Zach,

On Thu, Aug 11, 2011 at 12:56 AM, Zach Pfeffer <zach.pfeffer@linaro.org> wrote:

The demo consisted of two identical PandaBoards with identical SD
cards running the 3D benchmark of 0xbench using software 3D to amplify
compiler and kernel improvements. 0xbench is a benchmarking program we
ship with our Android images from 0xlab. Each build ran the same
Android userspace, 2.3.4, but one was using the 2.6.36 Linux kernel
and GCC 4.4 from the stock AOSP distribution and one was using an
upgraded Linaro 3.0 Linux kernel with Linaro GCC 4.5. We ran the board
in 640x480 mode so that we wouldn't be memory bound.

have you checked all clock configuration and ensure they are the same? .36 seems quite old (in the pandaboard lifetime) and i would suspect the CPU and memory clocks could be wrong compared to the linaro 3.0 (which I tried recently and which seems to have the right config). there are all bunch of kernel settings that can largely impact your demo like cache settings for example...

since DVFS is not enabled in both kernel I believe, the clock setting might very well come from the bootloaders. which xloader and uboot are you using in both cases?

have you tried to run the same demo with the exact same bootloaders and kernel? just a different user space built with 2 different compilers? I don't expect performances improvements to come from the kernel anyways (at least for such benchmark) that way you are sure you are really looking at GCC improvements. similarly you can run the same user space with both kernels.