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    SubjectRe: [PATCH v4 3/5] memcg : stop scanning if enough
    On Mon 01-08-11 16:37:45, Michal Hocko wrote:
    > On Wed 27-07-11 14:49:00, KAMEZAWA Hiroyuki wrote:
    > > memcg :avoid node fallback scan if possible.
    > >
    > > Now, try_to_free_pages() scans all zonelist because the page allocator
    > > should visit all zonelists...but that behavior is harmful for memcg.
    > > Memcg just scans memory because it hits limit...no memory shortage
    > > in pased zonelist.
    > >
    > > For example, with following unbalanced nodes
    > >
    > > Node 0 Node 1
    > > File 1G 0
    > > Anon 200M 200M
    > >
    > > memcg will cause swap-out from Node1 at every vmscan.
    > >
    > > Another example, assume 1024 nodes system.
    > > With 1024 node system, memcg will visit 1024 nodes
    > > pages per vmscan... This is overkilling.
    > >
    > > This is why memcg's victim node selection logic doesn't work
    > > as expected.
    >
    > Previous patch adds nodemask filled by
    > mem_cgroup_select_victim_node. Shouldn't we rather limit that nodemask
    > to a victim node?

    Bahh, scratch that. I was jumping from one thing to another and got
    totally confused. Victim memcg is not bound to any particular node in
    general...
    Sorry for noise. I will try to get back to this tomorrow.

    --
    Michal Hocko
    SUSE Labs
    SUSE LINUX s.r.o.
    Lihovarska 1060/12
    190 00 Praha 9
    Czech Republic


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