On Mon 03-11-14 10:09:42, Johannes Weiner wrote: > Hi Joonsoo, > > On Mon, Nov 03, 2014 at 05:02:08PM +0900, Joonsoo Kim wrote: > > On Sat, Nov 01, 2014 at 11:15:54PM -0400, Johannes Weiner wrote: > > > Memory cgroups used to have 5 per-page pointers. To allow users to > > > disable that amount of overhead during runtime, those pointers were > > > allocated in a separate array, with a translation layer between them > > > and struct page. > > > > Hello, Johannes. > > > > I'd like to leave this translation layer. > > Could you just disable that code with #ifdef until next user comes? > > > > In our company, we uses PAGE_OWNER on mm tree which is the feature > > saying who allocates the page. To use PAGE_OWNER needs modifying > > struct page and then needs re-compile. This re-compile makes us difficult > > to use this feature. So, we decide to implement run-time configurable > > PAGE_OWNER through page_cgroup's translation layer code. Moreover, with > > this infrastructure, I plan to implement some other debugging feature. > > > > Because of my laziness, it didn't submitted to LKML. But, I will > > submit it as soon as possible. If the code is removed, I would > > copy-and-paste the code, but, it would cause lose of the history on > > that code. So if possible, I'd like to leave that code now. > > Please re-introduce this code when your new usecase is ready to be > upstreamed. There is little reason to burden an unrelated feature > with a sizable chunk of dead code for a vague future user.
Completely agreed! I would hate to have some random feature piggy back on memcg internal structures. For that to be acceptable the page_cgroup would have to be abstracted into a more generic structure which wouldn't be under CONFIG_MEMCG anyway. -- Michal Hocko SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
