Running with GPU runtime on android needs opencl library, one can set `MGB_MACE_OPENCL_PATH` by using environment variable
`MGB_MACE_OPENCL_CACHE_PATH` is the directory path where OpenCL binary cache writes to (the cache file name is always `mace_cl_compiled_program.bin`), if the cache file does not exist then it will be created.
We mainly use NCHW data format, if you have NHWC model, use environment `MGB_MACE_LOADER_FORMAT=NHWC`
For CPU runtime, default running thread is 1, could be specified with `MGB_MACE_NR_THREADS=n`
if you want to run with HEXAGON runtime, more efforts should be made, please check [here](https://mace.readthedocs.io/en/latest/faq.html#why-is-mace-not-working-on-dsp).
### Tuning on specific OpenCL device
MACE supports tuning on specific SoC to optimize the performace on GPU, see [doc](https://mace.readthedocs.io/en/latest/user_guide/advanced_usage.html#tuning-for-specific-soc-s-gpu).
To enable this feature, use `MGB_MACE_TUNING_PARAM_PATH` env to give the path to the tuning param file.
To generate the tunig param file, give `MACE_TUNING=1` env and set the `MACE_RUN_PARAMETER_PATH` to the file name you want.