* Johannes Weiner <hannes@xxxxxxxxxxx> [2011-02-03 15:26:01]: > This patch series removes the direct page pointer from struct > page_cgroup, which saves 20% of per-page memcg memory overhead (Fedora > and Ubuntu enable memcg per default, openSUSE apparently too). > > The node id or section number is encoded in the remaining free bits of > pc->flags which allows calculating the corresponding page without the > extra pointer. > > I ran, what I think is, a worst-case microbenchmark that just cats a > large sparse file to /dev/null, because it means that walking the LRU > list on behalf of per-cgroup reclaim and looking up pages from > page_cgroups is happening constantly and at a high rate. But it made > no measurable difference. A profile reported a 0.11% share of the new > lookup_cgroup_page() function in this benchmark. Wow! defintely worth a deeper look. > > Hannes -- 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 internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>