Re: [PATCH v5 01/14] memcg: Make it possible to use the stock formore than one page.
From: Andrew Morton
Date: Wed Oct 17 2012 - 18:11:46 EST
On Tue, 16 Oct 2012 14:16:38 +0400
Glauber Costa <glommer@xxxxxxxxxxxxx> wrote:
> From: Suleiman Souhlal <ssouhlal@xxxxxxxxxxx>
> We currently have a percpu stock cache scheme that charges one page at a
> time from memcg->res, the user counter. When the kernel memory
> controller comes into play, we'll need to charge more than that.
> This is because kernel memory allocations will also draw from the user
> counter, and can be bigger than a single page, as it is the case with
> the stack (usually 2 pages) or some higher order slabs.
> - * Try to consume stocked charge on this cpu. If success, one page is consumed
> - * from local stock and true is returned. If the stock is 0 or charges from a
> - * cgroup which is not current target, returns false. This stock will be
> - * refilled.
> + * consume_stock: Try to consume stocked charge on this cpu.
> + * @memcg: memcg to consume from.
> + * @nr_pages: how many pages to charge.
> + *
> + * The charges will only happen if @memcg matches the current cpu's memcg
> + * stock, and at least @nr_pages are available in that stock. Failure to
> + * service an allocation will refill the stock.
> + *
> + * returns true if succesfull, false otherwise.
> -static bool consume_stock(struct mem_cgroup *memcg)
> +static bool consume_stock(struct mem_cgroup *memcg, int nr_pages)
I don't believe there is a case for nr_pages < 0 here? If not then I
suggest that it would be clearer to use an unsigned type, like
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