About Altera OpenCL Compilation

Hi,

I do not have any data on Windows vs. Linux Quartus compilation times. This could already be mentioned in other Altera forums.

Quartus may behave slightly differently (place/route) between platforms. This explains why you are sometimes seeing different aocx performances. I think there is no clear winner platform; the difference is more like running the same algorithm with different seeds. You can again refer to other forums for possible more detailed answers.

When it comes to the aoc compilation, my observation is that Linux could be faster just because gcc does a better job. Otherwise, aoc compiler should behave exactly the same way on Linux and on Windows, i.e. you will obtain the same Verilog output for the same input file.

Compilation flow is mostly the same whether the kernel is a task or an ndrange. The most significant difference stems from loop-carried memory dependences. If your task kernel has significant number of memory operations that have memory dependences carried by loops, computing these dependences and generating the appropriate hardware may take some time. Eliminating these dependences will reduce the compile-time as well as may increase performance.

The latency of local memory accesses mainly depends on the complexity of the local memory system that is generated. If a load/store instruction is the only instruction that is connected to a local memory port, its latency will be minimal. However, if multiple local memory accesses are going to the same port then the latency will be increased to account for this "competition" (i.e. interconnect). You can refer to the "Optimizing Local Memory Accesses" Section in the "Best Practices Guide".