Re: [PATCH] sched: Add SCHED_BGND (background) scheduling policy

[Con Kolivas <kernel@kolivas.org>]

On Wednesday 05 July 2006 09:35, Peter Williams wrote:
> Problem:
>
> There is a genuine need for the ability to put tasks in the background
> (a la the SCHED_IDLEPRIO policy in Con Kolivas's -sc kernels) as is
> evidenced by comments in LKML re a desire for SCHED_BATCH tasks
> to run completely in the background.
>
> Solution:
>
> Of course, one option would have been to just modify SCHED_BATCH so
> that tasks with that policy run completely in the background but there is a
> genuine need for a non background batch policy so the solution adopted
> is to implementa a new policy SCHED_BGND.
>
> SCHED_BATCH means that it's a normal process and should get a fair
> share of the CPU in accordance with its "nice" setting but it is NOT an
> interactive task and should NOT receive any of the special treatment
> that a task that is adjudged to be interactive receives.  In particular,
> it should always be moved to the expired array at the end of its time
> slice as to do otherwise might result in CPU starvation for other tasks.
>
> SCHED_BGND means it's totally unimportant and should only be given the
> CPU if no one else wants it OR if not giving it the CPU could lead to
> priority inversion or starvation of other tasks due to this tasks holding
> system resources.

Could we just call it SCHED_IDLEPRIO since it's the same thing and there are 
tools out there that already use this name?

-- 
-ck
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