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Diffstat (limited to 'Documentation/acpi/cppc_sysfs.txt')
| -rw-r--r-- | Documentation/acpi/cppc_sysfs.txt | 69 |
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 |