Altera has just released their optimisation guide for OpenCL-on-FPGAs. It does not go into the howto’s of OpenCL, but assumes you have knowledge of the technology. Niether does it provide any information on the basics of Altera’s Stratix V or other FPGA.

It is the first public optimisation document, so it is appreciated to send feedback directly. Not aware what OpenCL can do on an FPGA? Watch the below video.

Subjects

The following subjects and optimisation tricks are discussed:

• FPGA Overview
• Pipelines
• Good Design Practices
• Avoid Pointer Aliasing
• Avoid Expensive Functions
• Avoid Work-Item ID-Dependent Backward Branching
• Aligned Memory Allocation
• Ensure 4-Byte Alignment for All Data Structures
• Maintain Similar Structures for Vector Type Elements
• Optimization of Data Processing Efficiency
• Specify a Maximum Work-Group Size or a Required Work-Group Size
• Loop Unrolling
• Resource Sharing
• Kernel Vectorization
• Multiple Compute Units
• Combination of Compute Unit Replication and Kernel SIMD Vectorization
• Resource-Driven Optimization
• Floating-Point Operations
• Optimization of Memory Access Efficiency
• General Guidelines on Optimizing Memory Accesses
• Optimize Global Memory Accesses
• Perform Kernel Computations Using Constant, Local or Private Memory
• Single Work-Item Execution

Carefully compare these with CPU and GPU optimisation guides to be able to write more generic OpenCL code.

Download

You can download the document here.

If you have any question on OpenCL-on-FPGAs, OpenCL, generic optimisations or Altera FPGAs, feel welcomed to contact us.