On Linux, the driver's AIO implementation is a compatibility shim that just barely passes the POSIX standard. InnoDB performance suffers when using its default AIO codepath. Set innodb_use_native_aio=0 and innodb_use_atomic_writes=0 in my.cnf to disable AIO. Both of these settings must be disabled to disable AIO.
==== MyISAM ====
Put MyISAM databases on a dataset with recordsize=8K.
=== PostgreSQL ===