From: Jesse Barnes <jbarnes@virtuousgeek.org>
To: "David S. Miller" <davem@davemloft.net>
Cc: nickpiggin@yahoo.com.au, wli@holomorphy.com,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [patch 2] mm: speculative get_page
Date: Tue, 28 Jun 2005 14:32:30 -0700 [thread overview]
Message-ID: <200506281432.30868.jbarnes@virtuousgeek.org> (raw)
In-Reply-To: <20050627.220827.21920197.davem@davemloft.net>
On Monday, June 27, 2005 10:08 pm, David S. Miller wrote:
> From: Nick Piggin <nickpiggin@yahoo.com.au>
> Subject: Re: [patch 2] mm: speculative get_page
> Date: Tue, 28 Jun 2005 14:50:31 +1000
>
> > William Lee Irwin III wrote:
> > >On Tue, Jun 28, 2005 at 11:42:16AM +1000, Nick Piggin wrote:
> > >
> > >spin_unlock() does not imply a memory barrier.
> >
> > Intriguing...
>
> BTW, I disagree with this assertion. spin_unlock() does imply a
> memory barrier.
>
> All memory operations before the release of the lock must execute
> before the lock release memory operation is globally visible.
On ia64 at least, the unlock is only a one way barrier. The store to
realease the lock uses release semantics (since the lock is declared
volatile), which implies that prior stores are visible before the
unlock occurs, but subsequent accesses can 'float up' above the unlock.
See http://www.gelato.unsw.edu.au/linux-ia64/0304/5122.html for some
more details.
Jesse
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next prev parent reply other threads:[~2005-06-28 21:32 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-06-27 6:29 [rfc] lockless pagecache Nick Piggin
2005-06-27 6:32 ` [patch 1] mm: PG_free flag Nick Piggin
2005-06-27 6:32 ` [patch 2] mm: speculative get_page Nick Piggin
2005-06-27 6:33 ` [patch 3] radix tree: lookup_slot Nick Piggin
2005-06-27 6:34 ` [patch 4] radix tree: lockless readside Nick Piggin
2005-06-27 6:34 ` [patch 5] mm: lockless pagecache lookups Nick Piggin
2005-06-27 6:35 ` [patch 6] mm: spinlock tree_lock Nick Piggin
2005-06-27 14:12 ` [patch 2] mm: speculative get_page William Lee Irwin III
2005-06-28 0:03 ` Nick Piggin
2005-06-28 0:56 ` Nick Piggin
2005-06-28 1:22 ` William Lee Irwin III
2005-06-28 1:42 ` Nick Piggin
2005-06-28 4:06 ` William Lee Irwin III
2005-06-28 4:50 ` Nick Piggin
2005-06-28 5:08 ` [patch 2] mm: speculative get_page, " David S. Miller, Nick Piggin
2005-06-28 5:34 ` Nick Piggin
2005-06-28 14:19 ` William Lee Irwin III
2005-06-28 15:43 ` Nick Piggin
2005-06-28 17:01 ` Christoph Lameter
2005-06-28 23:10 ` Nick Piggin
2005-06-28 21:32 ` Jesse Barnes [this message]
2005-06-28 22:17 ` Christoph Lameter
2005-06-28 12:45 ` Andy Whitcroft
2005-06-28 13:16 ` Nick Piggin
2005-06-28 16:02 ` Dave Hansen
2005-06-29 16:31 ` Pavel Machek
2005-06-29 18:43 ` Dave Hansen
2005-06-29 21:22 ` Pavel Machek
2005-06-29 16:31 ` Pavel Machek
2005-06-27 6:43 ` VFS scalability (was: [rfc] lockless pagecache) Nick Piggin
2005-06-27 7:13 ` Andi Kleen
2005-06-27 7:33 ` VFS scalability Nick Piggin
2005-06-27 7:44 ` Andi Kleen
2005-06-27 8:03 ` Nick Piggin
2005-06-27 7:46 ` [rfc] lockless pagecache Andrew Morton
2005-06-27 8:02 ` Nick Piggin
2005-06-27 8:15 ` Andrew Morton
2005-06-27 8:28 ` Nick Piggin
2005-06-27 8:56 ` Lincoln Dale
2005-06-27 9:04 ` Nick Piggin
2005-06-27 18:14 ` Chen, Kenneth W
2005-06-27 18:50 ` Badari Pulavarty
2005-06-27 19:05 ` Chen, Kenneth W
2005-06-27 19:22 ` Christoph Lameter
2005-06-27 19:42 ` Chen, Kenneth W
2005-07-05 15:11 ` Sonny Rao
2005-07-05 15:31 ` Martin J. Bligh
2005-07-05 15:37 ` Sonny Rao
2005-06-27 13:17 ` Benjamin LaHaise
2005-06-28 0:32 ` Nick Piggin
2005-06-28 1:26 ` William Lee Irwin III
2005-06-27 14:08 ` Martin J. Bligh
2005-06-27 17:49 ` Christoph Lameter
2005-06-29 10:49 ` Hirokazu Takahashi
2005-06-29 11:38 ` Nick Piggin
2005-06-30 3:32 ` Hirokazu Takahashi
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