[RESEARCH] Overclock on Qcom useless due to screened SoC's

Some weeks ago @Quarx told me that he tried to overclock his MotoG. At a first look it works. The system is stable and cpuinfo apps show 1.9GHZ.
BUT: there isn't any performance change. Then I checked it on my device(Xiaomi Mi2) - exactly the same result.
I watched a video about Nexus4 overclock: https://www.youtube.com/watch?v=96hsPe-JH2M
As you can see there isn't any change, too(the minor differences are just random).

Then Quarx found a very interesting commit in MotoG's kernel log:
https://github.com/Quarx2k/kernel-moto-g/commit/ed82c3f26ec4a7ab39a436647643bdaf71dcb67a
The message tells us, that QCOM devices normally are "screened" which basically means, that if your max freq is 1.2GHZ, it doesn't matter what you change in the kernel source. it will always be 1.2GHZ even if it shows 100GHZ because the SoC is limiting that.

There are some older SoC's with adreno 2xx which seem to be overclockable without any problems.
But all new SoCs seem to be screened which prevents overclocking.

Some more tests of other devices and SoC's would be helpful.

scy1192 said:

I'd recommend you get a buttload of single-thread Linpack benchmarks at different frequencies and do some statistical analysis. Maybe make a Google Form where you can input Device, Frequency, and MFLOPS

Linpack because it's exclusively CPU, doesn't vary much between devices of the same model, and scales nicely with frequency.

Click to expand...

Click to collapse

I think Linpack isn't reliable enough because it's completed too fast. For me it takes 1-2s to complete and the result variate's very much.
Sth like Antutu(only the CPU score) with performance governor and maybe even on a clean install would be better.

BryanByteZ said:

So how we can really test it? test in game to see if FPS get more high? I really dont believe that is just a placebo effect, in my kernel with 1.5Ghz I really feel the speed and will test when i finish the OC of 1.8Ghz.

Click to expand...

Click to collapse

well I only said that linpack looks unreliable. Antutu or other cpu intensive benchmarks should work just fine. Just ignore gpu benchmarks, because the gpu is definitely overclockable.