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SubjectRe: + fix-spellings-of-slab-allocator-section-in-init-kconfig.patch added to -mm tree
Christoph Lameter wrote:
> On Tue, 8 May 2007, Matt Mackall wrote:
>
>
>>>>Yes. It can in fact put 512 8-byte objects in a 4k page. More
>>>
>>>So can SLUB.
>>
>>Not without at least a bit per-object of overhead. So you can either
>>fit 512 objects in 4160 bytes or 504 objects in 4k.
>
>
> Slub uses a linked list pointer in the page struct which is NULL if all
> objects are allocated. There is no bit per object overhead.
>
>
>>For the kmalloc case, we do have an 8-byte header, which works out to
>>be about 1/8th of the slop that mainline kmalloc over SLAB has on
>
>
> Exactly. That overhead does not exist in SLUB. Thus SLOB is less efficient
> than SLUB.

What you trade for that is that one page page can only serve one slab.
For small systems, I would not be surprised if that was less space
efficient, even just looking at kmalloc caches in isolation. Or do you
have numbers to support your conclusion?

--
SUSE Labs, Novell Inc.
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