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| author | Lina Iyer <ilina@codeaurora.org> | 2020-09-22 21:34:16 +0300 |
|---|---|---|
| committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2020-09-23 15:10:31 +0300 |
| commit | f49735f4978f479b0de4f50ab217d5a56bc83c55 (patch) | |
| tree | ff16650624327711ecff8d9a6b2b885585dd9245 /Documentation/admin-guide/pm | |
| parent | 70c179b49870929ca183421935415622d30875b5 (diff) | |
| download | linux-f49735f4978f479b0de4f50ab217d5a56bc83c55.tar.xz | |
cpuidle: record state entry rejection statistics
CPUs may fail to enter the chosen idle state if there was a
pending interrupt, causing the cpuidle driver to return an error
value.
Record that and export it via sysfs along with the other idle state
statistics.
This could prove useful in understanding behavior of the governor
and the system during usecases that involve multiple CPUs.
Signed-off-by: Lina Iyer <ilina@codeaurora.org>
[ rjw: Changelog and documentation edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'Documentation/admin-guide/pm')
| -rw-r--r-- | Documentation/admin-guide/pm/cpuidle.rst | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/Documentation/admin-guide/pm/cpuidle.rst b/Documentation/admin-guide/pm/cpuidle.rst index a96a423e3779..830868e526f4 100644 --- a/Documentation/admin-guide/pm/cpuidle.rst +++ b/Documentation/admin-guide/pm/cpuidle.rst @@ -528,6 +528,10 @@ object corresponding to it, as follows: Total number of times the hardware has been asked by the given CPU to enter this idle state. +``rejected`` + Total number of times a request to enter this idle state on the given + CPU was rejected. + The :file:`desc` and :file:`name` files both contain strings. The difference between them is that the name is expected to be more concise, while the description may be longer and it may contain white space or special characters. @@ -572,6 +576,11 @@ particular case. For these reasons, the only reliable way to find out how much time has been spent by the hardware in different idle states supported by it is to use idle state residency counters in the hardware, if available. +Generally, an interrupt received when trying to enter an idle state causes the +idle state entry request to be rejected, in which case the ``CPUIdle`` driver +may return an error code to indicate that this was the case. The :file:`usage` +and :file:`rejected` files report the number of times the given idle state +was entered successfully or rejected, respectively. .. _cpu-pm-qos: |