elvtune

 

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 ELVTUNE(8)                                             ELVTUNE(8)
 
 
 
NAME
        elvtune - I/O elevator tuner
 
SYNOPSIS
        elvtune  [  -r  r_lat  ]  [  -w  w_lat  ]  [  -b  b_max  ]
        /dev/blkdev1 [ /dev/blkdev2 ...  ]
 
        elvtune -h
 
        elvtune -v
 
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  per­
        formance 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 tun­
        ing one partition will be like tuning the whole HD.
 
OPTIONS
        -r r_lat
               set  the  max  latency  that the I/O scheduler will
               provide on each read.
 
        -w w_lat
               set the max latency that  the  I/O  scheduler  will
               provide on each write.
 
        -b b_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
 
 
 
 Version 1.0               14 March 2000                ELVTUNE(8)

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