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ELVTUNE

NAME
SYNOPSIS
DESCRIPTION
OPTIONS
NOTE
RETURN VALUE
HISTORY
AUTHORS
AVAILABILITY

NAME

elvtune − I/O elevator tuner

SYNOPSIS

elvtune [−r r_lat] [−w w_lat] [−b b_max] device...
elvtune −h
elvtune −v

DESCRIPTION

elvtune allows to tune the I/O elevator per blockdevice queue. 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; it can be considered as a queue ID. Multiple partitions on the same harddisk will share the same queue and so tuning one partition will be like tuning the whole HD.

OPTIONS

-r r_lat

Set the maximum latency that the I/O scheduler will provide on each read.

-w w_lat

Set the maximum latency that the I/O scheduler will provide on each write.

-b b_max

Set the maximum coalescing factor allowed on writes when there are reads pending in the queue.

	-h		Display help text and exit.
	-v		Display version version information and exit.

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

AVAILABILITY

The elvtune command is part of the util-linux package and is available from ftp://ftp.kernel.org/pub/linux/utils/util-linux/.

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