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SubjectRe: [bisected] pre-3.16 regression on open() scalability
On Thu, Jun 19, 2014 at 02:32:03PM -0700, josh@joshtriplett.org wrote:
> 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.

I am putting together patches based on Eric Dumazet's suggestion and on a
variant of the above approach. However, I do expect the distros to starve
to death between those two bales of hay. But perhaps the actual patches
will inspire a bit of light to go with this thread's heat and smoke.

Thanx, Paul



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