68 lines
1.7 KiB
Groff
68 lines
1.7 KiB
Groff
.\" -*- nroff -*-
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.TH ELVTUNE 8 "March 2000" "util-linux" "System Administration"
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.SH NAME
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elvtune \- I/O elevator tuner
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.SH SYNOPSIS
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.B elvtune
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.RB [ \-r
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.IR r_lat ]
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.RB [ \-w
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.IR w_lat ]
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.RB [ \-b
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.IR b_max ]
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.IR device ...
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.br
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.B elvtune \-h
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.br
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.B elvtune \-v
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.SH DESCRIPTION
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.B elvtune
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allows to tune the I/O elevator per blockdevice queue. The
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tuning can be safely done at runtime. Tuning the elevator means
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being able to change disk performance and interactiveness.
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In the output of
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.B elvtune
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the address of the queue tuned will be shown;
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it can be considered as a queue ID.
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Multiple partitions on the same harddisk will
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share the same queue and so tuning one partition will be
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like tuning the whole HD.
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.SH OPTIONS
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.TP
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.BI -r \ r_lat
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Set the maximum latency that the I/O scheduler will provide on
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each read.
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.TP
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.BI -w \ w_lat
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Set the maximum latency that the I/O scheduler will provide on
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each write.
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.TP
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.BI -b \ b_max
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Set the maximum coalescing factor allowed on writes when there are reads
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pending in the queue.
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.TP
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.BI -h
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Display help text and exit.
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.TP
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.BI -v
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Display version version information and exit.
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.SH NOTE
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Actually, the only fields tunable are those relative
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to the IO scheduler. It's not possible to select
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a one-way or two-way elevator yet.
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.PP
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For logical blockdevices like LVM the tuning has to
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be done on the
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.I physical
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devices. Tuning the queue of the LVM logical device
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is useless.
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.SH RETURN VALUE
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0 on success and 1 on failure.
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.SH HISTORY
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Ioctls for tuning elevator behaviour were added in Linux 2.3.99-pre1.
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.SH AUTHORS
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Andrea Arcangeli <andrea@suse.de> SuSE
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.SH AVAILABILITY
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The elvtune command is part of the util-linux package and is available from
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ftp://ftp.kernel.org/pub/linux/utils/util-linux/.
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