From: Ezequiel Garcia <elezegarcia@gmail.com>
To: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>, Joonsoo Kim <js1304@gmail.com>,
Glauber Costa <glommer@parallels.com>,
linux-mm@kvack.org, David Rientjes <rientjes@google.com>,
Tim Bird <tim.bird@am.sony.com>
Subject: Re: REN2 [07/13] Common constants for kmalloc boundaries
Date: Sat, 2 Feb 2013 15:00:11 -0300 [thread overview]
Message-ID: <CALF0-+VGnhL0B5nuqJUYCEzKRxzzxJAWzT2x1SumVRmVapdLRg@mail.gmail.com> (raw)
In-Reply-To: <0000013c25e260c8-aeaa555f-3466-4c01-8e81-9891429850b2-000000@email.amazonses.com>
Hi Christoph,
On Thu, Jan 10, 2013 at 4:14 PM, Christoph Lameter <cl@linux.com> wrote:
> Standardize the constants that describe the smallest and largest
> object kept in the kmalloc arrays for SLAB and SLUB.
>
> Differentiate between the maximum size for which a slab cache is used
> (KMALLOC_MAX_CACHE_SIZE) and the maximum allocatable size
> (KMALLOC_MAX_SIZE, KMALLOC_MAX_ORDER).
>
> Signed-off-by: Christoph Lameter <cl@linux.com>
>
> Index: linux/include/linux/slab.h
> ===================================================================
> --- linux.orig/include/linux/slab.h 2013-01-10 09:42:25.640301677 -0600
> +++ linux/include/linux/slab.h 2013-01-10 09:43:40.857456229 -0600
> @@ -163,7 +163,12 @@ struct kmem_cache {
> #else /* CONFIG_SLOB */
>
> /*
> - * The largest kmalloc size supported by the slab allocators is
> + * Kmalloc array related definitions
> + */
> +
> +#ifdef CONFIG_SLAB
> +/*
> + * The largest kmalloc size supported by the SLAB allocators is
> * 32 megabyte (2^25) or the maximum allocatable page order if that is
> * less than 32 MB.
> *
> @@ -173,9 +178,24 @@ struct kmem_cache {
> */
> #define KMALLOC_SHIFT_HIGH ((MAX_ORDER + PAGE_SHIFT - 1) <= 25 ? \
> (MAX_ORDER + PAGE_SHIFT - 1) : 25)
> +#define KMALLOC_SHIFT_MAX KMALLOC_SHIFT_HIGH
> +#define KMALLOC_SHIFT_LOW 5
> +#else
> +/*
> + * SLUB allocates up to order 2 pages directly and otherwise
> + * passes the request to the page allocator.
> + */
> +#define KMALLOC_SHIFT_HIGH (PAGE_SHIFT + 1)
> +#define KMALLOC_SHIFT_MAX (MAX_ORDER + PAGE_SHIFT)
> +#define KMALLOC_SHIFT_LOW 3
> +#endif
>
Why do we need to distinguish SLAB from SLUB here?
I mean: why do we need to maintain 32 bytes as the smallest kmalloc cache?
Thanks,
--
Ezequiel
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next prev parent reply other threads:[~2013-02-02 18:00 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20130110190027.780479755@linux.com>
2013-01-10 19:00 ` REN2 [01/13] slab_common: Use proper formatting specs for unsigned size_t Christoph Lameter
2013-01-10 19:00 ` REN2 [02/13] Move kmalloc related function defs Christoph Lameter
2013-01-10 19:12 ` REN2 [05/13] slab: Common name for the per node structures Christoph Lameter
2013-01-10 19:12 ` REN2 [08/13] Common definition for the array of kmalloc caches Christoph Lameter
2013-01-10 19:12 ` REN2 [09/13] Common function to create the kmalloc array Christoph Lameter
2013-01-11 7:23 ` Joonsoo Kim
2013-01-14 14:46 ` Christoph Lameter
[not found] ` <alpine.DEB.2.02.1301140843010.27095@gentwo.org>
2013-01-14 19:50 ` Christoph Lameter
2013-01-10 19:14 ` REN2 [10/13] stat: Use size_t for sizes instead of unsigned Christoph Lameter
2013-01-10 19:14 ` REN2 [04/13] slab: Use common kmalloc_index/kmalloc_size functions Christoph Lameter
2013-01-10 19:14 ` REN2 [11/13] Common Kmalloc cache determination Christoph Lameter
2013-01-10 19:14 ` REN2 [03/13] Common kmalloc slab index determination Christoph Lameter
2013-01-10 19:14 ` REN2 [13/13] Common definition for kmem_cache_node Christoph Lameter
2013-01-10 19:14 ` REN2 [12/13] slab: Rename list3/l3 to node Christoph Lameter
2013-01-10 19:14 ` REN2 [07/13] Common constants for kmalloc boundaries Christoph Lameter
2013-02-02 18:00 ` Ezequiel Garcia [this message]
2013-02-04 19:36 ` Christoph Lameter
2013-01-10 19:14 ` REN2 [06/13] slab: rename nodelists to node Christoph Lameter
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