Documentation: cpufreq: load_table: Update load_table debugfs file documentation

This patch add the detailed description of 'load_table' debugfs file to show
collected CPUs load and the change of CPU frequency.

Changes since v6:
- No change

Changes since v5:
- Add description of test case

Change-Id: Ieb4dbb5f76c4d704a7bf94479bfa91cb1b8cdfad
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>

1 files changed, 36 insertions, 4 deletions

diff --git a/Documentation/cpu-freq/cpufreq-stats.txt b/Documentation/cpu-freq/cpufreq-stats.txt
index fc647492e94..f1d97d0324a 100644
--- a/Documentation/cpu-freq/cpufreq-stats.txt
+++ b/Documentation/cpu-freq/cpufreq-stats.txt
@@ -18,10 +18,12 @@ Contents
 1. Introduction
 
 cpufreq-stats is a driver that provides CPU frequency statistics for each CPU.
-These statistics are provided in /sysfs as a bunch of read_only interfaces. This
-interface (when configured) will appear in a separate directory under cpufreq
-in /sysfs (<sysfs root>/devices/system/cpu/cpuX/cpufreq/stats/) for each CPU.
-Various statistics will form read_only files under this directory.
+These statistics are provided in /sysfs and /debugfs as a bunch of read_only
+interfaces. This interface (when configured) will appear in a separate directory
+under cpufreq in below directory list for each CPU. Various statistics will form
+read_only files under this directory.
+- /sysfs (<sysfs root>/devices/system/cpu/cpuX/cpufreq/stats/)
+- /debugfs (<sysfs root>/kernel/debug/cpufreq/cpuX/)
 
 This driver is designed to be independent of any particular cpufreq_driver
 that may be running on your CPU. So, it will work with any cpufreq_driver.
@@ -33,6 +35,7 @@ cpufreq stats provides following statistics (explained in detail below).
 -  time_in_state
 -  total_trans
 -  trans_table
+-  load_table
 
 All the statistics will be from the time the stats driver has been inserted 
 to the time when a read of a particular statistic is done. Obviously, stats 
@@ -95,6 +98,29 @@ contains the actual freq values for each row and column for better readability.
   2800000:         0         0         0         2         0 
 --------------------------------------------------------------------------------
 
+-  load_table
+This gives the collected CPUs data which include measured time, old CPU
+frequency, new CPU frequency and each CPU load. The cat output will have
+"<measured time> <old CPU frequency> <new CPU frequency> <CPUs load> ..." pair
+in each line, which will mean the change of CPU frequency according to CPUs load
+at <measured time>.
+
+--------------------------------------------------------------------------------
+- In case that all CPUs share only one voltage/frequency.
+<mysystem>:/sys/kernel/debug/cpufreq/cpu0 # cat load_table
+Time(ms)   Old Freq(Hz) New Freq(Hz) CPU0 CPU1 CPU2 CPU3
+23820      500000       500000       53   86   2    73
+23920      500000       400000       66   40   0    42
+24020      400000       400000       71   71   10   52
+24120      400000       300000       33   27   45   65
+24220      300000       300000       4    37   71   34
+24320      300000       300000       1    85   38   16
+24420      300000       200000       6    41   15   51
+24520      200000       200000       12   62   1    51
+24620      200000       200000       9    51   0    58
+24720      200000       200000       32   32   11   27
+--------------------------------------------------------------------------------
+
 
 3. Configuring cpufreq-stats
 
@@ -104,6 +130,7 @@ Config Main Menu
 		CPU Frequency scaling  --->
 			[*] CPU Frequency scaling
 			<*>   CPU frequency translation statistics 
+			(10)    Maximum storage size to save CPU load (10-1000)
 			[*]     CPU frequency translation statistics details
 
 
@@ -113,6 +140,11 @@ cpufreq-stats.
 "CPU frequency translation statistics" (CONFIG_CPU_FREQ_STAT) provides the
 basic statistics which includes time_in_state and total_trans.
 
+"Maximum storage size to save CPU load (10-1000)" (depends on CONFIG_CPU_FREQ_
+STAT) indicates the total number of load_table data and provides collected data
+which include old cpu frequency, new cpu frequency and CPUs load. The user can
+determine the storage size of collected CPUs data. The range is from 10 to 1000.
+
 "CPU frequency translation statistics details" (CONFIG_CPU_FREQ_STAT_DETAILS)
 provides fine grained cpufreq stats by trans_table. The reason for having a
 separate config option for trans_table is: