From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michal Hocko Subject: Re: [PATCH 1/2] gfp: add __GFP_NOACCOUNT Date: Wed, 6 May 2015 15:46:20 +0200 Message-ID: <20150506134620.GM14550@dhcp22.suse.cz> References: <20150506115941.GH14550@dhcp22.suse.cz> <20150506131622.GA4629@cmpxchg.org> Mime-Version: 1.0 Return-path: Content-Disposition: inline In-Reply-To: <20150506131622.GA4629-druUgvl0LCNAfugRpC6u6w@public.gmane.org> Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Johannes Weiner Cc: Vladimir Davydov , Andrew Morton , Tejun Heo , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Greg Thelen , linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org On Wed 06-05-15 09:16:22, Johannes Weiner wrote: > On Wed, May 06, 2015 at 01:59:41PM +0200, Michal Hocko wrote: > > On Tue 05-05-15 12:45:42, Vladimir Davydov wrote: > > > Not all kmem allocations should be accounted to memcg. The following > > > patch gives an example when accounting of a certain type of allocations > > > to memcg can effectively result in a memory leak. > > > > > This patch adds the __GFP_NOACCOUNT flag which if passed to kmalloc > > > and friends will force the allocation to go through the root > > > cgroup. It will be used by the next patch. > > > > The name of the flag is way too generic. It is not clear that the > > accounting is KMEMCG related. > > The memory controller is the (primary) component that accounts > physical memory allocations in the kernel, so I don't see how this > would be ambiguous in any way. What if a high-level allocator wants to do some accounting as well? E.g. slab allocator accounts {un}reclaimable pages. It is a different thing because the accounting is per-cache rather than gfp based but I just wanted to point out that accounting is rather a wide term. > > __GFP_NO_KMEMCG sounds better? > > I think that's much worse. I would prefer communicating the desired > behavior directly instead of having to derive it from a subsystem > name. > (And KMEMCG should not even be a term, it's all just the memory > controller, i.e. memcg.) I do not mind __GFP_NO_MEMCG either. -- Michal Hocko SUSE Labs