Re: [PATCH 08/40] mm: kmem_cache_objsize

[Peter Zijlstra]

On Fri, 2007-05-04 at 09:23 -0700, Christoph Lameter wrote:
> On Fri, 4 May 2007, Peter Zijlstra wrote:
> 
> > On Fri, 2007-05-04 at 09:09 -0700, Christoph Lameter wrote:
> > > On Fri, 4 May 2007, Pekka Enberg wrote:
> > > 
> > > > On 5/4/07, Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> wrote:
> > > > > Expost buffer_size in order to allow fair estimates on the actual space
> > > > > used/needed.
> > > 
> > > We already have ksize?
> > 
> > ksize gives the internal size, whereas these give the external size.
> > 
> > I need to know how much space I need to reserve, hence I need the
> > external size; whereas normally you want to know how much space you have
> > available, which is what ksize gives.
> > 
> > Didn't we have this discussion last time?
> 
> I was cced on that as far as I can tell.

Ah, that might have been, I was collecting Cc's but must've overlooked
you. My bad.

> The name objsize suggests the size of the object not the slab size.
> If you want this then maybe call it kmem_cache_slab_size. SLUB 
> distinguishes between obj_size which is the size of the struct that is 
> used and slab_size which is the size of the object after alignment, adding 
> debug information etc etc. See also slabinfo.c for a way to calculate 
> theses sizes from user space.

I'm open to renames, this is what Pekka suggested IIRC.

> If we really drop SLAB then we wont need this. SLUBs data structures are 
> not opaque.

Yeah, I know, I still have to add SLUB support, its high on my TODO list
though.

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