On Wed, Jan 20, 2021 at 08:30:56PM +0800, Anand Jain wrote: > I ran fio tests again, now with dstat in an another window. I don't > notice any such stalls, the read numbers went continuous until fio > finished. Could you please check with the below fio command, also > could you please share your fio command options.
That's the fio config I used: https://gitlab.com/vadorovsky/playground/-/blob/master/fio/btrfs-raid1-seqread.fio The main differences seem to be: - the number of jobs (I used the number of CPU threads) - direct vs buffered I/O > > fio \ > --filename=/btrfs/largefile \ > --directory=/btrfs \ > --filesize=50G \ > --size=50G \ > --bs=64k \ > --ioengine=libaio \ > --rw=read \ > --direct=1 \ > --numjobs=1 \ > --group_reporting \ > --thread \ > --name iops-test-job > > It is system specific? With this command, dstat output looks good: https://paste.opensuse.org/view/simple/93159623 So I think it might be specific to whether we test direct of buffered I/O. Or to the number of jobs (single vs multiple jobs). Since the most of I/O on production environments is usually buffered, I think we should test with direct=0 too. Cheers, Michal
