ARM JPEG Benchmarks part 2
I thought it would be useful to re-run the tests with the C version of my JPEG code. From the results it appears that memory bandwidth is the real limiting factor to the speed and the pixel colorspace conversion gets the most benefit from my optimized ARM assembly language. Also it appears that the OMAP gains more from optimized ASM than the XScale does. Here are the numbers:
C-Code:
PPC: thumbnail: 10.7 milliseconds, DC only: 968 milliseconds, full res: 3734 milliseconds.
SP: thumbnail: 25.1 milliseconds
Mixed C and ASM
PPC: thumbnail: 8.8 milliseconds, DC only: 830 milliseconds, full res: 2700 milliseconds.
SP: thumbnail: 15.1 milliseconds
The load times for the “DC only” and “full res” tests include the time taken to read 4.3MB of data from RAM through the WinCE file system.
These results make sense in that the real benefit of optimization comes from fixing the algorithms and reducing memory usage. The optimized ARM assembly code is certainly helpful in speeding things up, but won’t offer an order of magnitude improvement over what the compiler generates.
