SHOW ENGINE INNODB MUTEX displays information about
InnoDB mutexes and rw-locks. It can be a useful tuning aid on
multi-core systems. However, with a big buffer pool, the size of
the output may be overwhelming. There is a mutex and rw-lock in
each 16K buffer pool block. It is highly improbable that an
individual block mutex or rw-lock could become a performance
bottleneck, and there are 65,536 blocks per gigabyte.
Starting with InnoDB Plugin 1.0.4,
SHOW ENGINE INNODB MUTEX will skip
the mutexes and rw-locks of buffer pool blocks. Furthermore, it
will not list any mutexes or rw-locks that have never been waited
SHOW ENGINE INNODB MUTEX
only displays information about such mutexes and rw-locks that
does not belong to the buffer pool blocks and for whom there have
been at least one OS level wait.