Intro
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-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
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-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