Parallella Community

Think I got at least one problem figured out. If copy memcpy from into my own code, it results in roughly the same benchmark values as when I adapt my own code to copy 8 instead of 64 bits. So I guess the low memcpy performance comes from the standard C library being in the external dram instead of SRAM.

However I am still wondering why O3 will, instead if optimizing my code for speed, makes my code so much slower.

Do not execute any code from external memory if you want reasonable performance. Use internal.ldf as linker script.

You can use my shmemx_memcy routine if you need best performance. Nothing else beats it while also handling address misalignment.
https://github.com/USArmyResearchLab/op ... x_memcpy.c

Thanks! I am using the Parallella board for my bachelor thesis so maybe it is nice to compare the results I finally get with your implementation.

Totally agree with sebraa.
Performance is my only goal.
Use internal.ldf or nothing.
Avoid using the libraries as much as possible.
gcc bit handling emulation for example is really poor, I had to replace them with my own (popcount, clz).