Thank you for the information. Yes I'm indeed using libaio as the ioengine on a linux server. For command 2, what is the logic? If I'm specifying numjobs=2 & iodepth=4 will each job get 2 IO depth, or does it mean each job will be running with IO depth 4? This is a bit confusing for me. For command 3, will each disk have : 1. 2 jobs per disk with 4 IO depth for each job? 2. 2 jobs per disk with 2 IO depth for each job? 2. One job per disk with 2 IO depth for each job? 3. One job per disk with 4 IO depth? -- Cheers Manu K S On Sat, May 18, 2019 at 12:43 PM Sitsofe Wheeler <sitsofe@xxxxxxxxx> wrote: > > Hi, > > On Fri, 17 May 2019 at 16:20, Manu K.S. <cse.manuks@xxxxxxxxx> wrote: > > > > Hi, what will be the iodepth for each job with below 3 commands? > > > > COMMAND 1 > > ----------------- > > fio --name=fiotest --filename=/dev/sdb --rw=read --numjobs=1 > > --iodepth=4 --size=1G --bs=4k --runtime=120 --time_based > > > > COMMAND 2 > > ------------------- > > fio --name=fiotest --filename=/dev/sdb --rw=read --numjobs=2 > > --iodepth=4 --size=1G --bs=4k --runtime=120 --time_based > > > > COMMAND 3 > > ------------------- > > fio --name=fiotest --filename=/dev/sdb:/dev/sdc --rw=read --numjobs=2 > > --iodepth=4 --size=1G --bs=4k --runtime=120 --time_based > > Hard to say without more context but assuming you're on Linux: > > COMMAND 1 > You're going to get a depth of 1 because the default ioengine chosen > when you don't specify one on Linux is synchronous (see the iodepth > description in the fio help for warnings about depth and synchronous > ioengines - https://fio.readthedocs.io/en/latest/fio_doc.html#cmdoption-arg-iodepth > ). Maybe you wanted to use libaio with direct=1 (see the libaio > section in https://fio.readthedocs.io/en/latest/fio_doc.html#cmdoption-arg-ioengine > for more details)? > > COMMAND 2 > I'd guess you will get an overall depth of 2 (1 per job). > > COMMAND 3 > I'd guess you will get an overall depth of 2 (1 per job). Multiple > files in filename won't impact the depth only which file each I/O goes > to (which is roundrobin by default - > https://fio.readthedocs.io/en/latest/fio_doc.html#cmdoption-arg-file-service-type > ). > > NB: fio will try and report the depths it is achieving see the "IO > depths" output in the example on > https://fio.readthedocs.io/en/latest/fio_doc.html#interpreting-the-output > . What your disk actually sees can be different though depending on > what the kernel chooses to do with the submitted I/O. > > -- > Sitsofe | http://sucs.org/~sits/
