Re: [bisected] pre-3.16 regression on open() scalability

From: josh
Date: Thu Jun 19 2014 - 17:32:15 EST


On Thu, Jun 19, 2014 at 04:16:34PM -0500, Christoph Lameter wrote:
> This looks very much like the CONFIG_PREEMPT problem in not so
> extreme form. Maybe we need to add another config option:
>
> CONFIG_REALLY_REALLY_NO_PREEMPT
>
> to get the fastest code possible and those cond_rescheds removed from the
> critical paths?
>
> Or better
>
> CONFIG_PREEMPT_HALF_WAY
>
> to enable those cond_rescheds.

That much actually does seem quite reasonable: making cond_resched() do
non-trivial work ought to have a config option to disable it.
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