switching Linux kernel I/O scheduling algorithms
 

Hi,


I'm now using Kernel 2.6.4, and in /drivers/block there are the following I/O scheduling algorithms:

elevetor
as-scheduler (anticipatory scheduler)
noop-scheduler
deadline-scheduler


now obvisouly all these algos are not being used at once, so how can I tell the kernel to use one algo, on somesite I saw the following parameter passed to the kernel:

elevetor=deadline

supposedly turned the deadline-scheduler on,

any clues?

Hi, Yes, you need to pass a parameter to the kernel at boot time - I use Lilo, and have a line :

append = "resume=/dev/hda5 splash=silent acpi=off"

this contains the kernel parameters, so just add a further parameter with the elevator=noop (or whatever). Then, in the case of Lilo, rerun the Lilo program before rebooting. I think (but I'm not sure) that incorrect parameters are ignored, so you'll have to check your boot logs to be sure that it's taken effect.

I'm also no sure what are the appropriate parameters, 'deadline', 'noop' and 'as' I'd guess.

You can also (OK I can with a 2.6.10 kernel - I assume you can with a 2.6.4 kernel) - change the scheduler on the fly.

Read this message.

Iain.