As of the Linux 2.6.10 kernel, it is now possible to change the
IO scheduler for a given block device on the fly (thus making it possible,
for instance, to set the CFQ scheduler for the system default, but
-set a specific device to use the anticipatory or noop schedulers - which
+set a specific device to use the deadline or noop schedulers - which
can improve that device's throughput).
To set a specific scheduler, simply do this:
will be displayed, with the currently selected scheduler in brackets:
# cat /sys/block/hda/queue/scheduler
-noop anticipatory deadline [cfq]
-# echo anticipatory > /sys/block/hda/queue/scheduler
+noop deadline [cfq]
+# echo deadline > /sys/block/hda/queue/scheduler
# cat /sys/block/hda/queue/scheduler
-noop [anticipatory] deadline cfq
+noop [deadline] cfq
arch/x86/kernel/cpu/cpufreq/elanfreq.c.
elevator= [IOSCHED]
- Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
+ Format: {"cfq" | "deadline" | "noop"}
See Documentation/block/as-iosched.txt and
Documentation/block/deadline-iosched.txt for details.
To quote Linux Weekly News:
There are a number of red-black trees in use in the kernel.
- The anticipatory, deadline, and CFQ I/O schedulers all employ
- rbtrees to track requests; the packet CD/DVD driver does the same.
+ The deadline and CFQ I/O schedulers employ rbtrees to
+ track requests; the packet CD/DVD driver does the same.
The high-resolution timer code uses an rbtree to organize outstanding
timer requests. The ext3 filesystem tracks directory entries in a
red-black tree. Virtual memory areas (VMAs) are tracked with red-black