ULE vs. 4BSD in RELENG_7

Josh Carroll josh.carroll at gmail.com
Wed Oct 24 12:29:36 PDT 2007

> Your tests with ffmpeg threads vs processes probably is triggering more
> context switches due to lock contention in the kernel in the threads case.
> This is also likely the problem with some super-smack tests.  On each
> context switch 4BSD has an opportunity to perfectly balance the CPUs.  ULE
> does not because it's too costly and hinders other workloads.

Thanks for the response Jeff, I appreciate it. Is this something that
the scheduler can recognize and auto-tune itself for? E.g. have it
recognize the scenario differences and do what 4BSD is doing for cases
such as ffmpeg and what ULE otherwise does in other circumstances? I
guess this would not come without its own overhead, which might defeat
the purpose anyway.

> I don't doubt that we can improve things further.  It will just have to
> wait for another few weeks before I'm able to do much about it.

Thanks again, I do appreciate your work and help. So you're
anticipating nothing can be done at all, or did you mean at the moment
until you get your equipment back and get settled? Or is this
something that would need to be looked at in -current rather than


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