2014-12-16 5:42 GMT+03:00 Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>:
> On Mon, Dec 15, 2014 at 08:16:00AM -0600, Christoph Lameter wrote:
>> On Mon, 15 Dec 2014, Joonsoo Kim wrote:
>>
>> > > +static bool same_slab_page(struct kmem_cache *s, struct page *page, void *p)
>> > > +{
>> > > + long d = p - page->address;
>> > > +
>> > > + return d > 0 && d < (1 << MAX_ORDER) && d < (compound_order(page) << PAGE_SHIFT);
>> > > +}
>> > > +
>> >
>> > Somtimes, compound_order() induces one more cacheline access, because
>> > compound_order() access second struct page in order to get order. Is there
>> > any way to remove this?
>>
>> I already have code there to avoid the access if its within a MAX_ORDER
>> page. We could probably go for a smaller setting there. PAGE_COSTLY_ORDER?
>
> That is the solution to avoid compound_order() call when slab of
> object isn't matched with per cpu slab.
>
> What I'm asking is whether there is a way to avoid compound_order() call when slab
> of object is matched with per cpu slab or not.
>
Can we use page->objects for that?
Like this:
return d > 0 && d < page->objects * s->size;
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