MySQL server can't be run as root, you will need to create a new user to run MySQL server.
Which directories in the MySQL server installation path need to be specified when building Sysbench?
In order to run Sysbench against MySQL server, both the include and the lib directories under the MySQL server installation need to be specified when building Sysbench.
To enable PGO, you will need to build, profile, and then rebuild with profile data.
Both GCC and Clang support PGO.