On Thu, Mar 26, 2020 at 11:08:45PM +0800, Weiping Zhang wrote: > But iocost_test1 cannot get 8/(8+1) iops, and the total disk iops > is 737559 < 79388, even I change rrandiops=637000. iocost needs QoS targets set especially for deep queue devcies. W/o QoS targets, it only throttles when QD is saturated, which might not happen at all depending on fio job params. Can you try with sth like the following in io.cost.qos? 259:0 enable=1 ctrl=user rpct=95.00 rlat=5000 wpct=50.00 wlat=10000 In case you see significant bw loss, step up the r/wlat params. Thanks. -- tejun