Altera_Forum
Honored Contributor
Honored ContributorO3 Optimization features
Hi ,
I just wanted to know the impact of O3 optimization flag with the aoc compiler... The logic utilization seems to increase with O3. What are all the features of O3 ?Forum Discussion
3 Replies
Altera_ForumO3 would automatically increase the number of compute units or SIMD lanes.
- Altera_Forum
-O3 sweeps various parameters to attempt to increase the work-items/s metric. It explores these parameters until there are diminising returns (like too large of a hardware footprint). When I use the -O3 flag I often take the final parameter set explored by the -O3 flag and use the same parameters for subsequent compiles into of repeatively using the -O3 flag.
- Altera_Forum
I just want to add that, as explained in the altera optimization guide (http://www.altera.com/literature/hb/opencl-sdk/aocl_optimization_guide.pdf), the resource-driven optimizer will use maximum 85% of the logic. You can however force it to another value if you want.
--- Quote Start --- If you do not specify the maximum logic utilization, the resource-driven optimizer uses a maximum logic utilization of 85%. To enable the resource-driven optimizer with a maximum FPGA hardware utilization of 85%, omit the --util flag, as shown below: aoc -O3 <your_kernel_filename>.cl To specify a maximum FPGA hardware utilization percentage other than 85% (for example, 50%), invoke the following command: aoc -O3 --util 50 <your_kernel_filename>.cl --- Quote End ---
