/etc/init.d/ioscheduler: Kernel IO scheduler selector script

ioscheduler (text/plain), 1.60 KB, created by Emmanuel Rosa on 2005-06-01 15:00:55 UTC

#!/sbin/runscript

# Scheduler Descriptions. Taken from the kernel configuration documentation:

# The anticipatory I/O scheduler is the default disk scheduler. It is
# generally a good choice for most environments, but is quite large and
# complex when compared to the deadline I/O scheduler, it can also be
# slower in some cases especially some database loads.

# The deadline I/O scheduler is simple and compact, and is often as
# good as the anticipatory I/O scheduler, and in some database
# workloads, better. In the case of a single process performing I/O to
# a disk at any one time, its behaviour is almost identical to the
# anticipatory I/O scheduler and so is a good choice.

# The CFQ I/O scheduler tries to distribute bandwidth equally
# among all processes in the system. It should provide a fair
# working environment, suitable for desktop systems.

depend() {
	need localmount
}

start() {
	ebegin "Configuring kernel IO schedulers"

	if [ ! -n "${def_io_sched}" ]
	then
		ewarn "You have not selected a default IO scheduler in the config file /etc/conf.d/ioscheduler. Using the anticipatory IO scheduler as default."
		def_io_sched=anticipatory
	fi

	if [ -e /sys ]
	then

		for blockdev in `/usr/bin/ls /sys/block`
		do
			if [ -e /sys/block/${blockdev}/queue/scheduler ]
			then
				eval scheduler=\$io_${blockdev}
				if [ ! -n "${scheduler}" ]
				then
					scheduler=${def_io_sched}
				fi
				einfo "Setting ${blockdev} IO scheduler to ${scheduler}."
				echo ${scheduler} >/sys/block/${blockdev}/queue/scheduler
			fi
		done

	else
		eend $? "sysfs filesystem not available. Unable to configure IO schedulers."
	fi
}