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From: Andrew Morton <akpm@osdl.org>
To: Ingo Molnar <mingo@elte.hu>
Cc: hugh@veritas.com, linux-kernel@vger.kernel.org, torvalds@osdl.org
Subject: Re: [PATCH 01/15] mm: poison struct page for ptlock
Date: Thu, 10 Nov 2005 04:26:13 -0800	[thread overview]
Message-ID: <20051110042613.7a585dec.akpm@osdl.org> (raw)
In-Reply-To: <20051110120624.GB32672@elte.hu>

Ingo Molnar <mingo@elte.hu> wrote:
>
> yuck. What is the real problem btw?

Well.  One problem is that spinlocks now take two words...

But apart from that, the problem at hand is that we want to embed a
spinlock in struct page, and the size of the spinlock varies a lot according
to config.  The only >wordsize version we really care about is
CONFIG_PREEMPT, NR_CPUS >= 4.  (which distros don't ship...)

> AFAICS there's enough space for a 
>  2-word spinlock in struct page for pagetables.

spinlocks get a lot bigger than that with CONFIG_DEBUG_SPINLOCK.

> We really dont want to 
>  rewrite spinlocks (or remove features) just to keep gcc 2.95 supported 
>  for some more time. In fact, is there any 2.6 based distro that uses gcc 
>  2.95?

I think some of the debian derivates might.  But who knows?

  reply	other threads:[~2005-11-10 12:26 UTC|newest]

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-11-10  1:42 [PATCH 00/15] mm: struct page lock and counts Hugh Dickins
2005-11-10  1:43 ` [PATCH 01/15] mm: poison struct page for ptlock Hugh Dickins
2005-11-10  2:10   ` Andrew Morton
2005-11-10  2:22     ` Hugh Dickins
2005-11-10  2:56       ` Andrew Morton
2005-11-10  2:58         ` Andrew Morton
2005-11-10 11:28           ` Ingo Molnar
2005-11-10 12:06         ` Ingo Molnar
2005-11-10 12:26           ` Andrew Morton [this message]
2005-11-10 21:37             ` Christoph Lameter
2005-11-10 21:52               ` Christoph Hellwig
2005-11-11 10:46                 ` Ingo Molnar
2005-11-12 23:48             ` Adrian Bunk
2005-11-10 12:35           ` Hugh Dickins
2005-11-10 12:51             ` Andrew Morton
2005-11-10 13:29               ` Hugh Dickins
2005-11-10 15:00                 ` Ingo Molnar
2005-11-10 15:38                   ` Hugh Dickins
2005-11-10 19:49                 ` Andrew Morton
2005-11-10 19:56                   ` Linus Torvalds
2005-11-11  0:10                     ` Russell King
2005-11-12  6:27                     ` Benjamin Herrenschmidt
2005-11-11 15:02                   ` Hugh Dickins
2005-11-15 18:49     ` Andrew Morton
2005-11-15 19:51       ` Hugh Dickins
2005-11-15 20:05         ` Andrew Morton
2005-11-10  1:44 ` [PATCH 02/15] mm: revert page_private Hugh Dickins
2005-11-10  1:46 ` [PATCH 03/15] mm reiser4: " Hugh Dickins
2005-11-10  1:47 ` [PATCH 04/15] mm: update split ptlock Kconfig Hugh Dickins
2005-11-10  1:48 ` [PATCH 05/15] mm: unbloat get_futex_key Hugh Dickins
2005-11-10  1:50 ` [PATCH 06/15] mm: remove ppc highpte Hugh Dickins
2005-11-10  1:52   ` Benjamin Herrenschmidt
2005-11-10  1:55   ` Paul Mackerras
2005-11-10  2:46     ` Hugh Dickins
2005-11-10  1:51 ` [PATCH 07/15] mm: powerpc ptlock comments Hugh Dickins
2005-11-10  1:53 ` [PATCH 08/15] mm: powerpc init_mm without ptlock Hugh Dickins
2005-11-10  1:56 ` [PATCH 09/15] mm: fill arch atomic64 gaps Hugh Dickins
2005-11-10 13:38   ` Andi Kleen
2005-11-10 15:19     ` Hugh Dickins
2005-11-10  1:57 ` [PATCH 10/15] mm: atomic64 page counts Hugh Dickins
2005-11-10  2:16   ` Andrew Morton
2005-11-10  2:33     ` Hugh Dickins
2005-11-10  3:01       ` Andrew Morton
2005-11-10 21:43         ` Christoph Lameter
2005-11-10 21:53           ` Andrew Morton
2005-11-11 15:25             ` Hugh Dickins
2005-11-11 18:03               ` Christoph Lameter
2005-11-10  2:00 ` [PATCH 11/15] mm: long " Hugh Dickins
2005-11-10  2:01 ` [PATCH 12/15] mm reiser4: " Hugh Dickins
2005-11-10  2:03 ` [PATCH 13/15] mm: get_user_pages check count Hugh Dickins
2005-11-10  2:08 ` [PATCH 14/15] mm: inc_page_table_pages check max Hugh Dickins
2005-11-10  2:09 ` [PATCH 15/15] mm: remove install_page limit Hugh Dickins

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