Iosched_switch error

Iosched_switch error

[Matthew Eaton]

Hi Jens,

I have run into this error when using ioscheduler=noop in my job
files. I only run into the error when specifying unsupported devices
such as nvme or md raid device. Should this be a fatal error? I ask
because sometimes I want to run the same job on various devices.

sudo fname=/dev/nvme0n1 ./fio seqread.ini
seq-read: (g=0): rw=read, bs=128K-128K/128K-128K/128K-128K,
ioengine=libaio, iodepth=32
fio-2.12-3-g8a09
Starting 1 process
fio: io scheduler noop not found
fio: pid=5541, err=22/file:backend.c:1306, func=iosched_switch,
error=Invalid argument


Run status group 0 (all jobs):

Disk stats (read/write):
  nvme0n1: ios=0/0, merge=0/0, ticks=0/0, in_queue=0, util=0.00%

Re: Iosched_switch error

[Jens Axboe]

On 06/30/2016 06:05 PM, Matthew Eaton wrote:
> Hi Jens,
>
> I have run into this error when using ioscheduler=noop in my job
> files. I only run into the error when specifying unsupported devices
> such as nvme or md raid device. Should this be a fatal error? I ask
> because sometimes I want to run the same job on various devices.
>
> sudo fname=/dev/nvme0n1 ./fio seqread.ini
> seq-read: (g=0): rw=read, bs=128K-128K/128K-128K/128K-128K,
> ioengine=libaio, iodepth=32
> fio-2.12-3-g8a09
> Starting 1 process
> fio: io scheduler noop not found
> fio: pid=5541, err=22/file:backend.c:1306, func=iosched_switch,
> error=Invalid argument

IO scheduler switching can only work, if the device is using an IO 
scheduler. md/raid devices are not, and nvme is driven by blk-mq, which 
doesn't have an IO scheduler either. That's why these devices fail for you.

-- 
Jens Axboe