innodb_io_capacity、innodb_io_capacity_max 的影响

os: centos 7.4
db: mysql 8.0.19

innodb_io_capacity、innodb_io_capacity_max 控制的是 innodb 刷脏页的能力。

过小会导致 mysql 刷脏页能力不足，影响性能。
过大会让 mysql 认为 io 能力很强，会造成 io 尖峰。

版本

# cat /etc/centos-release
CentOS Linux release 7.4.1708 (Core) 
# 
# 
# yum list installed |grep -i mysql
mysql-community-client.x86_64              8.0.19-1.el7                @mysql80-community
mysql-community-common.x86_64              8.0.19-1.el7                @mysql80-community
mysql-community-devel.x86_64               8.0.19-1.el7                @mysql80-community
mysql-community-libs.x86_64                8.0.19-1.el7                @mysql80-community
mysql-community-libs-compat.x86_64         8.0.19-1.el7                @mysql80-community
mysql-community-server.x86_64              8.0.19-1.el7                @mysql80-community
mysql-community-test.x86_64                8.0.19-1.el7                @mysql80-community
mysql80-community-release.noarch           el7-3                       installed

# mysql

mysql> select version();
+-----------+
| version() |
+-----------+
| 8.0.19    |
+-----------+
1 row in set (0.00 sec)

创建基础表

mysql> use test;

mysql> create table tmp_t0 (
	c0 bigint not null,
	c1 varchar(100) not null,
	c2 varchar(100) not null,
	primary key (c0)
)
engine=innodb
default charset=utf8mb4
collate=utf8mb4_bin;

mysql> delimiter $$
create procedure insert_into_tmp_t0(
   in start_num int(10),
   in max_num   int(10)
)
begin  
   declare i int default 0;   
   set autocommit = 0;    
   repeat  
      set i = i + 1;  
      insert into tmp_t0 (c0,c1,c2) 
	       values (start_num+i,md5(start_num+i),md5(start_num+i));  
      until i = max_num
   end repeat;  
   commit;  
 end$$
delimiter ;

mysql> call insert_into_tmp_t0(0,1000000);

mysql> create table tmp_t100 as select * from tmp_t0 where 1=2;

mysql> alter table tmp_t100 add primary key (c0);


mysql> create table tmp_t2000 as select * from tmp_t0 where 1=2;

mysql> alter table tmp_t2000 add primary key (c0);

innodb_io_capacity 默认值

# mysql

mysql> show global variables like '%io_cap%';
+------------------------+-------+
| Variable_name          | Value |
+------------------------+-------+
| innodb_io_capacity     | 200   |
| innodb_io_capacity_max | 2000  |
+------------------------+-------+
2 rows in set (0.00 sec)

innodb_io_capacity=100

mysql> set global innodb_io_capacity=100;
set global innodb_io_capacity_max=200;

mysql> show global variables like '%io_cap%';
+------------------------+-------+
| Variable_name          | Value |
+------------------------+-------+
| innodb_io_capacity     | 100   |
| innodb_io_capacity_max | 200   |
+------------------------+-------+
2 rows in set (0.00 sec)

mysql> truncate table tmp_t100;

mysql> insert into tmp_t100 select * from tmp_t0;
Query OK, 1000000 rows affected (18.76 sec)
Records: 1000000  Duplicates: 0  Warnings: 0

innodb_io_capacity=2000

mysql> set global innodb_io_capacity=2000;
set global innodb_io_capacity_max=4000;

mysql> show global variables like '%io_cap%';
+------------------------+-------+
| Variable_name          | Value |
+------------------------+-------+
| innodb_io_capacity     | 2000  |
| innodb_io_capacity_max | 4000  |
+------------------------+-------+
2 rows in set (0.00 sec)

mysql> truncate table tmp_t2000;

mysql> insert into tmp_t2000 select * from tmp_t0;

Query OK, 1000000 rows affected (19.48 sec)
Records: 1000000  Duplicates: 0  Warnings: 0

参考:
https://dev.mysql.com/doc/refman/8.0/en/innodb-configuring-io-capacity.html
https://www.cnblogs.com/glon/p/6484912.html