SCHED_DEADLINE returns [LWN.net]

SCHED_DEADLINE returns

Posted Apr 12, 2012 7:24 UTC (Thu) by flok (guest, #17768)
Parent article: SCHED_DEADLINE returns

I wonder if it would be helpfull if an application could somehow tell the scheduler of the amount of time it'll need to do its job. Then the scheduler might be able to its job more efficiently.

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SCHED_DEADLINE returns

Posted Apr 12, 2012 19:24 UTC (Thu) by dlang (guest, #313) [Link] (1 responses)

two problems

1. how can the application know this? (the time will vary depending on how well caching works)

2. what do you do with an application that ends up using more than it claimed it would?

SCHED_DEADLINE returns

Posted Apr 12, 2012 19:39 UTC (Thu) by corbet (editor, #1) [Link]

Of course, deadline scheduling depends on exactly this: an application must declare a worst-case execution time along with its deadline. Knowing what the WCET should be is, of course, not a small problem; it's currently fodder for a number of academic careers, I think. Usual practice, I suspect, is to determine it empirically.

As for what happens if you blow the WCET: the deadline scheduler just freezes you out until the next scheduling period starts.