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List:       linux-rt-users
Subject:    Re: Help needed to implement parameter in SCHED_DEADLINE policy
From:       Valdis.Kletnieks () vt ! edu
Date:       2014-12-27 20:19:47
Message-ID: 45259.1419711587 () turing-police ! cc ! vt ! edu
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On Sun, 28 Dec 2014 00:09:36 +0530, Chanchal Paul said:
> their DEADLINE. I dont want to disturb that order. If a scheduler
> picks up a task which is computationally intensive and lets it run
> then due to its thermal characteristic it may heat up processor so
> much that eventually a hardware DTM or a frequency scaling occurs and
> the system slows down as a effect.

This is properly the domain of CPU governors, not schedulers. Modern Intel
chipsets with the Turbo feature will dynamically up-throttle to whatever the
cooling budget allows, and if you have an older chipset that doesn't do that,
you're better off creating a custom governor that doesn't allow selection of
the highest CPU frequenc(y|ies) that exceed the current cooling budget

Note that this gets tricky on multi-core sockets, as activity on other
cores affects the cooling budget for the core you're scheduling onto.

And if your hardware is throwing actual thermal shutdown events, you have
bigger problems that scheduler hacks won't help.



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