Re: [PATCH] mm: create a separate slab for page->ptl allocation

From: Andrew Morton
Date: Tue Nov 05 2013 - 19:42:23 EST


On Wed, 6 Nov 2013 01:13:11 +0200 "Kirill A. Shutemov" <kirill@xxxxxxxxxxxxx> wrote:

> > Really the function shouldn't exist in this case. It is __init so the
> > sin is not terrible, but can this be arranged?
>
> I would like to get rid of __ptlock_alloc()/__ptlock_free() too, but I
> don't see a way within C: we need to know sizeof(spinlock_t) on
> preprocessor stage.
>
> We can have a hack on kbuild level: write small helper program to find out
> sizeof(spinlock_t) before start building and turn it into define.
> But it's overkill from my POV. And cross-compilation will be a fun.

Yes, it doesn't seem worth the fuss. The compiler will remove all this
code anyway, so for example ptlock_cache_init() becomes an empty function.
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