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    SubjectRe: [RFC] Shared page accounting for memory cgroup
    * KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> [2010-01-06 16:12:11]:

    > On Wed, 6 Jan 2010 12:31:50 +0530
    > Balbir Singh <balbir@linux.vnet.ibm.com> wrote:
    > > > No. If it takes long time, locking fork()/exit() for such long time is the bigger
    > > > issue.
    > > > I recommend you to add memacct subsystem to sum up RSS of all processes's RSS counting
    > > > under a cgroup. Althoght it may add huge costs in page fault path but implementation
    > > > will be very simple and will not hurt realtime ops.
    > > > There will be no terrible race, I guess.
    > > >
    > >
    > > But others hold that lock as well, simple thing like listing tasks and
    > > moving tasks, etc. I expect the usage of shared to be in the same
    > > range.
    > >
    >
    > And piles up costs ? I think cgroup guys should pay attention to fork/exit
    > costs more. Now, it gets slower and slower.
    > In that point, I never like migrate-at-task-move work in cpuset and memcg.
    >
    > My 1st objection to this patch is this "shared" doesn't mean "shared between
    > cgroup" but means "shared between processes".
    > I think it's of no use and no help to users.
    >

    So what in your opinion would help end users? My concern is that as
    we make progress with memcg, we account only for privately used pages
    with no hint/data about the real usage (shared within or with other
    cgroups). How do we decide if one cgroup is really heavy?

    > And implementation is 2nd thing.
    >

    More details on your concern, please!

    --
    Balbir


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