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Message-Id: <20070515233239.335bd4ed.akpm@linux-foundation.org>
Date: Tue, 15 May 2007 23:32:39 -0700
From: Andrew Morton <akpm@...ux-foundation.org>
To: Christoph Lameter <clameter@....com>
Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: Slab allocators: Define common size limitations
On Tue, 15 May 2007 23:15:24 -0700 (PDT) Christoph Lameter <clameter@....com> wrote:
> Currently we have a maze of configuration variables that determine
> the maximum slab size. Worst of all it seems to vary between SLAB and SLUB.
>
> So define a common maximum size for kmalloc. For conveniences sake
> we use the maximum size ever supported which is 32 MB. We limit the maximum
> size to a lower limit if MAX_ORDER does not allow such large allocations.
>
> For many architectures this patch will have the effect of adding large
> kmalloc sizes. x86_64 adds 5 new kmalloc sizes. So a small amount
> of memory will be needed for these caches (contemporary SLAB has dynamically
> sizeable node and cpu structure so the waste is less than in the past)
>
> Most architectures will then be able to allocate object with sizes up to
> MAX_ORDER. We have had repeated breakage (in fact whenever we doubled the
> number of supported processors) on IA64 because one or the other struct
> grew beyond what the slab allocators supported. This will avoid future
> issues and f.e. avoid fixes for 2k and 4k cpu support.
>
> CONFIG_LARGE_ALLOCS is no longer necessary so drop it.
>
> Signed-off-by: Christoph Lameter <clameter@....com>
>
> ---
> arch/blackfin/Kconfig | 8 --------
> arch/frv/Kconfig | 8 --------
> arch/m68knommu/Kconfig | 8 --------
> arch/v850/Kconfig | 8 --------
> include/linux/kmalloc_sizes.h | 20 +++++++++++++++-----
> include/linux/slab.h | 15 +++++++++++++++
> include/linux/slub_def.h | 19 ++-----------------
> mm/slab.c | 19 ++-----------------
> 8 files changed, 34 insertions(+), 71 deletions(-)
rofl. Really we shouldn't put this into 2.6.22, but it turfs out so much
crap that it's hard to justify holding it back.
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