I'm reading the Red Hat I/O Performance Tuning Guide, because hey, it's all Linux, and I might just learn something.
So far, I've learned that RHEL doesn't have sysfsutils. How very weird.
Unlike the /proc/sys/ file system, the /sys/ file system does not have a utility similar to sysctl that can make such changes persistent thoughout (sic) system reboots.
and
However, as mentioned in Section 4, “Selecting a Scheduler”, any tuning made though echo commands to the /sys/ file system is not persistent throughout system reboots. As such, to make any scheduler selection/request queue settings persistent throughout system reboots, use /etc/rc.d/rc.local.
Of course, for all I know, this information may be out of date with respect to the current release, but Debian's had sysfsutils since November 2003.