On 2019/09/19 12:59, Liu, Sunny wrote: > Thank very much for your quickly advice. > > The problem drive is sata HDD 7200rpm in raid 5. Sorry, I read "SDD" where you had written "HDD" :) Is this a hardware RAID ? Or is this using dm/md raid ? > If using Fio libaio iodepth=128 numjob=2, the bad performance will be as below > in red. But there is no problem with numjob=1. In our solution, *multiple > threads* should be used. Your data does not have the numjobs=1 case for kernel 5.2.9. You should run that for comparison with the numjobs=2 case on the same kernel. > From the testing result, BFQ low-latency had good performance, but it still has > problem in 1m seq write. > > The data is come from centos 7.6 (kernel 3.10.0-975) and kernel 5.2.9 with BFQ > and bcache enabled. No bcache configure. > > Is there any parameter can solve the 1m and upper seq write problem with > multiple threads? Not sure what the problem is here. You could look at a blktrace of each case to see if there is any major difference in the command patterns sent to the disks of your array, in particular command size. -- Damien Le Moal Western Digital Research
