4.12-rc ppc64 4k-page needs costly allocations

[Michael Ellerman]

Christoph Lameter <cl at linux.com> writes:

> On Thu, 1 Jun 2017, Hugh Dickins wrote:
>
>> Thanks a lot for working that out.  Makes sense, fully understood now,
>> nothing to worry about (though makes one wonder whether it's efficient
>> to use ctors on high-alignment caches; or whether an internal "zero-me"
>> ctor would be useful).
>
> Use kzalloc to zero it.

But that's changing a per slab creation memset into a per object
allocation memset, isn't it?

> And here is another example of using slab allocations for page frames.
> Use the page allocator for this? The page allocator is there for
> allocating page frames. The slab allocator main purpose is to allocate
> small objects....

Well usually they are small (< PAGE_SIZE), because we have 64K pages.

But we could rework the code to use the page allocator on 4K configs.

cheers