3a53396b03
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>
85 lines
3 KiB
Plaintext
85 lines
3 KiB
Plaintext
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Supporting multiple CPU idle levels in kernel
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cpuidle sysfs
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System global cpuidle related information and tunables are under
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/sys/devices/system/cpu/cpuidle
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The current interfaces in this directory has self-explanatory names:
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* current_driver
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* current_governor_ro
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With cpuidle_sysfs_switch boot option (meant for developer testing)
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following objects are visible instead.
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* current_driver
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* available_governors
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* current_governor
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In this case users can switch the governor at run time by writing
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to current_governor.
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Per logical CPU specific cpuidle information are under
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/sys/devices/system/cpu/cpuX/cpuidle
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for each online cpu X
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--------------------------------------------------------------------------------
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# ls -lR /sys/devices/system/cpu/cpu0/cpuidle/
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/sys/devices/system/cpu/cpu0/cpuidle/:
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total 0
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drwxr-xr-x 2 root root 0 Feb 8 10:42 state0
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drwxr-xr-x 2 root root 0 Feb 8 10:42 state1
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drwxr-xr-x 2 root root 0 Feb 8 10:42 state2
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drwxr-xr-x 2 root root 0 Feb 8 10:42 state3
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/sys/devices/system/cpu/cpu0/cpuidle/state0:
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total 0
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-r--r--r-- 1 root root 4096 Feb 8 10:42 desc
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-rw-r--r-- 1 root root 4096 Feb 8 10:42 disable
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-r--r--r-- 1 root root 4096 Feb 8 10:42 latency
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-r--r--r-- 1 root root 4096 Feb 8 10:42 name
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-r--r--r-- 1 root root 4096 Feb 8 10:42 power
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-r--r--r-- 1 root root 4096 Feb 8 10:42 time
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-r--r--r-- 1 root root 4096 Feb 8 10:42 usage
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/sys/devices/system/cpu/cpu0/cpuidle/state1:
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total 0
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-r--r--r-- 1 root root 4096 Feb 8 10:42 desc
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-rw-r--r-- 1 root root 4096 Feb 8 10:42 disable
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-r--r--r-- 1 root root 4096 Feb 8 10:42 latency
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-r--r--r-- 1 root root 4096 Feb 8 10:42 name
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-r--r--r-- 1 root root 4096 Feb 8 10:42 power
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-r--r--r-- 1 root root 4096 Feb 8 10:42 time
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-r--r--r-- 1 root root 4096 Feb 8 10:42 usage
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/sys/devices/system/cpu/cpu0/cpuidle/state2:
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total 0
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-r--r--r-- 1 root root 4096 Feb 8 10:42 desc
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-rw-r--r-- 1 root root 4096 Feb 8 10:42 disable
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-r--r--r-- 1 root root 4096 Feb 8 10:42 latency
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-r--r--r-- 1 root root 4096 Feb 8 10:42 name
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-r--r--r-- 1 root root 4096 Feb 8 10:42 power
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-r--r--r-- 1 root root 4096 Feb 8 10:42 time
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-r--r--r-- 1 root root 4096 Feb 8 10:42 usage
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/sys/devices/system/cpu/cpu0/cpuidle/state3:
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total 0
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-r--r--r-- 1 root root 4096 Feb 8 10:42 desc
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-rw-r--r-- 1 root root 4096 Feb 8 10:42 disable
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-r--r--r-- 1 root root 4096 Feb 8 10:42 latency
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-r--r--r-- 1 root root 4096 Feb 8 10:42 name
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-r--r--r-- 1 root root 4096 Feb 8 10:42 power
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-r--r--r-- 1 root root 4096 Feb 8 10:42 time
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-r--r--r-- 1 root root 4096 Feb 8 10:42 usage
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--------------------------------------------------------------------------------
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* desc : Small description about the idle state (string)
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* disable : Option to disable this idle state (bool)
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* latency : Latency to exit out of this idle state (in microseconds)
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* name : Name of the idle state (string)
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* power : Power consumed while in this idle state (in milliwatts)
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* time : Total time spent in this idle state (in microseconds)
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* usage : Number of times this state was entered (count)
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