Re: [PATCH] SLUB The unqueued slab allocator V3

[David Miller <davem@davemloft.net>]

> On Wed, 28 Feb 2007, David Miller wrote:
> 
> > Arguably SLAB_HWCACHE_ALIGN and SLAB_MUST_HWCACHE_ALIGN should
> > not be set here, but SLUBs change in semantics in this area
> > could cause similar grief in other areas, an audit is probably
> > in order.
> > 
> > The above example was from sparc64, but x86 does the same thing
> > as probably do other platforms which use SLAB for pagetables.
> 
> Maybe this will address these concerns?
> 
> Index: linux-2.6.21-rc2/mm/slub.c
> ===================================================================
> --- linux-2.6.21-rc2.orig/mm/slub.c	2007-02-28 16:54:23.000000000 -0800
> +++ linux-2.6.21-rc2/mm/slub.c	2007-02-28 17:03:54.000000000 -0800
> @@ -1229,8 +1229,10 @@ static int calculate_order(int size)
>  static unsigned long calculate_alignment(unsigned long flags,
>  		unsigned long align)
>  {
> -	if (flags & (SLAB_MUST_HWCACHE_ALIGN|SLAB_HWCACHE_ALIGN))
> +	if (flags & SLAB_HWCACHE_ALIGN)
>  		return L1_CACHE_BYTES;
> +	if (flags & SLAB_MUST_HWCACHE_ALIGN)
> +		return max(align, (unsigned long)L1_CACHE_BYTES);
>  
>  	if (align < ARCH_SLAB_MINALIGN)
>  		return ARCH_SLAB_MINALIGN;

It would achiever parity with existing SLAB behavior, sure.

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