Re: linux deadline i/o elevator tuning

On 9-4-2009 16:09 Kevin Grittner wrote:
> I haven't benchmarked it, but when one of our new machines seemed a
> little sluggish, I found this hadn't been set.  Setting this and
> rebooting Linux got us back to our normal level of performance.

Why would you reboot after changing the elevator? For 2.6-kernels, it
can be adjusted on-the-fly for each device separately (echo 'deadline' >
/sys/block/sda/queue/scheduler).

I saw a nice reduction in load and slowness too after adjusting the cfq
to deadline for a machine that was at its maximum I/O-capacity on a
raid-array.
Apart from deadline, 'noop' should also be interesting for RAID and
SSD-owners, as it basically just forwards the I/O-request to the device
and doesn't do much (if any?) scheduling.

Best regards,

Arjen