Re: [patch] slab: always follow arch requested alignments

[Pekka J Enberg <penberg@cs.Helsinki.FI>]

On 7/26/06, Christoph Lameter <clameter@sgi.com> wrote:
> > > Your patch only deals with ARCH_SLAB_MINALIGN. kmem_cache_create() never
> > > uses ARCH_KMALLOC_MINALIGN only kmem_cache_init() does by passing it to
> > > kmem_cache_create.  ARCH_KMALLOC_MINALIGN will still be ignored.
 
On Wed, 26 Jul 2006, Pekka Enberg wrote:
> > Yes, in which case the caller mandated align will be, well,
> > ARCH_KMALLOC_MINALIGN. The patch changes kmem_cache_create to respect
> > caller mandated alignment too.

On Wed, 26 Jul 2006, Christoph Lameter wrote:
> As far as I understood Heiko s390 does not set ARCH_SLAB_MINALIGN
> because they do not want alignent for all caches.

Correct. Heiko sets ARCH_KMALLOC_MINALIGN which will be passed as the 
'align' parameter to kmem_cache_create -- also known as 'caller mandated 
alignment.'

My patch changes the code so that, if either architecture or 
caller mandated alignment is greater than BYTES_PER_WORD, 
kmem_cache_create will disable debugging. Do you now see why my patch is 
in fact _not_ ignoring ARCH_KMALLOC_MINALIGN, but instead respecting that.

			Pekka
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