- Comments for or against the SCHED_IA class in the generic
Linux kernel source tree.
- General comments::::
With Ingo Molnar's 2.6.22 latest inclusions into the Linux
source base, he has opened an opportunity to add additional
task classes.
This informal 1-pager is to try to identify whether their
is support for the interactive (ia) task class. Posix explicitly
states only three classes. However it states that
implementations may define additional schedulars/classes.
This 1-pager is to address the support for an additional
schedular class SCHED_IA.
Currently interactive tasks are derived from
SCHED_NORMAL based on sleep factors and generate bonuses/credits
to alter their scheduling behaviour. However, this developer
believes that other tasks with different behaviours exist that
COULD also be classified as a ia task.
This developers preconcieved belief is that the ia class could
generally be supported with a minimal amount of effort, be a
benefit to the Linux kernel, and to generally support the
following rules:
* allow root / SUSER (Super USER) to determine that a task
should be classified as a ia (interactive) task without
eviction based on scheduling behaviours,
* allow SCHED_IA priorities be placed between the Real-time
schedulars and SCHED_NORMAL/OTHER,
* derive the interactive behaviour based on its nice value
and/or its initial combined priority,
* TBD : identify whether the priority should be fixed or
have limited variability within the ia interactive class,
* user level command support to identify that a task is a
interactive (ia) task,
* etc (fork behaviours),
Note: this 1-pager is not suggesting the removal or adjustment
of interactive support within the SCHED_NORMAL/OTHER
Linux, currently supported CFS environment.
- Comments for or against the SCHED_IA class in the generic
Linux kernel source tree.
- General comments::::
Mitchell Erblich
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