On Tue 04-02-14 18:59:23, Vladimir Davydov wrote: > On 02/04/2014 06:52 PM, Michal Hocko wrote: > > On Sun 02-02-14 20:33:48, Vladimir Davydov wrote: > >> Suppose we are creating memcg cache A that could be merged with cache B > >> of the same memcg. Since any memcg cache has the same parameters as its > >> parent cache, parent caches PA and PB of memcg caches A and B must be > >> mergeable too. That means PA was merged with PB on creation or vice > >> versa, i.e. PA = PB. From that it follows that A = B, and we couldn't > >> even try to create cache B, because it already exists - a contradiction. > > I cannot tell I understand the above but I am totally not sure about the > > statement bellow. > > > >> So let's remove unused code responsible for merging memcg caches. > > How come the code was unused? find_mergeable called cache_match_memcg... > > Oh, sorry for misleading comment. I mean the code handling merging of > per-memcg caches is useless, AFAIU: if we find an alias for a per-memcg > cache on kmem_cache_create_memcg(), the parent of the found alias must > be the same as the parent_cache passed to kmem_cache_create_memcg(), but > if it were so, we would never proceed to the memcg cache creation, > because the cache we want to create already exists. I am still not sure I understand this correctly. So the outcome of this patch is that compatible caches of different memcgs can be merged together? Sorry if this is a stupid question but I am not that familiar with this area much I am just seeing that cache_match_memcg goes away and my understanding of the function is that it should prevent from different memcg's caches merging. -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>