From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Christoph Lameter <christoph@lameter.com>
Cc: William Lee Irwin III <wli@holomorphy.com>,
"David S. Miller" <davem@davemloft.net>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Anton Blanchard <anton@samba.org>
Subject: Re: [patch 2] mm: speculative get_page
Date: Wed, 29 Jun 2005 09:10:44 +1000 [thread overview]
Message-ID: <42C1D8F4.2010601@yahoo.com.au> (raw)
In-Reply-To: <Pine.LNX.4.62.0506280959100.10511@graphe.net>
Christoph Lameter wrote:
> On Wed, 29 Jun 2005, Nick Piggin wrote:
>
>
>>But nit picking aside, is it true that we need a load barrier before
>>unlock? (store barrier I agree with) The ppc64 changeset in question
>>indicates yes, but I can't quite work out why. There are noises in the
>>archives about this, but I didn't pinpoint a conclusion...
>
>
> A spinlock may be used to read a consistent set of variables. If load
> operations would be moved below the spin_unlock then one may get values
> that have been updated after another process acquired the spinlock.
>
>
Of course, thanks. I was only thinking of the case where loads
were moved from the unlocked into the locked section.
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WARNING: multiple messages have this Message-ID (diff)
From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Christoph Lameter <christoph@lameter.com>
Cc: William Lee Irwin III <wli@holomorphy.com>,
"David S. Miller" <davem@davemloft.net>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Anton Blanchard <anton@samba.org>
Subject: Re: [patch 2] mm: speculative get_page
Date: Wed, 29 Jun 2005 09:10:44 +1000 [thread overview]
Message-ID: <42C1D8F4.2010601@yahoo.com.au> (raw)
In-Reply-To: <Pine.LNX.4.62.0506280959100.10511@graphe.net>
Christoph Lameter wrote:
> On Wed, 29 Jun 2005, Nick Piggin wrote:
>
>
>>But nit picking aside, is it true that we need a load barrier before
>>unlock? (store barrier I agree with) The ppc64 changeset in question
>>indicates yes, but I can't quite work out why. There are noises in the
>>archives about this, but I didn't pinpoint a conclusion...
>
>
> A spinlock may be used to read a consistent set of variables. If load
> operations would be moved below the spin_unlock then one may get values
> that have been updated after another process acquired the spinlock.
>
>
Of course, thanks. I was only thinking of the case where loads
were moved from the unlocked into the locked section.
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next prev parent reply other threads:[~2005-06-28 23:43 UTC|newest]
Thread overview: 106+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-06-27 6:29 [rfc] lockless pagecache Nick Piggin
2005-06-27 6:29 ` 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
2005-06-27 14:12 ` William Lee Irwin III
2005-06-28 0:03 ` Nick Piggin
2005-06-28 0:03 ` Nick Piggin
2005-06-28 0:56 ` Nick Piggin
2005-06-28 0:56 ` Nick Piggin
2005-06-28 1:22 ` William Lee Irwin III
2005-06-28 1:22 ` William Lee Irwin III
