Bug #95599 Best performance when innodb_flush_method = nosync, and a performance regression

• Submitted: 2 Jun 2019 13:05
• Modified: 4 Jun 2019 11:44
• Reporter: haochen he
• Status: Not a Bug
• Category: MySQL Server
• Severity: S5 (Performance)
• Version: 5.7.7
• OS: CentOS
• CPU Architecture: Any
• Tags: performance

[2 Jun 2019 13:05] haochen he

Description:
I run performance test using sysbench and get the following result in 5.7.7, the average latency is around 15 ms:

https://haochenhe-public.s3-ap-northeast-1.amazonaws.com/distribution_3.png

Then I tried the same test on 8.0.12, however, the results are almost same(average latency is around 35 ms) under either of the values('O_DIRECT', 'O_DIRECT_NO_FSYNC', 'fsync', 'littlesync', 'nosync')

It is as expected?

Thank you.

How to repeat:
sysbench parameters are in the picture above.

No other changes are made in my.cnf

[4 Jun 2019 11:44] MySQL Verification Team

Hi,

Thank you for your bug report.

Results are expected and not expected. It depends on your data, your hardware, your OS, settings in hardware, the OS settings, other settings in MySQL and so on ...

Some of these settings might not be supported on your hardware or OS, for example.