diff options
-rw-r--r-- | Documentation/admin-guide/acpi/cppc_sysfs.rst (renamed from Documentation/acpi/cppc_sysfs.txt) | 71 | ||||
-rw-r--r-- | Documentation/admin-guide/acpi/index.rst | 1 |
2 files changed, 40 insertions, 32 deletions
diff --git a/Documentation/acpi/cppc_sysfs.txt b/Documentation/admin-guide/acpi/cppc_sysfs.rst index f20fb445135d..a4b99afbe331 100644 --- a/Documentation/acpi/cppc_sysfs.txt +++ b/Documentation/admin-guide/acpi/cppc_sysfs.rst | |||
@@ -1,5 +1,11 @@ | |||
1 | .. SPDX-License-Identifier: GPL-2.0 | ||
1 | 2 | ||
2 | Collaborative Processor Performance Control (CPPC) | 3 | ================================================== |
4 | Collaborative Processor Performance Control (CPPC) | ||
5 | ================================================== | ||
6 | |||
7 | CPPC | ||
8 | ==== | ||
3 | 9 | ||
4 | CPPC defined in the ACPI spec describes a mechanism for the OS to manage the | 10 | CPPC defined in the ACPI spec describes a mechanism for the OS to manage the |
5 | performance of a logical processor on a contigious and abstract performance | 11 | performance of a logical processor on a contigious and abstract performance |
@@ -10,31 +16,28 @@ For more details on CPPC please refer to the ACPI specification at: | |||
10 | 16 | ||
11 | http://uefi.org/specifications | 17 | http://uefi.org/specifications |
12 | 18 | ||
13 | Some of the CPPC registers are exposed via sysfs under: | 19 | Some of the CPPC registers are exposed via sysfs under:: |
14 | |||
15 | /sys/devices/system/cpu/cpuX/acpi_cppc/ | ||
16 | |||
17 | for each cpu X | ||
18 | 20 | ||
19 | -------------------------------------------------------------------------------- | 21 | /sys/devices/system/cpu/cpuX/acpi_cppc/ |
20 | 22 | ||
21 | $ ls -lR /sys/devices/system/cpu/cpu0/acpi_cppc/ | 23 | for each cpu X:: |
22 | /sys/devices/system/cpu/cpu0/acpi_cppc/: | ||
23 | total 0 | ||
24 | -r--r--r-- 1 root root 65536 Mar 5 19:38 feedback_ctrs | ||
25 | -r--r--r-- 1 root root 65536 Mar 5 19:38 highest_perf | ||
26 | -r--r--r-- 1 root root 65536 Mar 5 19:38 lowest_freq | ||
27 | -r--r--r-- 1 root root 65536 Mar 5 19:38 lowest_nonlinear_perf | ||
28 | -r--r--r-- 1 root root 65536 Mar 5 19:38 lowest_perf | ||
29 | -r--r--r-- 1 root root 65536 Mar 5 19:38 nominal_freq | ||
30 | -r--r--r-- 1 root root 65536 Mar 5 19:38 nominal_perf | ||
31 | -r--r--r-- 1 root root 65536 Mar 5 19:38 reference_perf | ||
32 | -r--r--r-- 1 root root 65536 Mar 5 19:38 wraparound_time | ||
33 | 24 | ||
34 | -------------------------------------------------------------------------------- | 25 | $ ls -lR /sys/devices/system/cpu/cpu0/acpi_cppc/ |
26 | /sys/devices/system/cpu/cpu0/acpi_cppc/: | ||
27 | total 0 | ||
28 | -r--r--r-- 1 root root 65536 Mar 5 19:38 feedback_ctrs | ||
29 | -r--r--r-- 1 root root 65536 Mar 5 19:38 highest_perf | ||
30 | -r--r--r-- 1 root root 65536 Mar 5 19:38 lowest_freq | ||
31 | -r--r--r-- 1 root root 65536 Mar 5 19:38 lowest_nonlinear_perf | ||
32 | -r--r--r-- 1 root root 65536 Mar 5 19:38 lowest_perf | ||
33 | -r--r--r-- 1 root root 65536 Mar 5 19:38 nominal_freq | ||
34 | -r--r--r-- 1 root root 65536 Mar 5 19:38 nominal_perf | ||
35 | -r--r--r-- 1 root root 65536 Mar 5 19:38 reference_perf | ||
36 | -r--r--r-- 1 root root 65536 Mar 5 19:38 wraparound_time | ||
35 | 37 | ||
36 | * highest_perf : Highest performance of this processor (abstract scale). | 38 | * highest_perf : Highest performance of this processor (abstract scale). |
