RE: [PATCH] slub: remove a minus instruction in get_partial_node

[Christoph Lameter <cl@gentwo.org>]

On Sat, 8 Oct 2011, Alex,Shi wrote:

> On Mon, 2011-10-03 at 21:55 +0800, Christoph Lameter wrote:
> > On Sun, 2 Oct 2011, Shi, Alex wrote:
> >
> > > > A slab on the partial lists always has objects available. Why would it be
> > > > zero?
> > >
> > > Um, my mistaken. The reason should be: if code is here, the slab will be per cpu slab.
> > > It is no chance to be in per cpu partial and no relationship with per cpu partial. So
> > > no reason to use this value as a criteria for filling per cpu partial.
> >
> > I am not sure I understand you. The point of the code is to count the
> > objects available in the per cpu partial pages so that we can limit the
> > number of pages we fetch from the per node partial list.
>
> Maybe my understanding is incorrect for PCP. :)
> What I thought is: when object == null, the page we got from node
> partial list will be added into cpu slab. It has no chance to become per
> cpu partial page. And it has no relationship with further per cpu
> partial count checking. Since even 'available > cpu_partial/2', it
> doesn't mean per cpu partial objects number > cpu_partial/2.

acquire_slab should not return NULL unless something seriously goes wrong.
I think we can remove the]

	if (!t)

statement to avoid futher confusion?

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