On Wed, 2008-12-10 at 17:02 +0100, Peter Kjellstrom wrote: > On Wednesday 10 December 2008, John wrote: > > On Tue, 2008-12-09 at 12:07 -0500, Ross Walker wrote: > > > On Dec 9, 2008, at 10:59 AM, Matt <lm7812 at gmail.com> wrote: > > > >>>> Setting scheduler is global in C4 it can be set as a kernel option > > > >>>> with a scheduler=deadline in grub. > > > >>> > > > >>> Is that an alias for "elevator=deadline" (which I know works)? > > > >> > > > >> No that was me forgetting the option name. > > > >> > > > >> Thanks Peter, it's elevator= not scheduler= > > > > > > > > Does this mean I need to add "elevator=deadline" to grub.conf? Is > > > > there a way to make the change without rebooting? > > > > > > I'm afraid not, so possibly a late night or weekend event with the > > > option for a mid day reboot to recover if things turn out badly. > > > > > > Virtualize things and you can minimize downtime with snapshots. > > > > [root at blah ~]# cat /sys/block/hda/queue/scheduler > > noop anticipatory deadline [cfq] > > The Schedular is CFQ and can be changed on the fly to whatever Block > > Device you want it. > ... > > [root at blah ~]# echo 'deadline' > /sys/block/hda/queue/scheduler > > [root at blah ~]# cat /sys/block/hda/queue/scheduler > > noop anticipatory [deadline] cfq -- Changed to Deadline. > > ...this is correct on CentOS-5. On CentOS-4 you need to do it via grub and a > reboot. Yes follow up to previous mail. That would be correct for those two. My opinions do not change however, I just saw the mail where it did not work because he has V4.x and needs to use grub.conf.