Tejun Heo [off-list ref] 于2020年3月27日周五 上午12:15写道：

On Thu, Mar 26, 2020 at 11:08:45PM +0800, Weiping Zhang wrote:

quoted

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.

OK, I'll try it.

I really appreciate that if you help review blk-iotrack.c, or just
drop io.iotrakc.stat
and append these  statistics to the io.stat? I think these metrics is usefull,
and it just extend io.stat output.

Thanks a ton