just one driver is
needed, all the cpu will be tied to this driver using an extra small chunk of
processor memory.

The multiple driver support use a per-cpu driver pointer instead of a global
variable and the accessor to this variable are done from a cpu context.

In order to keep the compatibility with the existing drivers, the function
'cpuidle_register_driver' and 'cpuidle_unregister_driver' will register
the specified driver for all the cpus.

The semantic for the output of /sys/devices/system/cpu/cpuidle/current_driver
remains the same except the driver name will be related to the current cpu.

The /sys/devices/system/cpu/cpu[0-9]/cpuidle/driver/name files are added
allowing to read the per cpu driver name.

[1] http://lwn.net/Articles/481055/

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Acked-by: Peter De Schrijver <pdeschrijver@nvidia.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
cpuidle: fixup device.h header in cpuidle.h 2012-11-14T23:34:21+00:00 Daniel Lezcano daniel.lezcano@linaro.org 2012-10-31T00:09:02+00:00 8f3e9953e1e4ae5c11e2e880e7d85c03c0180613 The "struct device" is only used in sysfs.c. The other .c files including the private header "cpuidle.h" do not need to pull the entire headers tree from there as they don't manipulate the "struct device". This patch fixes this by moving the header inclusion to sysfs.c and adding a forward declaration for the struct device. The number of lines generated by the preprocesor: Without this patch : 17269 loc With this patch : 16446 loc Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> 
The "struct device" is only used in sysfs.c.

The other .c files including the private header "cpuidle.h"
do not need to pull the entire headers tree from there as they
don't manipulate the "struct device".

This patch fixes this by moving the header inclusion to sysfs.c
and adding a forward declaration for the struct device.

The number of lines generated by the preprocesor:
Without this patch : 17269 loc
With this patch : 16446 loc

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
cpuidle / sysfs: move structure declaration into the sysfs.c file 2012-11-14T23:34:21+00:00 Daniel Lezcano daniel.lezcano@linaro.org 2012-10-31T00:05:16+00:00 349631e0e411fefa2fed7e0a30b97704562dbd6b The structure cpuidle_state_kobj is not used anywhere except in the sysfs.c file. The definition of this structure is not needed in the cpuidle header file. This patch moves it to the sysfs.c file in order to encapsulate the code a bit more. Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> 
The structure cpuidle_state_kobj is not used anywhere except
in the sysfs.c file. The definition of this structure is not
needed in the cpuidle header file. This patch moves it to the
sysfs.c file in order to encapsulate the code a bit more.

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
cpuidle / sysfs: move kobj initialization in the syfs file 2012-11-14T23:34:19+00:00 Daniel Lezcano daniel.lezcano@linaro.org 2012-10-26T10:26:32+00:00 e45a00d679a788217f35ee4214a32d6d1924160b Move the kobj initialization and completion in the sysfs.c and encapsulate the code more. Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> 
Move the kobj initialization and completion in the sysfs.c
and encapsulate the code more.

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
cpuidle / sysfs: change function parameter 2012-11-14T23:34:19+00:00 Daniel Lezcano daniel.lezcano@linaro.org 2012-10-26T10:26:24+00:00 1aef40e288acfb3cc28ff77528b34ef66683bed6 The function needs the cpuidle_device which is initially passed to the caller. The current code gets the struct device from the struct cpuidle_device, pass it the cpuidle_add_sysfs function. This function calls per_cpu(cpuidle_devices, cpu) to get the cpuidle_device. This patch pass the cpuidle_device instead and simplify the code. Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> 
The function needs the cpuidle_device which is initially passed to the
caller.

The current code gets the struct device from the struct cpuidle_device,
pass it the cpuidle_add_sysfs function. This function calls
per_cpu(cpuidle_devices, cpu) to get the cpuidle_device.

This patch pass the cpuidle_device instead and simplify the code.

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
cpuidle: move field disable from per-driver to per-cpu 2012-07-03T17:05:31+00:00 ShuoX Liu shuox.liu@intel.com 2012-07-03T17:05:31+00:00 dc7fd275ae60ef8edf952aff2a62462f5d892fd4 Andrew J.Schorr raises a question. When he changes the disable setting on a single CPU, it affects all the other CPUs. Basically, currently, the disable field is per-driver instead of per-cpu. All the C states of the same driver are shared by all CPU in the same machine. The patch changes the `disable' field to per-cpu, so we could set this separately for each cpu. Signed-off-by: ShuoX Liu <shuox.liu@intel.com> Reported-by: Andrew J.Schorr <aschorr@telemetry-investments.com> Reviewed-by: Yanmin Zhang <yanmin_zhang@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> 
Andrew J.Schorr raises a question.  When he changes the disable setting on
a single CPU, it affects all the other CPUs.  Basically, currently, the
disable field is per-driver instead of per-cpu.  All the C states of the
same driver are shared by all CPU in the same machine.

The patch changes the `disable' field to per-cpu, so we could set this
separately for each cpu.

Signed-off-by: ShuoX Liu <shuox.liu@intel.com>
Reported-by: Andrew J.Schorr <aschorr@telemetry-investments.com>
Reviewed-by: Yanmin Zhang <yanmin_zhang@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
cpuidle: add a sysfs entry to disable specific C state for debug purpose. 2012-03-30T05:52:58+00:00 ShuoX Liu shuox.liu@intel.com 2012-03-28T22:19:11+00:00 3a53396b0381ec9d5180fd8fe7a681c8ce95fd9a Some C states of new CPU might be not good. One reason is BIOS might configure them incorrectly. To help developers root cause it quickly, the patch adds a new sysfs entry, so developers could disable specific C state manually. In addition, C state might have much impact on performance tuning, as it takes much time to enter/exit C states, which might delay interrupt processing. With the new debug option, developers could check if a deep C state could impact performance and how much impact it could cause. Also add this option in Documentation/cpuidle/sysfs.txt. [akpm@linux-foundation.org: check kstrtol return value] Signed-off-by: ShuoX Liu <shuox.liu@intel.com> Reviewed-by: Yanmin Zhang <yanmin_zhang@intel.com> Reviewed-and-Tested-by: Deepthi Dharwar <deepthi@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Len Brown <len.brown@intel.com> 
Some C states of new CPU might be not good.  One reason is BIOS might
configure them incorrectly.  To help developers root cause it quickly, the
patch adds a new sysfs entry, so developers could disable specific C state
manually.

In addition, C state might have much impact on performance tuning, as it
takes much time to enter/exit C states, which might delay interrupt
processing.  With the new debug option, developers could check if a deep C
state could impact performance and how much impact it could cause.

Also add this option in Documentation/cpuidle/sysfs.txt.

[akpm@linux-foundation.org: check kstrtol return value]
Signed-off-by: ShuoX Liu <shuox.liu@intel.com>
Reviewed-by: Yanmin Zhang <yanmin_zhang@intel.com>
Reviewed-and-Tested-by: Deepthi Dharwar <deepthi@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Len Brown <len.brown@intel.com>