On Wed, Aug 1, 2012 at 1:45 AM, Michal Hocko <mhocko@xxxxxxx> wrote: > On Tue 31-07-12 13:59:35, Ying Han wrote: > [...] >> Let's say the following example where the cgroup is sorted by css_id, >> and none of the cgroup's usage is above softlimit (except root) >> >> root a b c d e f ...max >> thread_1 (priority = 12) ^ >> iter->position = 1 ( >> over_softlimit = true ) >> >> ^ >> iter->position = 2 >> >> thread_2 (priority = 12) ^ >> iter->position = 3 >> >> .... >> ^ >> >> iter->position = 0 ( over_softlimit = false ) >> >> In this case, thread 1 gets root but not thread 2 since they share the >> walk under same zone (same node) and same reclaim priority. > > That is true iterator is per zone per priority if the cookie is used but > that wasn't my point. > Take a much simpler case. Just the background reclaim without any direct > reclaim. Then there is nobody to race with and so we would always visit > the whole tree including the root and so if no group is above the soft > limit we would hammer the root cgroup until priority gets down when we > ignore the limit and reclaim from all. Makes sense? That is true. Hmm, then two things i can do: 1. for kswapd case, make sure not counting the root cgroup 2. or check nr_scanned. I like the nr_scanned which is telling us whether or not the reclaim ever make any attempt ? --Ying > -- > 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>