Kernel settings question?

I’m trying to change my Global I/O Scheduler in Yast2 > Kernel Settings to Deadline. Everytime I change it to deadline it goes back to Not Configured. I was reading there is a bug on this. My question is is there a way to change this manually via a config file. Any help is appreciated.

Thanks,
Dwight

Just change the boot options in yast. For grub2: Go to Boot Loader -> Boot Loader Options -> Optional Kernel Command Line Parameter. Append elevator=deadline to the end. This is much easier on grub2 as you only have to do it once. For grub1 I think you have to edit the individual kernels with this option. And again every time you get a new kernel.

Edit you can also just run:

echo deadline > /sys/block/device/queue/scheduler

And this to confirm it works:

cat /sys/block/device/queue/scheduler

Obviously replace device with “sda” or similar. The boot option way works for all devices. The command way only works for the single device specified.

I found an interesting write up on these options here as to what they do: redhat.com | Choosing an I/O Scheduler for Red Hat Enterprise Linux 4 and the 2.6 Kernel

  • Completely Fair Queuing—elevator=cfq (default)
  • Deadline—elevator=deadline
  • NOOP—elevator=noop
  • Anticipatory—elevator=as

I am not sure I would make a change from elevator=cfq, but it looks like you can if you want to.

Thank You,

Neat. I always wondered what you did if you had an SSD and a conventional hard disk, and wanted a different scheduler for each.

Please note it will revert on every boot. So you will need to do add commands to a boot script to make the choices permanent. It is a lot of fun playing with i/o schedulers. I use deadline myself. It seems even with cfq having priorities I still get stutters in audio playback, so I might as well use something a bit simpler. If I could ever get a kernel to compile correctly I would try bfq.

Further to the info nightwishfan has supplied, see my note here: http://forums.opensuse.org/english/get-technical-help-here/hardware/473114-how-do-i-implement-elevator-noop.html#post2446935