Re: Slab: Remove kmem_cache_t

[Nick Piggin <nickpiggin@yahoo.com.au>]

Linus Torvalds wrote:
> 
> On Thu, 30 Nov 2006, Nick Piggin wrote:
> 
>>>Because they are fundamentally _different_ on different architectures.
>>
>>So is struct kmem_cache for slab vs slob.
> 
> 
> No. It's always the same. Did you read the emails I send out?
> 
> I explicitly said that it doesn't matter if the _members_ change. That's 
> something else, and a typedef doesn't help at all.
> 
> A "struct kmem_cache" is always a "struct kmem_cache". I don't understand 
> why you're even arguing.
> 
> In contrast, a "pdt_t" can be "unsigned long" or an anonymous struct, or 
> anything else. A "u64" can be "unsigned long long" or "unsigned long" 
> depending on architecture, etc. But a "struct kmem_cache" is always a 
> "struct kmem_cache". 

Oh yeah, I was thinking you could put it in a struct anyway, but I get
your point about struct passing performance (even if it doesn't happen
much in the vm code).

> 
> There is ZERO advantage to a typedef here. And when there is zero 
> advantage, you shouldn't use a typedef because of the _negatives_ 
> associated with it that have been discussed.
> 
> So why use a typedef?

I guess I'm not arguing to use the typedef so much as I wanted to know why
it is being removed (ie. why now). Do you think that avoiding the slab.h
include when some code just needs a struct kmem_cache * is a good policy?

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