What is the default CPU Freq governor of the SAMSUNG GALAXY S4 GT-I9500 Octacore version? I have been playing around with CPUFreq governors of the octacore version of the Samsung Galaxy S4 and I forgot what was the default governor device was configured to operate at by Samsung?
The default governor on the GT-I9500 is called "ondemand-sec". I'm running the XXUEMJ9 firmware (Android 4.3). It's a modified version of the ondemand governor. Here is a listing in /sys/devices/system/cpu/cpufreq:

root@ja3g:/sys/devices/system/cpu/cpufreq # ls -al
drwxr-xr-x    5 0        0                0 Nov 14 12:38 .
drwxr-xr-x    9 0        0                0 Nov 14 12:38 ..
drwxr-xr-x    2 0        0                0 Nov 14 12:38 iks-cpufreq
drwxr-xr-x    2 0        0                0 Nov 14 12:38 ondemand
drwxrwxrwx    2 0        0                0 Nov 14 12:39 ondemand-sec

root@ja3g:/sys/devices/system/cpu/cpu0/cpufreq # cat scaling_governor          
ondemand-sec


Frequency Mappings

As for which frequency activates which cores, I can't remember if you can query it through sysfs, but I do remember:


Below 600 Mhz, only the A7 cores are active, and they run at a 2x factor. For instance, at 400 Mhz, the A7 cores are actually running at 800 Mhz.
Above 600 Mhz, only the A15 cores are active, and they run at a 1x factor. For instance, at 1.2 Ghz, the A15 cores are actually running at 1.2 Ghz.


The frequency mapping can be found in the kernel sources at drivers/cpufreq/exynos-ikcs-cpufreq.c, around line ~56:

#define ACTUAL_FREQ(x, cur) ((cur == CA7) ? (x) &lt;&lt; 1 : (x))
#define VIRT_FREQ(x, cur) ((cur == CA7) ? (x) &gt;&gt; 1 : (x))


The first line finds the actual frequency of the core. If the current core is an A7, then we perform a bitshift on the "virtual frequency" by 1 to the left. This is in effect a multiplication by 2. 

Much of the rest of the code deals with querying the supported CPU frequencies of each kind of core and merging them to give you the resulting cpufreq table (see cpufreq_merge_tables function around line 197).

More info on how this can be found on this set of slides by Linaro. 

Core Status

You can check which cores are active using a device node at /dev/bL_status.

root@ja3g:/dev # cat bL_status
        0 1 2 3 L2 CCI
[A15]   0 0 0 0  0
[A7]    1 1 1 1  1


The above output indicates that only the A7 cores are active.