Created: 2010-09-19
Last modified: 2010-09-19

MySQL Performance: 5.5 notes

by Dimitri

OSC Team, 2010
Oracle / Sun Microsystems Inc.

Ces informations sont données à titre indicatif et n'engagent pas Sun Microsystems.

Table of contents

Benchmark Information
Customer Name(s): MySQL Perf Team

NDA: ..

Contact Information: dimitri (dot) kravtchuk (at) oracle (dot) com

Dates: Sep.2010

Keywords: MySQL 5.5, InnoDB, flushing, concurrency, In Memory, IO bound

Hardware Configuration
Server(s): 32 cores Intel box

Storage: Internal SSD disks

Software Configuration


Overview: Since 5.5.6 version the MySQL 5.5 is announced as RC, so no radical new changes will be allowed in the code anymore, but there is still a room for some performance improvements even with a minimal changes.. Here are some notes about potential improvement in MySQL 5.5 performance.

Goal(s): improve performance, of course :-)


Last month I've got some time to focus on the Buffer Pool pages management I've observed many months before with older MySQL/InnoDB versions, and now was curious if I'll reproduce the same issue with MySQL 5.5.4 too...

Few words about the tested workload:

What I observed before is that even if every UPDATE is changing data in place, there is a continuous decrease of the free space in the buffer pool! - and over a time all the space is used by something else rather useful data, etc.. - means probably "useful data" are leaving the cache and filled by old page images, etc.

So far - yes, I've reproduced the same problem again and with MySQL 5.5.4 - and you may read all details about in the Buffer Pool and Purge report. But to make it short: it's once again about InnoDB purge - if purge is unable to follow your workload activity you may have many problems, and this problem is one of them :-))

I did not really think to publish this report before I have a detailed in depth explanation about everything is going on.. - But several things happened during this time:

Let me speak about the Linux kernel :-))

Detailed STATs during workloads
Here you may find all detailed system and InnoDB stats observed during tested workloads.

Abbreviation used in titles :

Workload STATs :
Detailed STATs during workloads