On 08/20/2012 10:30 PM, Ying Han wrote: > Not exactly. Here reclaiming from root is mainly for "reclaiming from > root's exclusive lru", which links the page includes: > 1. processes running under root > 2. reparented pages from rmdir memcg under root > 3. bypassed pages > > Setting root cgroup's softlimit = 0 has the implication of putting > those pages to likely to reclaim, which works fine. The question is > that if no other memcg is above its softlimit, would it be a problem > to adding a bit extra pressure to root which always is eligible for > softlimit reclaim ( usage is always greater than softlimit). > > As an example, it works fine in our environment since we don't > explicitly put any process under root. Most of the pages linked in > root lru would be reparented pages which should be reclaimed prior to > others. Keep in mind that not all environments will be specialized to the point of having root memcg empty. This basically treats root memcg as a trash bin, and can be very detrimental to use cases where actual memory is present in there. It would maybe be better to have all this garbage to go to a separate place, like a shadow garbage memcg, which is invisible to the filesystem, and is always the first to be reclaimed from, in any circumstance. -- 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>