Re: [rfc][patch 2/3] slab: introduce SMP alignment

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From: Christoph Lameter
Date: Monday, March 3, 2008 - 2:23 pm

On Mon, 3 Mar 2008, Pekka Enberg wrote:


AFAICT it follows SLAB semantics. The only small difference is for objects 
small than cache_line_size() / 2 where SLUB does not bother to align to a 
fraction of a cacheline since we are already placing multile object into a 
cacheline. We effectively have made the decision to give up the 
organization of objects in separatate cache lines.

Lets say you have a 64 byte cache line size. Then the alignment can be 
as follows. (8 byte alignment is the basic alignment requirement).

Objsize	[C	SLAB	SLUB
-----------------------------
33 .. 64	64	64
32		32	32
24		32	24	-> 3 object per cacheline sizes = 72 so overlap.
16		16	16
8		8	8

So there is only one difference for 24 byte sizes slabs.


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Messages in current thread:
[rfc][patch 2/3] slab: introduce SMP alignment, Nick Piggin, (Mon Mar 3, 2:35 am)
[rfc][patch 3/3] use SLAB_ALIGN_SMP, Nick Piggin, (Mon Mar 3, 2:36 am)
Re: [rfc][patch 3/3] use SLAB_ALIGN_SMP, Eric Dumazet, (Mon Mar 3, 2:53 am)
Re: [rfc][patch 3/3] use SLAB_ALIGN_SMP, Nick Piggin, (Mon Mar 3, 5:41 am)
Re: [rfc][patch 3/3] use SLAB_ALIGN_SMP, Eric Dumazet, (Mon Mar 3, 6:00 am)
Re: [rfc][patch 3/3] use SLAB_ALIGN_SMP, Nick Piggin, (Mon Mar 3, 6:46 am)
Re: [rfc][patch 3/3] use SLAB_ALIGN_SMP, Pekka Enberg, (Mon Mar 3, 6:53 am)
Re: [rfc][patch 3/3] use SLAB_ALIGN_SMP, Eric Dumazet, (Mon Mar 3, 7:15 am)
Re: [rfc][patch 2/3] slab: introduce SMP alignment, Christoph Lameter, (Mon Mar 3, 12:06 pm)
Re: [rfc][patch 1/3] slub: fix small HWCACHE_ALIGN alignment, Christoph Lameter, (Mon Mar 3, 12:08 pm)
Re: [rfc][patch 3/3] use SLAB_ALIGN_SMP, Christoph Lameter, (Mon Mar 3, 12:09 pm)
Re: [rfc][patch 3/3] use SLAB_ALIGN_SMP, Christoph Lameter, (Mon Mar 3, 12:10 pm)
Re: [rfc][patch 2/3] slab: introduce SMP alignment, Nick Piggin, (Mon Mar 3, 1:03 pm)
Re: [rfc][patch 2/3] slab: introduce SMP alignment, Christoph Lameter, (Mon Mar 3, 1:09 pm)
Re: [rfc][patch 3/3] use SLAB_ALIGN_SMP, Nick Piggin, (Mon Mar 3, 1:10 pm)
Re: [rfc][patch 1/3] slub: fix small HWCACHE_ALIGN alignment, Christoph Lameter, (Mon Mar 3, 1:10 pm)
Re: [rfc][patch 2/3] slab: introduce SMP alignment, Nick Piggin, (Mon Mar 3, 1:12 pm)
Re: [rfc][patch 3/3] use SLAB_ALIGN_SMP, Christoph Lameter, (Mon Mar 3, 1:12 pm)
Re: [rfc][patch 2/3] slab: introduce SMP alignment, Christoph Lameter, (Mon Mar 3, 1:17 pm)
