[Nook Color Android Development] Divine_Madcat:
So, for all us CM7 users, there have recently been alot of questions as to why there is such a disparity between the stock CM7 kernel, and the 1.1Ghz kernel, given both are made by the same person (dalingrin). Really, there are two questions -

1) Why is the quadrant score different between the kernels?

2) How does this equate to real-world use?

To help answer #1, i went ahead and purchased a copy of Quadrant Advanced. The advanced version lets me run the bench offline (helpful at work ;)), and also shows each piece of the score (the important part, as seen in the results). this breakdown shows where the difference is.

But to answer #2, I have to go well beyond Quadrant, and look at many different benches. I tried to find a variety of both system and 3D benches in a hope to uncover any problems anywhere. If there is a more widespread problem, it may be uncovered in other benchmarks. So, without further ado, the test system:

CM7- nightly 27, running on eMMC

Stock CM7 Kernel, 925Mhz, Performance Governor

OC CM7 Kernel, 1000Mhz, Performance Governor

OC CM7 Kernel, 1100Mhz, Performance Governor

I kept the gov on performance, to help rule out any differences between governors. Performance runs the CPU at full speed all the time, so it keeps the benches comparable. For every CPU speed/kernel change, i rebooted the system, and ran each bench once in the order listed. And the results!

Stock kernel

CPU @ 925, Performance gov,

Quadrant (First run only):

Total: 1536

CPU: 2504

Mem: 1080

I/O: 3629

2D: 188

3D: 278

Linpack:

12.078Mflops

NenaMark:

16.7 Fps

Benchmark PI (https://market.android.com/details?id=gr.androiddev.BenchmarkP):

Pi found in 1636ms

Antutu System benchmark (https://market.android.com/details?id=com.antutu.ABenchMark):

Total Score: 1675

Memory: 407

CPU Integer: 578

CPU Float: 129

2D Graphics: 100

3D Graphics: 276

Database IO: 10

SD Card Write: 5.0 MB/s

SD Card Read: 12.5 MB/s

An3DBench (https://market.android.com/details?id=com.threed.jpct.bench):

Fillrate ST/MT: 6.21/6.22 MP/s

High object count: 27.03 Fps

Multiple Lights: 40.19 Fps

High polygon count: 19.97 Fps

Keyframe animation: 39.97 Fps

Game level: 30.04 Fps

Total score: 4278

3/16 Overclock Kernel

CPU @1000Mhz, Performance gov

Quadrant (First run only):

Total: 960

CPU: 2693

Mem: 1099

I/O: 522

2D: 202

3D: 286

Linpack:

12.983Mflops

NenaMark:

17.0 Fps

Benchmark PI:

Pi found in 1627ms

Antutu System benchmark :

Total Score: 1832

Memory: 445

CPU Integer: 631

CPU Float: 144

2D Graphics: 109

3D Graphics: 302

Database IO: 20

SD Card Write: 5.8 MB/s

SD Card Read: 12.3 MB/s

An3DBench:

Fillrate ST/MT: 6.23/6.19 MP/sec

High object count: 30.46 fps

Multiple Lights: 39.96 fps

High polygon count: 20.16 fps

Keyframe animation: 40.40 fps

Game level: 30.43 fps

Total score: 4397

CPU @1100Mhz, Performance gov

Quadrant (First run only):

Total: 1001

CPU: 2833

Mem: 1085

I/O: 566

2D: 213

3D: 306

Linpack:

MFlops: 13.917

NenaMark:

16.8 Fps

Benchmark PI:

Pi found in 1460

Antutu System benchmark:

**Would not run at 1100**

Total Score:

Memory:

CPU Integer:

CPU Float:

2D Graphics:

3D Graphics:

Database IO:

SD Card Write:

SD Card Read:

An3DBench :

Fillrate ST/MT: 5.89/6.01

High object count: 17.53 fps

Multiple Lights: 40.22 fps

High polygon count: 20.13 fps

Keyframe animation: 40.37 fps

Game level: 30.44

Total score: 4054

The results speak alot, i think, and yet they don't. The big difference, is that the IO score on Quadrant tanks on the OC kernel, but is fine/better on every other test. Specifically, i noticed that file system writes takes much longer on the OC kernel, than the stock. 3D performance makes obvious gains with increasing clock speed, and other CPU / IO benches show no problem either.

The antutu bench failing at 1.1 is very odd, since my system has never shown any instability at this speed. It crashes almost immediately , where are 1.0Ghz makes it through just fine. Could it be my system is instable? Possibly...

just for the heck of it, i set the gov to interactive, and here is what i got (1100Mhz, OC kernel, Interactive Gov):

Antutu System benchmark:

Total Score: 1089

Memory: 481

CPU Integer: 701

CPU Float: 154

2D Graphics: 101

3D Graphics: 209

Database IO: 10

SD Card Write: 4.9 MB/s

SD Card Read: 10.4 MB/s

who knows....

Thus, I am left with this question: Is the Quadrant bench testing an IO function that no other bench i tried is, or is it testing something in a way no other bench does, and just doesn't like this kernel? Obivously, SOMETHING is going on, becuase the problem is measurable and repeatable. The kernel change showing the problem alludes to a possible issue, but other benches say that the likelyhood of noticing it is minimal.

That said, our device isn't the only one that seems like it has a problem with IO scores: http://androidforums.com/samsung-captivate/136969-quadrant-scores.html

Hopefully, this is a starting point for people, and might even help a dev or two pinpoint what might be happening. I am no expert, but am willing to help where i can.