From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx106.postini.com [74.125.245.106]) by kanga.kvack.org (Postfix) with SMTP id 649DB6B005D for ; Wed, 15 Aug 2012 09:51:51 -0400 (EDT) Message-ID: <502BA96C.8070602@parallels.com> Date: Wed, 15 Aug 2012 17:51:40 +0400 From: Glauber Costa MIME-Version: 1.0 Subject: Re: [PATCH v2 07/11] mm: Allocate kernel pages to the right memcg References: <1344517279-30646-1-git-send-email-glommer@parallels.com> <1344517279-30646-8-git-send-email-glommer@parallels.com> <20120814151616.GO4177@suse.de> <502B66F8.30909@parallels.com> <20120815132244.GQ4177@suse.de> In-Reply-To: <20120815132244.GQ4177@suse.de> Content-Type: text/plain; charset="ISO-8859-15" Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Mel Gorman Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, cgroups@vger.kernel.org, devel@openvz.org, Michal Hocko , Johannes Weiner , Andrew Morton , kamezawa.hiroyu@jp.fujitsu.com, Christoph Lameter , David Rientjes , Pekka Enberg , Pekka Enberg , Suleiman Souhlal On 08/15/2012 05:22 PM, Mel Gorman wrote: >> I believe it >> > to be a better and less complicated approach then letting a page appear >> > and then charging it. Besides being consistent with the rest of memcg, >> > it won't create unnecessary disturbance in the page allocator >> > when the allocation is to fail. >> > > I still don't get why you did not just return a mem_cgroup instead of a > handle. > Forgot this one, sorry: The reason is to keep the semantics simple. What should we return if the code is not compiled in? If we return NULL for failure, the test becomes memcg = memcg_kmem_charge_page(gfp, order); if (!memcg) exit; If we're not compiled in, we'd either return positive garbage or we need to wrap it inside an ifdef I personally believe to be a lot more clear to standardize on true to mean "allocation can proceed". the compiled out case becomes: if (!true) exit; which is easily compiled away altogether. Now of course, using struct mem_cgroup makes sense, and I have already changed that here. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org