I wanted to add to this discussion that both irix and hpux support
this kind of tasks, even better than we do with SCHED_IDLE, by
extending the realtime priority to a wieder range:
pri > 0 run always unless preempted by another rt task
pri < 0 run never unless no sched_other task and no higher priority
rt task runs
I _lot_ of machiens are used as desktops at the day and for computations at
night. It does not make sense to detract 10% of the speed at the day when
everybody wants low latency. nice +19 processes get quite a big part of the
cpu time.
As a practical example, when I do a long-running compilation (xfree or
glibc), I start it as an idle task. This gives me (almost) full interaktive
performance for the edit/compile/debug cycle, while giving all idle time to
the background job.
I admit that the idle scheduling is not perfect, but standard linux has
nothing comparable. If a nice +19 process wouldn't eat much cpu time I
wouldn't say anything, but they take performance down noticably. So why does
everybody bang on that useful patch, when linux doesn't give anything
comparable in the standard distribution?
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---==---(_)__ __ ____ __ Marc Lehmann +--
--==---/ / _ \/ // /\ \/ / pcg@goof.com |e|
-=====/_/_//_/\_,_/ /_/\_\ --+
The choice of a GNU generation |
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