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Date: Sun, 15 Aug 2004 16:55:57 -0700 (PDT)
From: Christoph Lameter <christoph@lameter.com>
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To: Andi Kleen <ak@muc.de>
cc: Christoph Lameter <clameter@sgi.com>, linux-ia64@vger.kernel.org,
       linux-kernel@vger.kernel.org
Subject: Re: page fault fastpath: Increasing SMP scalability by introducing
  pte locks?
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On Mon, 16 Aug 2004, Andi Kleen wrote:

> Christoph Lameter <clameter@sgi.com> writes:
>
> > On Sun, 15 Aug 2004, David S. Miller wrote:
> >
> >>
> >> Is the read lock in the VMA semaphore enough to let you do
> >> the pgd/pmd walking without the page_table_lock?
> >> I think it is, but just checking.
> >
> > That would be great.... May I change the page_table lock to
> > be a read write spinlock instead?
>
> That's probably not a good idea. r/w locks are extremly slow on
> some architectures. Including ia64.

I was thinking about a read write spinlock not an readwrite
semaphore. Look at include/asm-ia64/spinlock.h.
The implementations are almost the same. Are you sure
about this?