Commit b2e792ae authored by Christian Loehle's avatar Christian Loehle Committed by Jens Axboe
Browse files

Documentation: block: ioprio: Update schedulers 



This doc hasn't been touched in a while, in the meantime some
new io schedulers were added (e.g. all of mq), some with ioprio
support.

Also reword the introduction to remove reference to CFQ and the
limitation that io priorities only work on reads, which is no longer
true.

Signed-off-by: default avatarChristian Loehle <christian.loehle@arm.com>
Reviewed-by: default avatarJohannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/a86cfdc8-016f-40f1-8b58-0cb15d2a792c@arm.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent baa7d536

Documentation/block/ioprio.rst

+6 −7
Original line number Diff line number Diff line
@@ -6,17 +6,16 @@ Block io priorities 
Intro

-----



With the introduction of cfq v3 (aka cfq-ts or time sliced cfq), basic io

priorities are supported for reads on files.  This enables users to io nice

processes or process groups, similar to what has been possible with cpu

scheduling for ages.  This document mainly details the current possibilities

with cfq; other io schedulers do not support io priorities thus far.

The io priority feature enables users to io nice processes or process groups,

similar to what has been possible with cpu scheduling for ages. Support for io

priorities is io scheduler dependent and currently supported by bfq and

mq-deadline.



Scheduling classes

------------------



CFQ implements three generic scheduling classes that determine how io is

served for a process.

Three generic scheduling classes are implemented for io priorities that

determine how io is served for a process.



IOPRIO_CLASS_RT: This is the realtime io class. This scheduling class is given

higher priority than any other in the system, processes from this class are