2005-06-28 1:42 ` Nick Piggin
2005-06-28 1:42 ` Nick Piggin
2005-06-28 4:06 ` William Lee Irwin III
2005-06-28 4:06 ` William Lee Irwin III
2005-06-28 4:50 ` Nick Piggin
2005-06-28 4:50 ` Nick Piggin
2005-06-28 5:08 ` David S. Miller
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 5:34 ` Nick Piggin
2005-06-28 14:19 ` William Lee Irwin III
2005-06-28 14:19 ` William Lee Irwin III
2005-06-28 15:43 ` Nick Piggin
2005-06-28 15:43 ` Nick Piggin
2005-06-28 17:01 ` Christoph Lameter
2005-06-28 17:01 ` Christoph Lameter
2005-06-28 23:10 ` Nick Piggin [this message]
2005-06-28 23:10 ` Nick Piggin
2005-06-28 21:32 ` Jesse Barnes
2005-06-28 21:32 ` Jesse Barnes
2005-06-28 22:17 ` Christoph Lameter
2005-06-28 22:17 ` Christoph Lameter
2005-06-28 12:45 ` Andy Whitcroft
2005-06-28 12:45 ` Andy Whitcroft
2005-06-28 13:16 ` Nick Piggin
2005-06-28 13:16 ` Nick Piggin
2005-06-28 16:02 ` Dave Hansen
2005-06-28 16:02 ` Dave Hansen
2005-06-29 16:31 ` Pavel Machek
2005-06-29 16:31 ` Pavel Machek
2005-06-29 18:43 ` Dave Hansen
2005-06-29 18:43 ` Dave Hansen
2005-06-29 21:22 ` Pavel Machek
2005-06-29 21:22 ` Pavel Machek
2005-06-29 16:31 ` 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 6:43 ` Nick Piggin
2005-06-27 7:13 ` Andi Kleen
2005-06-27 7:13 ` Andi Kleen
2005-06-27 7:33 ` VFS scalability Nick Piggin
2005-06-27 7:33 ` Nick Piggin
2005-06-27 7:44 ` Andi Kleen
2005-06-27 7:44 ` Andi Kleen
2005-06-27 8:03 ` Nick Piggin
2005-06-27 8:03 ` Nick Piggin
2005-06-27 7:46 ` [rfc] lockless pagecache Andrew Morton
2005-06-27 7:46 ` Andrew Morton
2005-06-27 8:02 ` Nick Piggin
2005-06-27 8:02 ` Nick Piggin
2005-06-27 8:15 ` Andrew Morton
2005-06-27 8:15 ` Andrew Morton
2005-06-27 8:28 ` Nick Piggin
2005-06-27 8:28 ` Nick Piggin
2005-06-27 8:56 ` Lincoln Dale
2005-06-27 8:56 ` Lincoln Dale
2005-06-27 9:04 ` Nick Piggin
2005-06-27 9:04 ` Nick Piggin
2005-06-27 18:14 ` Chen, Kenneth W
2005-06-27 18:14 ` Chen, Kenneth W
2005-06-27 18:50 ` Badari Pulavarty
2005-06-27 18:50 ` Badari Pulavarty
2005-06-27 19:05 ` Chen, Kenneth W
2005-06-27 19:05 ` Chen, Kenneth W
2005-06-27 19:22 ` Christoph Lameter
2005-06-27 19:22 ` Christoph Lameter
2005-06-27 19:42 ` Chen, Kenneth W
2005-06-27 19:42 ` Chen, Kenneth W
2005-07-05 15:11 ` Sonny Rao
2005-07-05 15:11 ` Sonny Rao
2005-07-05 15:31 ` Martin J. Bligh
2005-07-05 15:31 ` Martin J. Bligh
2005-07-05 15:37 ` Sonny Rao
2005-07-05 15:37 ` Sonny Rao
2005-06-27 13:17 ` Benjamin LaHaise
2005-06-27 13:17 ` Benjamin LaHaise
2005-06-28 0:32 ` Nick Piggin
2005-06-28 0:32 ` Nick Piggin
2005-06-28 1:26 ` William Lee Irwin III
2005-06-28 1:26 ` William Lee Irwin III
2005-06-27 14:08 ` Martin J. Bligh
2005-06-27 14:08 ` Martin J. Bligh
2005-06-27 17:49 ` Christoph Lameter
2005-06-27 17:49 ` Christoph Lameter
2005-06-29 10:49 ` Hirokazu Takahashi
2005-06-29 10:49 ` Hirokazu Takahashi
2005-06-29 11:38 ` Nick Piggin
2005-06-29 11:38 ` Nick Piggin
2005-06-30 3:32 ` Hirokazu Takahashi
2005-06-30 3:32 ` Hirokazu Takahashi
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