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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: Christian Loehle <christian.loehle@arm.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/a86cfdc8-016f-40f1-8b58-0cb15d2a792c@arm.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Christian Loehle 2024-01-18 09:29:56 +00:00 committed by Jens Axboe
parent baa7d53607
commit b2e792ae88
1 changed files with 6 additions and 7 deletions
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13
Documentation/block/ioprio.rst
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@ -6,17 +6,16 @@ Block io priorities
Intro Intro
----- -----
With the introduction of cfq v3 (aka cfq-ts or time sliced cfq), basic io The io priority feature enables users to io nice processes or process groups,
priorities are supported for reads on files. This enables users to io nice similar to what has been possible with cpu scheduling for ages. Support for io
processes or process groups, similar to what has been possible with cpu priorities is io scheduler dependent and currently supported by bfq and
scheduling for ages. This document mainly details the current possibilities mq-deadline.
with cfq; other io schedulers do not support io priorities thus far.
Scheduling classes Scheduling classes
------------------ ------------------
CFQ implements three generic scheduling classes that determine how io is Three generic scheduling classes are implemented for io priorities that
served for a process. determine how io is served for a process.
IOPRIO_CLASS_RT: This is the realtime io class. This scheduling class is given 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 higher priority than any other in the system, processes from this class are