Results: GPGPU Benchmarks
CompuBench Mobile is a benchmark that tests the compute performance of multi-core systems supporting the RenderScript API, which is a component of the Android operating system. The compute API is similar to CUDA or OpenCL, and can distribute parallel tasks across all compute cores, including the CPU and GPU (as of Android 4.2, RenderScript is expanded to run on the GPU, in addition to the CPU of supported systems). On compute-capable GPUs, the benchmark runs on the graphics engine. Otherwise, the tests stress the CPU cores. The sub-tests cover the following categories: Computer Vision (Face Detection), 3D Graphics (Provence - ray tracing), Image Processing (Gaussian Blur, Histogram), Physics (Particle Simulation – 4K), and Throughput (Julia Set, Ambient Occlusion).
All devices tested meet the requirements for RenderScript support: a compute-capable GPU and Android 4.2 or higher.
The Note 3 can pick a familiar face from the crowd quickest. Oppo's N1 with CyanogenMod comes in second and shows that the Snapdragon 600 SoC is a capable computational engine.
Based on their extremely low scores, it appears that the N1 running ColorOS and the Nexus 5 don't leverage their GPUs. Both devices support RenderScript, so either the API is disabled or the included GPU driver doesn’t include support.
The N1 does well in the ray tracing test, tying Samsung's Note 3. Again, the Nexus 5 trails the Note 3 by a significant margin, despite sporting similar hardware. Likewise, the N1 running ColorOS is more than twice as slow as when it’s running CyanogenMod, unable to fully use all of its compute resources.
The Nexus 5 finally gets the memo extolling RenderScript's virtues as it posts the best scores in all three Image Processing sub-tests. The Note 3 falls behind the Nexus 5 with scores similar to the N1 running CyanogenMod. ColorOS, however, still fails to enlist the help of the N1’s Adreno GPU. Apparently, the Gaussian Blur (RS Intrinsic) test ran only on the CPU for all devices, since the ranking is similar to all of the other CPU benchmarks.
In the Physics test, the N1 (CyanogenMod) is back on top, outperforming both Snapdragon 800-based devices. It’s closely followed by the Xiaomi Mi3. Obviously, RenderScript support is broken in ColorOS.
The Nexus 5 dominates the Julia Set Throughput test, showing more than four times the performance of the next-fastest device. After confirming this result with the CompuBenchRS online database, we contacted Kishonti (the benchmark’s developer) for an explanation. Kishonti stated that newer RenderScript drivers enable GPU acceleration for more tasks. The driver for the Nexus 5 apparently enables GPU support for the specific operations performed during the Julia Set test.
The remaining devices appear to run Julia Set solely on the CPU. Oppo's N1 with CyanogenMod utilizes all four of its Krait 300 cores while running this test. ColorOS only uses two of the four CPU cores for Julia Set, which explains why its score is roughly half of the value achieved using CyanogenMod. We saw similar behavior when running the Geekbench 3 Multi-Core benchmark. Clearly, ColorOS has trouble utilizing all four cores under heavy load, limiting the N1 to dual-core-like performance.
