Recommendations When Using gcc

It is recommended to use -O3 -mtune=native to achieve maximum speed during LightGBM training.

Using Intel Ivy Bridge CPU on 1M x 1K Bosch dataset, the performance increases as follow:

Compilation Flag	Performance Index
-O2 -mtune=core2	100.00%
-O2 -mtune=native	100.90%
-O3 -mtune=native	102.78%
-O3 -ffast-math -mtune=native	100.64%

You can find more details on the experimentation below:

• Laurae++/Benchmarks

• Laurae2/gbt_benchmarks

• Laurae’s Benchmark Master Data (Interactive)

The image below compares the runtime for training with different compiler options to a baseline using LightGBM compiled with -O2 --mtune=core2. All three options are faster than that baseline. The best performance was achieved with -O3 --mtune=native.