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

From: Andi Kleen
Date: Tue Jun 17 2014 - 20:15:24 EST


> It also ends up eating a new cacheline in a bunch of pretty hot paths.
> It would be nice to be able to keep the fast path part of this as at
> least read-only.
>
> Could we do something (functionally) like the attached patch? Instead
> of counting cond_resched() calls, we could just specify some future time
> by which we want have a quiescent state. We could even push the time to
> be something _just_ before we would have declared a stall.

I still think it's totally the wrong place. cond_resched() is in so
many fast paths (every lock, every allocation). It just doesn't
make sense to add non essential things like this to it.

I would be rather to just revert the original patch.

-Andi
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