Accessing the performance counters isn’t difficult, but you have to enable them from kernel-mode. By default the counters are disabled. In a nutshell you have to execute the following two lines inside the kernel. Either as a loadable module or just adding the two lines somewhere in the board-init will do: /* enable user-mode access … Read more
The NEON pipeline on Cortex-A8 is in-order executing, and has limited hit-under-miss (no renaming), so you’re limited by memory latency (as you’re using more than L1/L2 cache size). Your code has immediate dependencies on the values loaded from memory, so it’ll stall constantly waiting for memory. This would explain why the NEON code is slightly … Read more
There are quite some difference between the two. Neon is a SIMD (Single Instruction Multiple Data) accelerator processor as part of the ARM core. It means that during the execution of one instruction the same operation will occur on up to 16 data sets in parallel. Since there is parallelism inside the Neon, you can … Read more