Re: [PATCH 1/2] sched/wait: Break up long wake list walk

[Linus Torvalds]

On Fri, Aug 18, 2017 at 12:58 PM, Andi Kleen <ak@xxxxxxxxxxxxxxx> wrote:
>> which is hacky, but there's a rationale for it:
>>
>>  (a) avoid the crazy long wait queues ;)
>>
>>  (b) we know that migration is *supposed* to be CPU-bound (not IO
>> bound), so yielding the CPU and retrying may just be the right thing
>> to do.
>
> So this would degenerate into a spin when the contention is with
> other CPUs?
>
> But then if we guarantee that migration has flat latency curve
> and no long tail it may be reasonable.

Honestly, right now I'd say it's more of a "poath meant purely for
testing with some weak-ass excuse for why it might not be broken".

                 Linus