37 | * nominal_perf : Highest sustained performance of this processor (abstract scale). | 39 | * nominal_perf : Highest sustained performance of this processor |
40 | (abstract scale). | ||
38 | * lowest_nonlinear_perf : Lowest performance of this processor with nonlinear | 41 | * lowest_nonlinear_perf : Lowest performance of this processor with nonlinear |
39 | power savings (abstract scale). | 42 | power savings (abstract scale). |
40 | * lowest_perf : Lowest performance of this processor (abstract scale). | 43 | * lowest_perf : Lowest performance of this processor (abstract scale). |
@@ -48,22 +51,26 @@ total 0 | |||
48 | * feedback_ctrs : Includes both Reference and delivered performance counter. | 51 | * feedback_ctrs : Includes both Reference and delivered performance counter. |
49 | Reference counter ticks up proportional to processor's reference performance. | 52 | Reference counter ticks up proportional to processor's reference performance. |
50 | Delivered counter ticks up proportional to processor's delivered performance. | 53 | Delivered counter ticks up proportional to processor's delivered performance. |
51 | * wraparound_time: Minimum time for the feedback counters to wraparound (seconds). | 54 | * wraparound_time: Minimum time for the feedback counters to wraparound |
55 | (seconds). | ||
52 | * reference_perf : Performance level at which reference performance counter | 56 | * reference_perf : Performance level at which reference performance counter |
53 | accumulates (abstract scale). | 57 | accumulates (abstract scale). |
54 | 58 | ||
55 | -------------------------------------------------------------------------------- | ||
56 | 59 | ||
57 | Computing Average Delivered Performance | 60 | Computing Average Delivered Performance |
61 | ======================================= | ||
62 | |||
63 | Below describes the steps to compute the average performance delivered by | ||
64 | taking two different snapshots of feedback counters at time T1 and T2. | ||
65 | |||
66 | T1: Read feedback_ctrs as fbc_t1 | ||
67 | Wait or run some workload | ||
58 | 68 | ||
59 | Below describes the steps to compute the average performance delivered by taking | 69 | T2: Read feedback_ctrs as fbc_t2 |
60 | two different snapshots of feedback counters at time T1 and T2. | ||
61 | 70 | ||
62 | T1: Read feedback_ctrs as fbc_t1 | 71 | :: |
63 | Wait or run some workload | ||
64 | T2: Read feedback_ctrs as fbc_t2 | ||
65 | 72 | ||
66 | delivered_counter_delta = fbc_t2[del] - fbc_t1[del] | 73 | delivered_counter_delta = fbc_t2[del] - fbc_t1[del] |
67 | reference_counter_delta = fbc_t2[ref] - fbc_t1[ref] | 74 | reference_counter_delta = fbc_t2[ref] - fbc_t1[ref] |
68 | 75 | ||
69 | delivered_perf = (refernce_perf x delivered_counter_delta) / reference_counter_delta | 76 | delivered_perf = (refernce_perf x delivered_counter_delta) / reference_counter_delta |
diff --git a/Documentation/admin-guide/acpi/index.rst b/Documentation/admin-guide/acpi/index.rst index d68e9914c5ff..9049a7b9f065 100644 --- a/Documentation/admin-guide/acpi/index.rst +++ b/Documentation/admin-guide/acpi/index.rst | |||
@@ -10,3 +10,4 @@ the Linux ACPI support. | |||
10 | 10 | ||
11 | initrd_table_override | 11 | initrd_table_override |
12 | dsdt-override | 12 | dsdt-override |
13 | cppc_sysfs | ||