优化编译环境Optimizing a build environment (optional)

https://source.android.com/source/initializing.html#optimizing-a-build-environment

Put the following in your .bashrc (or equivalent):

export USE_CCACHE=1

By default the cache will be stored in ~/.ccache. If your home directory is on NFS or some other non-local filesystem, you will want to specify the directory in your .bashrc file as well:

export CCACHE_DIR=<path-to-your-cache-directory>

The suggested cache size is 50-100GB. You will need to run the following command once you have downloaded the source code:

prebuilts/misc/linux-x86/ccache/ccache -M 50G