Re: [PATCH v2 3/5] slab: restrict the number of objects in a slab

[Christoph Lameter <cl@linux.com>]

On Sat, 19 Oct 2013, JoonSoo Kim wrote:

> > Ok so that results in a mininum size object size of 2^(12 - 8) = 2^4 ==
> > 16 bytes on x86. This is not true for order 1 pages (which SLAB also
> > supports) where we need 32 bytes.
>
> According to current slab size calculating logic, slab whose object size is
> less or equal to 16 bytes use only order 0 page. So there is no problem.

Ok then lets add a VM_BUG_ON to detect the situation when someone tries
something different.

> > Problems may arise on PPC or IA64 where the page size may be larger than
> > 64K. With 64K we have a mininum size of 2^(16 - 8) = 256 bytes. For those
> > arches we may need 16 bit sized indexes. Maybe make that compile time
> > determined base on page size? > 64KByte results in 16 bit sized indexes?
>
> Okay. I will try it.

Again compile time. You had runtime in some earlier patches which adds new
branches to key functions.

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