Re: + fix-spellings-of-slab-allocator-section-in-init-kconfig.patchadded to -mm tree

[Nick Piggin]

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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