On Tue, Dec 14, 2021 at 9:38 PM Johannes Weiner <hannes@xxxxxxxxxxx> wrote: > > On Tue, Dec 14, 2021 at 12:53:26AM +0800, Muchun Song wrote: > > The list_lru uses an array (list_lru_memcg->lru) to store pointers > > which point to the list_lru_one. And the array is per memcg per node. > > Therefore, the size of the arrays will be 10K * number_of_node * 8 ( > > a pointer size on 64 bits system) when we run 10k containers in the > > system. The memory consumption of the arrays becomes significant. The > > more numa node, the more memory it consumes. > > The complexity for the lists themselves is still nrmemcgs * nrnodes > right? But the rcu_head goes from that to nrmemcgs. Right. > > > I have done a simple test, which creates 10K memcg and mount point > > each in a two-node system. The memory consumption of the list_lru > > will be 24464MB. After converting the array from per memcg per node > > to per memcg, the memory consumption is going to be 21957MB. It is > > reduces by 2.5GB. In our AMD servers, there are 8 numa nodes in > > those system, the memory consumption could be more significant. > > The code looks good to me, but it would be useful to include a > high-level overview of the new scheme, explain that the savings come > from the rcu heads, that it simplifies the alloc/dealloc path etc. Will do in the next version. > > With that, > > > Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx> Thanks. > > Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
