Re: [PATCH 2.6.21-rc3-mm2 3/4] futex_requeue_pi optimization

Pierre Peiffer
2007-03-20T16:33:31Z

Peter Zijlstra a écrit :

>
> Unfortunately not, nonlinear vmas don't have a linear relation between
> address and offset. What you would need to do is do a linear walk of the
> page tables. But even that might not suffice if nonlinear vmas may form
> a non-injective, surjective mapping.
>
> /me checks..
>
> Hmm, yes that seems valid, so in general, this reverse mapping does not
> uniquely exist for non-linear vmas. :-(
>
> What to do... disallow futexes in nonlinear mappings,

> store the address in the key? <<

That seems to be the only solution... :-/

>
> the vma_prio_tree would be able to give all vmas associated with a
> mapping.
>

Thanks for your help.

--
Pierre