Re: [rfc][patch 3/3] use SLAB_ALIGN_SMP, Nick Piggin, (Mon Mar 3, 1:18 pm)
Re: [rfc][patch 2/3] slab: introduce SMP alignment, Nick Piggin, (Mon Mar 3, 1:24 pm)
Re: [rfc][patch 2/3] slab: introduce SMP alignment, Pekka Enberg, (Mon Mar 3, 1:41 pm)
Re: [rfc][patch 3/3] use SLAB_ALIGN_SMP, Christoph Lameter, (Mon Mar 3, 2:14 pm)
Re: [rfc][patch 1/3] slub: fix small HWCACHE_ALIGN alignment, Christoph Lameter, (Mon Mar 3, 2:16 pm)
Re: [rfc][patch 2/3] slab: introduce SMP alignment, Christoph Lameter, (Mon Mar 3, 2:23 pm)
Re: [rfc][patch 2/3] slab: introduce SMP alignment, Christoph Lameter, (Mon Mar 3, 2:31 pm)
Re: [rfc][patch 1/3] slub: fix small HWCACHE_ALIGN alignment, Christoph Lameter, (Mon Mar 3, 2:32 pm)
Re: [rfc][patch 2/3] slab: introduce SMP alignment, Nick Piggin, (Tue Mar 4, 5:16 pm)
Re: [rfc][patch 1/3] slub: fix small HWCACHE_ALIGN alignment, Christoph Lameter, (Wed Mar 5, 1:56 pm)
Re: [rfc][patch 1/3] slub: fix small HWCACHE_ALIGN alignment, Christoph Lameter, (Wed Mar 5, 2:06 pm)
Re: [rfc][patch 1/3] slub: fix small HWCACHE_ALIGN alignment, Christoph Lameter, (Thu Mar 6, 3:53 pm)
Re: [rfc][patch 1/3] slub: fix small HWCACHE_ALIGN alignment, Christoph Lameter, (Thu Mar 6, 3:56 pm)
Re: [rfc][patch 1/3] slub: fix small HWCACHE_ALIGN alignment, Christoph Lameter, (Thu Mar 6, 7:20 pm)
Re: [rfc][patch 1/3] slub: fix small HWCACHE_ALIGN alignment, Christoph Lameter, (Thu Mar 6, 7:26 pm)
Re: [rfc][patch 1/3] slub: fix small HWCACHE_ALIGN alignment, Christoph Lameter, (Thu Mar 6, 7:27 pm)
Re: [rfc][patch 1/3] slub: fix small HWCACHE_ALIGN alignment, Christoph Lameter, (Thu Mar 6, 7:33 pm)
Re: [rfc][patch 1/3] slub: fix small HWCACHE_ALIGN alignment, Christoph Lameter, (Thu Mar 6, 7:54 pm)
Re: [rfc][patch 1/3] slub: fix small HWCACHE_ALIGN alignment, Christoph Lameter, (Thu Mar 6, 8:18 pm)
Re: [rfc][patch 1/3] slub: fix small HWCACHE_ALIGN alignment, Christoph Lameter, (Thu Mar 6, 8:58 pm)
Re: [rfc][patch 2/3] slab: introduce SMP alignment, Nick Piggin, (Thu Mar 6, 9:37 pm)
Re: [rfc][patch 2/3] slab: introduce SMP alignment, Christoph Lameter, (Thu Mar 6, 10:11 pm)
Re: [rfc][patch 2/3] slab: introduce SMP alignment, Nick Piggin, (Thu Mar 6, 10:19 pm)
Re: [rfc][patch 2/3] slab: introduce SMP alignment, Christoph Lameter, (Thu Mar 6, 10:26 pm)
Re: [rfc][patch 2/3] slab: introduce SMP alignment, Nick Piggin, (Thu Mar 6, 10:37 pm)
Re: [rfc][patch 2/3] slab: introduce SMP alignment, Nick Piggin, (Tue Mar 11, 12:13 am)
Re: [rfc][patch 2/3] slab: introduce SMP alignment, Christoph Lameter, (Tue Mar 11, 11:21 pm)