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
原文：http://www.cnblogs.com/zengkefu/p/5695909.html