On Wed, 20 Oct 2010 11:24:31 +0900 KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> wrote: > On Wed, 20 Oct 2010 10:14:21 +0900 > KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> wrote: > > > On Wed, 20 Oct 2010 09:48:21 +0900 > > Daisuke Nishimura <nishimura@xxxxxxxxxxxxxxxxx> wrote: > > > > > On Wed, 20 Oct 2010 09:11:09 +0900 > > > KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> wrote: > > > > > > > On Tue, 19 Oct 2010 14:00:58 -0700 > > > > Greg Thelen <gthelen@xxxxxxxxxx> wrote: > > > > > > > (snip) > > > > > +When use_hierarchy=0, each cgroup has independent dirty memory usage and limits. > > > > > + > > > > > +When use_hierarchy=1, a parent cgroup increasing its dirty memory usage will > > > > > +compare its total_dirty memory (which includes sum of all child cgroup dirty > > > > > +memory) to its dirty limits. This keeps a parent from explicitly exceeding its > > > > > +dirty limits. However, a child cgroup can increase its dirty usage without > > > > > +considering the parent's dirty limits. Thus the parent's total_dirty can exceed > > > > > +the parent's dirty limits as a child dirties pages. > > > > > > > > Hmm. in short, dirty_ratio in use_hierarchy=1 doesn't work as an user expects. > > > > Is this a spec. or a current implementation ? > > > > > > > > I think as following. > > > > - add a limitation as "At setting chidlren's dirty_ratio, it must be below parent's. > > > > If it exceeds parent's dirty_ratio, EINVAL is returned." > > > > > > > > Could you modify setting memory.dirty_ratio code ? > > > > Then, parent's dirty_ratio will never exceeds its own. (If I understand correctly.) > > > > > > > > "memory.dirty_limit_in_bytes" will be a bit more complecated, but I think you can. > > > > > > > I agree. > > > > > > At the first impression, this limitation seems a bit overkill for me, because > > > we allow memory.limit_in_bytes of a child bigger than that of parent now. > > > But considering more, the situation is different, because usage_in_bytes never > > > exceeds limit_in_bytes. > > > > > > > I'd like to consider a patch. > > Please mention that "use_hierarchy=1 case depends on implemenation." for now. > > > > BTW, how about supporing dirty_limit_in_bytes when use_hierarchy=0 or leave it as > broken when use_hierarchy=1 ? > It seems we can only support dirty_ratio when hierarchy is used. > It's all right for me. This feature would be useful even w/o hierarchy support. Thanks, Daisuke Nishimura. -- 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/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>