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authorChangbin Du <changbin.du@gmail.com>2019-04-25 01:53:03 +0800
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2019-04-25 23:07:20 +0200
commit3e57460f007c86476c376a08e31da441cae0b195 (patch)
treef798e311307d9ed3c856798cf53e17d2bba03462 /Documentation/acpi
parent440ebec745dcbc44866f6b19e5145a12d4494a5f (diff)
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Documentation: ACPI: move cppc_sysfs.txt to admin-guide/acpi and convert to reST
This converts the plain text documentation to reStructuredText format and adds it to Sphinx TOC tree. No essential content change. Signed-off-by: Changbin Du <changbin.du@gmail.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'Documentation/acpi')
-rw-r--r--Documentation/acpi/cppc_sysfs.txt69
1 files changed, 0 insertions, 69 deletions
diff --git a/Documentation/acpi/cppc_sysfs.txt b/Documentation/acpi/cppc_sysfs.txt
deleted file mode 100644
index f20fb445135d..000000000000
--- a/Documentation/acpi/cppc_sysfs.txt
+++ /dev/null
@@ -1,69 +0,0 @@
-
- Collaborative Processor Performance Control (CPPC)
-
-CPPC defined in the ACPI spec describes a mechanism for the OS to manage the
-performance of a logical processor on a contigious and abstract performance
-scale. CPPC exposes a set of registers to describe abstract performance scale,
-to request performance levels and to measure per-cpu delivered performance.
-
-For more details on CPPC please refer to the ACPI specification at:
-
-http://uefi.org/specifications
-
-Some of the CPPC registers are exposed via sysfs under:
-
-/sys/devices/system/cpu/cpuX/acpi_cppc/
-
-for each cpu X
-
---------------------------------------------------------------------------------
-
-$ ls -lR /sys/devices/system/cpu/cpu0/acpi_cppc/
-/sys/devices/system/cpu/cpu0/acpi_cppc/:
-total 0
--r--r--r-- 1 root root 65536 Mar 5 19:38 feedback_ctrs
--r--r--r-- 1 root root 65536 Mar 5 19:38 highest_perf
--r--r--r-- 1 root root 65536 Mar 5 19:38 lowest_freq
--r--r--r-- 1 root root 65536 Mar 5 19:38 lowest_nonlinear_perf
--r--r--r-- 1 root root 65536 Mar 5 19:38 lowest_perf
--r--r--r-- 1 root root 65536 Mar 5 19:38 nominal_freq
--r--r--r-- 1 root root 65536 Mar 5 19:38 nominal_perf
--r--r--r-- 1 root root 65536 Mar 5 19:38 reference_perf
--r--r--r-- 1 root root 65536 Mar 5 19:38 wraparound_time
-
---------------------------------------------------------------------------------
-
-* highest_perf : Highest performance of this processor (abstract scale).
-* nominal_perf : Highest sustained performance of this processor (abstract scale).
-* lowest_nonlinear_perf : Lowest performance of this processor with nonlinear
- power savings (abstract scale).
-* lowest_perf : Lowest performance of this processor (abstract scale).
-
-* lowest_freq : CPU frequency corresponding to lowest_perf (in MHz).
-* nominal_freq : CPU frequency corresponding to nominal_perf (in MHz).
- The above frequencies should only be used to report processor performance in
- freqency instead of abstract scale. These values should not be used for any
- functional decisions.
-
-* feedback_ctrs : Includes both Reference and delivered performance counter.
- Reference counter ticks up proportional to processor's reference performance.
- Delivered counter ticks up proportional to processor's delivered performance.
-* wraparound_time: Minimum time for the feedback counters to wraparound (seconds).
-* reference_perf : Performance level at which reference performance counter
- accumulates (abstract scale).
-
---------------------------------------------------------------------------------
-
- Computing Average Delivered Performance
-
-Below describes the steps to compute the average performance delivered by taking
-two different snapshots of feedback counters at time T1 and T2.
-
-T1: Read feedback_ctrs as fbc_t1
- Wait or run some workload
-T2: Read feedback_ctrs as fbc_t2
-
-delivered_counter_delta = fbc_t2[del] - fbc_t1[del]
-reference_counter_delta = fbc_t2[ref] - fbc_t1[ref]
-
-delivered_perf = (refernce_perf x delivered_counter_delta) / reference_counter_delta