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1.4.2.5 Configuration Differences in MySQL 5.4 from MySQL 5.1 »
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1.4.2.4. Diagnostic and Monitoring Capabilities

MySQL 5.4 provides improved access to execution and performance information. Diagnostic improvements include Dtrace probes, expanded SHOW ENGINE INNODB STATUS output, and a new status variable.

DTrace Support

MySQL 5.4 includes support for DTrace. The DTrace probes work on Solaris, Mac OS X, and FreeBSD. For information on using DTrace in MySQL, see Section 5.7, “Tracing mysqld Using DTrace”.

Enhanced SHOW ENGINE INNODB STATUS Output

The output from SHOW ENGINE INNODB STATUS includes more information due to changes made for InnoDB Plugin. A description of revisions to statement output follows.

A new BACKGROUND THREAD section has srv_master_thread lines that show work done by the main background thread. 

----------
BACKGROUND THREAD
----------
srv_master_thread loops: 53 1_second, 44 sleeps, 5 10_second, 7 background,
  7 flush
srv_master_thread log flush and writes: 48

The SEMAPHORES section includes a line to show the number of spinlock rounds per OS wait for a mutex. 

----------
SEMAPHORES
----------
...
Spin rounds per wait: 0.00 mutex, 20.00 RW-shared, 0.00 RW-excl

New Status Variable

The Innodb_have_atomic_builtins status variable provides information about availability of atomic instructions; see Section 1.4.2.1, “Scalability Improvements”.