Name
elvtune — I/O elevator tuner
Synopsis
elvtune [ −r r_lat ] [ −w w_lat ] [ −b b_max ] /dev/blkdev1 [
/dev/blkdev2... ]
DESCRIPTION
elvtune
allows to tune the I/O elevator per blockdevice queue basis.
The tuning can be safely done at runtime. Tuning the elevator
means being able to change disk performance and
interactiveness. In the output of elvtune the address of the
queue tuned will be shown and it can be considered as a queue
ID. For example multiple partitions in the same harddisk will
share the same queue and so tuning one partition will be like
tuning the whole HD.
OPTIONS
−rr_lat-
set the max latency that the I/O scheduler will
provide on each read.
−ww_lat-
set the max latency that the I/O scheduler will
provide on each write.
−bb_max-
max coalescing factor allowed on writes when there
are reads pending in the queue.
−h-
help.
−v-
version.
NOTE
Actually the only fields tunable are those relative to the
IO scheduler. It's not possible to select a one-way or
two-way elevator yet.
For logical blockdevices like LVM the tuning has to be
done on the physical devices. Tuning the
queue of the LVM logical device is useless.
RETURN VALUE
0 on success and 1 on failure.
HISTORY
Ioctls for tuning elevator behaviour were added in Linux
2.3.99-pre1.
AUTHORS
Andrea Arcangeli <andrea@suse.de> SuSE
