* Johannes Weiner <hannes@xxxxxxxxxxx> [2011-01-17 20:14:00]: > Hello, > > on the MM summit, I would like to talk about the current state of > memory control groups, the features and extensions that are currently > being developed for it, and what their status is. > > I am especially interested in talking about the current runtime memory > overhead memcg comes with (1% of ram) and what we can do to shrink it. > > In comparison to how efficiently struct page is packed, and given that > distro kernels come with memcg enabled per default, I think we should > put a bit more thought into how struct page_cgroup (which exists for > every page in the system as well) is organized. > > I have a patch series that removes the page backpointer from struct > page_cgroup by storing a node ID (or section ID, depending on whether > sparsemem is configured) in the free bits of pc->flags. > > I also plan on replacing the pc->mem_cgroup pointer with an ID > (KAMEZAWA-san has patches for that), and move it to pc->flags too. > Every flag not used means doubling the amount of possible control > groups, so I have patches that get rid of some flags currently > allocated, including PCG_CACHE, PCG_ACCT_LRU, and PCG_MIGRATION. > > [ I meant to send those out much earlier already, but a bug in the > migration rework was not responding to my yelling 'Marco', and now my > changes collide horribly with THP, so it will take another rebase. ] > > The per-memcg dirty accounting work e.g. allocates a bunch of new bits > in pc->flags and I'd like to hash out if this leaves enough room for > the structure packing I described, or whether we can come up with a > different way of tracking state. > > Would other people be interested in discussing this? > I would definitely be if I am invited to the LSF/MM summit. Even otherwise we should discuss this over email -- Three Cheers, Balbir -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom policy in Canada: sign http://dissolvethecrtc.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>