innodb_lru_scan_depth:每个缓冲池刷脏页的能力

innodb_io_capacity:  iops

inoodb_buffer_pool_instances=8 :缓冲池的个数

.关系:       innodb_io_capacity >= innodb_lru_scan_depth * inoodb_buffer_pool_instances

innodb_io_capacity >=innodb_lru_scan_depth*inoodb_buffer_pool_instances。与 checkpoint_缓冲池