mirror of
https://github.com/torvalds/linux.git
synced 2024-11-28 15:11:31 +00:00
b31966816d
Remove 'as' for as is no longer supported, and we can not use 'elevator=as' any more. Signed-off-by: Wang Sheng-Hui <shhuiw@gmail.com> Signed-off-by: Randy Dunlap <rdunlap@xenotime.net> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
38 lines
1.4 KiB
Plaintext
38 lines
1.4 KiB
Plaintext
To choose IO schedulers at boot time, use the argument 'elevator=deadline'.
|
|
'noop' and 'cfq' (the default) are also available. IO schedulers are assigned
|
|
globally at boot time only presently.
|
|
|
|
Each io queue has a set of io scheduler tunables associated with it. These
|
|
tunables control how the io scheduler works. You can find these entries
|
|
in:
|
|
|
|
/sys/block/<device>/queue/iosched
|
|
|
|
assuming that you have sysfs mounted on /sys. If you don't have sysfs mounted,
|
|
you can do so by typing:
|
|
|
|
# mount none /sys -t sysfs
|
|
|
|
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 deadline or noop schedulers - which
|
|
can improve that device's throughput).
|
|
|
|
To set a specific scheduler, simply do this:
|
|
|
|
echo SCHEDNAME > /sys/block/DEV/queue/scheduler
|
|
|
|
where SCHEDNAME is the name of a defined IO scheduler, and DEV is the
|
|
device name (hda, hdb, sga, or whatever you happen to have).
|
|
|
|
The list of defined schedulers can be found by simply doing
|
|
a "cat /sys/block/DEV/queue/scheduler" - the list of valid names
|
|
will be displayed, with the currently selected scheduler in brackets:
|
|
|
|
# cat /sys/block/hda/queue/scheduler
|
|
noop deadline [cfq]
|
|
# echo deadline > /sys/block/hda/queue/scheduler
|
|
# cat /sys/block/hda/queue/scheduler
|
|
noop [deadline] cfq
|