Selecting a scheduling policy for MySQL

On Gun/linux, queue scheduling determines the order in which requests to block devices are actually sent to the underlying settings. By default, the CFG (fully fair queuing) policy, free use of notebooks and desktops using the scheduling policy is not a problem, and helps to prevent IO starvation, but for the server is problematic, under the MySQL workload type, CFQ will lead to poor response time, Because some unnecessary requests are deferred in the queue (how to understand them).

A command that can be used to see what the system supports and what scheduling policies are currently in use

cat/sys/block/disk drive letter (e.g. SDA)/queue/scheduler

noop deadline [CFQ] ([] is the scheduling policy in use), two options outside of CFQ are suitable for server-level hardware, and in most cases they work equally well, NoOp scheduling is suitable for those devices that implement the scheduling algorithm behind them (what settings can implement their own scheduling algorithms), such as hard - piece RAID controllers and Sans. Deadline works well for both RAID controllers and directly used disks, and our benchmark shows that the difference between the two is very small, and it is important not to use CFQ, which can lead to serious performance problems.

But this advice also needs to be preserved, because the disk scheduling strategy actually has a lot of different locations in the kernel.