lkml.org 
[lkml]   [2012]   [Feb]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH v3 02/21] memcg: make mm_match_cgroup() hirarchical
    On Thu, Feb 23, 2012 at 05:51:46PM +0400, Konstantin Khlebnikov wrote:
    > Check mm-owner cgroup membership hierarchically.

    I think this one cat just beat up this other cat in front of my
    window, yelling something about money and missing product. Anyway, I
    already forgot why we want this patch. Could you describe that in the
    changelog, please?

    > @@ -821,6 +821,26 @@ struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p)
    > struct mem_cgroup, css);
    > }
    >
    > +/**
    > + * mm_match_cgroup - cgroup hierarchy mm membership test
    > + * @mm mm_struct to test
    > + * @cgroup target cgroup
    > + *
    > + * Returns true if mm belong this cgroup or any its child in hierarchy
    > + */
    > +int mm_match_cgroup(const struct mm_struct *mm, const struct mem_cgroup *cgroup)
    > +{
    > + struct mem_cgroup *memcg;
    > +
    > + rcu_read_lock();
    > + memcg = mem_cgroup_from_task(rcu_dereference((mm)->owner));
    > + while (memcg != cgroup && memcg && memcg->use_hierarchy)
    > + memcg = parent_mem_cgroup(memcg);
    > + rcu_read_unlock();
    > +
    > + return cgroup == memcg;
    > +}

    Please don't duplicate mem_cgroup_same_or_subtree()'s functionality in
    a worse way. The hierarchy information is kept in a stack such that
    ancestry can be detected in linear time, check out css_is_ancestor().

    If you don't want to nest rcu_read_lock(), you could push the
    rcu_read_lock() from css_is_ancestor() into its sole user and provide
    a __mem_cgroup_is_ancestor() that assumes rcu already read-locked.

    No?


    \
     
     \ /
      Last update: 2012-02-23 19:07    [W:0.024 / U:1.992 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site