big.little cluster not exposed?

[LMM]

Hi,
  I've just tested with stress-ng with ubuntu and mainline kernel 5.0, and here is what I obtained :

Code:

stress-ng: info:  [3111] dispatching hogs: 1 cpu
stress-ng: info:  [3111] cache allocate: using built-in defaults as unable to determine cache details
stress-ng: info:  [3111] successful run completed in 10.09s
stress-ng: info:  [3111] stressor       bogo ops real time  usr time  sys time   bogo ops/s   bogo ops/s
stress-ng: info:  [3111]                           (secs)    (secs)    (secs)   (real time) (usr+sys time)
stress-ng: info:  [3111] cpu                 576     10.08     10.08      0.00        57.12        57.14

I did it several times and the results are quite similar.

To force the use of A53, I use taskset -c <CPUID>, the CPUID is 0->3 for A53 and 4->5 for A72, I obtained 28

Code:

stress-ng: info:  [3157] dispatching hogs: 1 cpu
stress-ng: info:  [3157] cache allocate: using built-in defaults as unable to determine cache details
stress-ng: info:  [3157] successful run completed in 10.09s
stress-ng: info:  [3157] stressor       bogo ops real time  usr time  sys time   bogo ops/s   bogo ops/s
stress-ng: info:  [3157]                           (secs)    (secs)    (secs)   (real time) (usr+sys time)
stress-ng: info:  [3157] cpu                 285     10.09     10.07      0.00        28.25        28.30

Note that the kernel >4.15 includes the spectre correction which may slightly lower the performances.

Concerning the lpddr4, there is a specific driver file *.bin see : https://wiki.pine64.org/index.php/ROCKPr..._Developer
but do not know how to use them. If you have an idea, tell me because I am very interrested.

Best regards.
LMM