GPU And Gaming Performance
The 5.1 update brings support for OpenGL ES 3.1 to the Nexus 6, which was missing from the initial 5.0 release. Beyond this, I could not find any other changes that should affect GPU performance.
|Benchmark||Nexus 6Android 5.0||Nexus 6Android 5.1||Difference|
|3DMark: Ice Storm Unlimited||Score||23618||21253||-10.01%|
|Basemark X: Medium Quality||Performance||30315||26339||-13.12%|
|Dunes: Offscreen||32.82 fps||28.03 fps||-14.61%|
|Dunes: Onscreen||23.65 fps||23.03 fps||-2.64%|
|Hangar: Offscreen||44.45 fps||38.98 fps||-12.31%|
|Hangar: Onscreen||34.24 fps||31.01 fps||-9.43%|
|Basemark X: High Quality||Performance||20825||19178||-7.91%|
|Dunes: Offscreen||29.04 fps||26.84 fps||-7.59%|
|Dunes: Onscreen||20.56 fps||20.26 fps||-1.46%|
|Hangar: Offscreen||25.76 fps||23.65 fps||-8.17%|
|Hangar: Onscreen||17.38 fps||16.93 fps||-2.59%|
|GFXBench 3.0||Manhattan Offscreen||17.0 fps||18.4 fps||8.89%|
|Manhattan Onscreen||12.0 fps||12.1 fps||0.75%|
|T-Rex Offscreen||37.0 fps||39.1 fps||5.47%|
|T-Rex Onscreen||26.5 fps||27.5 fps||3.88%|
|Alpha Blending Offscreen||10694 MB/s||11344 MB/s||6.08%|
|Alpha Blending Onscreen||9281 MB/s||9755 MB/s||5.10%|
|ALU Offscreen||140.5 fps||141.5 fps||0.75%|
|ALU Onscreen||59.5 fps||59.0 fps||-0.06%|
|Driver Overhead Offscreen||25.0 fps||24 fps||-3.28%|
|Driver Overhead Onscreen||22.0 fps||19.5 fps||-11.01%|
|Fill Offscreen||7334 MTexels/s||7465 MTexels/s||1.79%|
|Fill Onscreen||8474 MTexels/s||8490 MTexels/s||0.19%|
|Render Quality: Standard||2503 mB PSNR||2503 mB PSNR||0.00%|
|Render Quality: High Precision||3633 mB PSNR||3628 mB PSNR||-0.14%|
The 5.1 update on the Nexus 6 reduces 3DMark and Basemark X performance by up to 15%. Even though these tests primarily stress the GPU, the CPU still plays a supporting role. To understand this better, we logged CPU and GPU frequency while running Basemark X.
As expected, the GPU runs at its max frequency of 600MHz during each test segment regardless of OS version. With the initial Android 5.0 build, the Nexus 6 keeps two cores offline and the other two above the 1497MHz threshold most of the time and at least one core at max frequency fairly often. CPU behavior with the 5.1 update looks very different. No single core runs at max frequency for very long, with cores taking turns jumping from 300MHz to 2649MHz and back down again. There’s also several gaps where all four cores are sitting at 300MHz. Looking at the raw data also shows that only one or two CPU cores are above idle at any given time, so having all four cores online does not provide any performance advantage in this particular benchmark.
Things aren’t all bad, however, as we see small performance improvements in the GFXBench Manhattan, T-Rex, and Alpha Blending tests, indicating that some games will see an uptick in performance.