Bug #80870 Optimize TC_LOG_MMAP
Submitted: 28 Mar 2016 18:07
Reporter: George Lorch (OCA) Email Updates:
Status: Open Impact on me:
None 
Category:MySQL Server Severity:S3 (Non-critical)
Version:5.6, 5.7 OS:Any
Assigned to:

[28 Mar 2016 18:07] George Lorch
Description:
It seems TC_LOG_MMAP is not optimized nearly as well as TC_LOG_BIN.

How to repeat:
Enabling (but not necessarily using) a second transactional storage engine (such as TokuDB) and log_bin=OFF, the MySQL server will always use TC_LOG_MMAP.

We see much higher disk usage when TC_LOG_MMAP is in use (even for InnoDB only workloads) and PMP shows a lot of time spent in TC_LOG_MMAP::sync.

For more background info, see https://bugs.launchpad.net/percona-server/+bug/1550352