This is another performance improvement that comes for free, with no user action or configuration needed. The details here are intended for performance experts who delve into the InnoDB source code, or interpret reports with keywords such as “mutex” and “log_sys”.
The mutex known as the log sys
mutex has historically done double duty, controlling access to
internal data structures related to log records and the
LSN, as well as pages in the
buffer pool that are
changed when a
committed. Starting in InnoDB 1.1 with MySQL 5.5, these two kinds
of operations are protected by separate mutexes, with a new
log_buf mutex controlling writes to buffer pool
pages due to mini-transactions.
For performance considerations for InnoDB locking operations, see Optimizing Locking Operations.