On Wed, 9 Dec 2015, Jesper Dangaard Brouer wrote:
> I really like the idea of making it able to free kmalloc'ed objects.
> But I hate to change the API again... (I do have a use-case in the
> network stack where I could use this feature).
Now is the time to fix the API since its not that much in use yet if at
all.
> I'm traveling (to Sweden) Thursday (afternoon) and will be back late
> Friday (and have to play Viking in the weekend), thus to be realistic
> I'll start working on this Monday, so we can get some benchmark numbers
> to guide this decision.
Ok great.
> > - struct kmem_cache *s;
> > + struct page *page;
> >
> > - /* Support for memcg */
> > - s = cache_from_obj(orig_s, p[size - 1]);
> > + page = virt_to_head_page(p[size - 1]);
>
> Think we can drop this.
Well then you wont be able to check for a compound page. And you do not
want this check in build detached freelist.
>
> > - size = build_detached_freelist(s, size, p, &df);
> > + if (unlikely(!PageSlab(page))) {
> > + BUG_ON(!PageCompound(page));
> > + kfree_hook(p[size - 1]);
> > + __free_kmem_pages(page, compound_order(page));
> > + p[--size] = NULL;
> > + continue;
> > + }
>
> and move above into build_detached_freelist() and make it a little more
> pretty code wise (avoiding the p[size -1] juggling).
If we do this check here then we wont be needing it in
build_detached_freelist.
> > +
> > + size = build_detached_freelist(page->slab_cache, size, p, &df);
>
> also think we should be able to drop the kmem_cache param "page->slab_cache".
Yep.
>
>
> > if (unlikely(!df.page))
> > continue;
> >
> > - slab_free(s, df.page, df.freelist, df.tail, df.cnt, _RET_IP_);
> > + slab_free(page->slab_cache, df.page, df.freelist, df.tail, df.cnt, _RET_IP_);
Then we need df.slab_cache or something.
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