Re: [patch V2 2/7] futex: Hash private futexes per process

From: Peter Zijlstra
Date: Mon May 30 2016 - 10:02:26 EST

On Mon, May 30, 2016 at 03:59:51PM +0200, Sebastian Andrzej Siewior wrote:
> On 05/30/2016 03:49 PM, Peter Zijlstra wrote:
> >> The same thing can happen within a Task if you take my story from above
> >> and replace task with thread. Completely understood.
> >
> > Right; so I don't see the point of PREALLOCATE_HASH to cater for RT
> > workloads if it still doesn't guarantee anything, esp. if the failure
> > case is silent and obscure.
> So what do you suggest? Adding trace points in order to learn about
> possible collisions or using tickets (on top of this) to guarantee
> being collision free?

I have no idea about the ticket stuff, i've not seen it. But yes, you
need to somehow guarantee no collisions.