From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: Re: [PATCH v5 01/14] memcg: Make it possible to use the stock for more than one page. Date: Wed, 17 Oct 2012 15:11:55 -0700 Message-ID: <20121017151155.d417bd13.akpm@linux-foundation.org> References: <1350382611-20579-1-git-send-email-glommer@parallels.com> <1350382611-20579-2-git-send-email-glommer@parallels.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1350382611-20579-2-git-send-email-glommer-bzQdu9zFT3WakBO8gow8eQ@public.gmane.org> Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii" To: Glauber Costa Cc: linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Mel Gorman , Tejun Heo , Michal Hocko , Johannes Weiner , kamezawa.hiroyu-+CUm20s59erQFUHtdCDX3A@public.gmane.org, Christoph Lameter , David Rientjes , Pekka Enberg , devel-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Suleiman Souhlal On Tue, 16 Oct 2012 14:16:38 +0400 Glauber Costa wrote: > From: Suleiman Souhlal > > 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. spello. > */ > -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 memcg_stock_pcp.stock. > > ... >