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From: Pierre Peiffer <pierre.peiffer@bull.net>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: mingo@elte.hu, drepper@redhat.com, linux-kernel@vger.kernel.org,
	Jean-Pierre Dion <jean-pierre.dion@bull.net>
Subject: Re: [PATCH 2.6.21-rc3-mm2 3/4] futex_requeue_pi optimization
Date: Tue, 20 Mar 2007 17:32:11 +0100	[thread overview]
Message-ID: <46000C8B.1090600@bull.net> (raw)
In-Reply-To: <1174406134.16478.37.camel@twins>

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

  reply	other threads:[~2007-03-20 16:33 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-03-13  9:52 [PATCH 2.6.21-rc3-mm2 0/4] Futexes functionalities and improvements Pierre.Peiffer
2007-03-13  9:52 ` [PATCH 2.6.21-rc3-mm2 1/4] futex priority based wakeup Pierre.Peiffer
2007-03-13  9:52 ` [PATCH 2.6.21-rc3-mm2 2/4] Make futex_wait() use an hrtimer for timeout Pierre.Peiffer
2007-03-13  9:52 ` [PATCH 2.6.21-rc3-mm2 3/4] futex_requeue_pi optimization Pierre.Peiffer
2007-03-16 10:14   ` Peter Zijlstra
2007-03-20 15:32     ` Pierre Peiffer
2007-03-20 15:55       ` Peter Zijlstra
2007-03-20 16:32         ` Pierre Peiffer [this message]
2007-03-13  9:52 ` [PATCH 2.6.21-rc3-mm2 4/4] sys_futex64 : allows 64bit futexes Pierre.Peiffer
2007-03-15 19:07   ` Andrew Morton
2007-03-15 19:12     ` Ulrich Drepper
2007-03-15 19:31       ` Andrew Morton
2007-03-15 19:37         ` Ulrich Drepper

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