lkml.org 
[lkml]   [2011]   [May]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    SubjectRe: [PATCH 3/5] oom: oom-killer don't use proportion of system-ram internally
    From
    2011/5/20 KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>:
    > CAI Qian reported his kernel did hang-up if he ran fork intensive
    > workload and then invoke oom-killer.
    >
    > The problem is, current oom calculation uses 0-1000 normalized value
    > (The unit is a permillage of system-ram). Its low precision make
    > a lot of same oom score. IOW, in his case, all processes have smaller
    > oom score than 1 and internal calculation round it to 1.
    >
    > Thus oom-killer kill ineligible process. This regression is caused by
    > commit a63d83f427 (oom: badness heuristic rewrite).
    >
    > The solution is, the internal calculation just use number of pages
    > instead of permillage of system-ram. And convert it to permillage
    > value at displaying time.
    >
    > This patch doesn't change any ABI (included  /proc/<pid>/oom_score_adj)
    > even though current logic has a lot of my dislike thing.
    >
    > Reported-by: CAI Qian <caiqian@redhat.com>
    > Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
    > ---
    >  fs/proc/base.c      |   13 ++++++----
    >  include/linux/oom.h |    7 +----
    >  mm/oom_kill.c       |   60 +++++++++++++++++++++++++++++++++-----------------
    >  3 files changed, 49 insertions(+), 31 deletions(-)
    >
    > diff --git a/fs/proc/base.c b/fs/proc/base.c
    > index dfa5327..d6b0424 100644
    > --- a/fs/proc/base.c
    > +++ b/fs/proc/base.c
    > @@ -476,14 +476,17 @@ static const struct file_operations proc_lstats_operations = {
    >
    >  static int proc_oom_score(struct task_struct *task, char *buffer)
    >  {
    > -       unsigned long points = 0;
    > +       unsigned long points;
    > +       unsigned long ratio = 0;
    > +       unsigned long totalpages = totalram_pages + total_swap_pages + 1;
    >
    >        read_lock(&tasklist_lock);
    > -       if (pid_alive(task))
    > -               points = oom_badness(task, NULL, NULL,
    > -                                       totalram_pages + total_swap_pages);
    > +       if (pid_alive(task)) {
    > +               points = oom_badness(task, NULL, NULL, totalpages);
    > +               ratio = points * 1000 / totalpages;
    > +       }
    >        read_unlock(&tasklist_lock);
    > -       return sprintf(buffer, "%lu\n", points);
    > +       return sprintf(buffer, "%lu\n", ratio);
    >  }
    >
    >  struct limit_names {
    > diff --git a/include/linux/oom.h b/include/linux/oom.h
    > index 5e3aa83..0f5b588 100644
    > --- a/include/linux/oom.h
    > +++ b/include/linux/oom.h
    > @@ -40,7 +40,8 @@ enum oom_constraint {
    >        CONSTRAINT_MEMCG,
    >  };
    >
    > -extern unsigned int oom_badness(struct task_struct *p, struct mem_cgroup *mem,
    > +/* The badness from the OOM killer */
    > +extern unsigned long oom_badness(struct task_struct *p, struct mem_cgroup *mem,
    >                        const nodemask_t *nodemask, unsigned long totalpages);
    >  extern int try_set_zonelist_oom(struct zonelist *zonelist, gfp_t gfp_flags);
    >  extern void clear_zonelist_oom(struct zonelist *zonelist, gfp_t gfp_flags);
    > @@ -62,10 +63,6 @@ static inline void oom_killer_enable(void)
    >        oom_killer_disabled = false;
    >  }
    >
    > -/* The badness from the OOM killer */
    > -extern unsigned long badness(struct task_struct *p, struct mem_cgroup *mem,
    > -                     const nodemask_t *nodemask, unsigned long uptime);
    > -
    >  extern struct task_struct *find_lock_task_mm(struct task_struct *p);
    >
    >  /* sysctls */
    > diff --git a/mm/oom_kill.c b/mm/oom_kill.c
    > index e6a6c6f..8bbc3df 100644
    > --- a/mm/oom_kill.c
    > +++ b/mm/oom_kill.c
    > @@ -132,10 +132,12 @@ static bool oom_unkillable_task(struct task_struct *p,
    >  * predictable as possible.  The goal is to return the highest value for the
    >  * task consuming the most memory to avoid subsequent oom failures.
    >  */
    > -unsigned int oom_badness(struct task_struct *p, struct mem_cgroup *mem,
    > +unsigned long oom_badness(struct task_struct *p, struct mem_cgroup *mem,
    >                      const nodemask_t *nodemask, unsigned long totalpages)
    >  {
    > -       int points;
    > +       unsigned long points;
    > +       unsigned long score_adj = 0;
    > +
    >
    >        if (oom_unkillable_task(p, mem, nodemask))
    >                return 0;
    > @@ -160,7 +162,7 @@ unsigned int oom_badness(struct task_struct *p, struct mem_cgroup *mem,
    >         */
    >        if (p->flags & PF_OOM_ORIGIN) {
    >                task_unlock(p);
    > -               return 1000;
    > +               return ULONG_MAX;
    >        }
    >
    >        /*
    > @@ -176,33 +178,49 @@ unsigned int oom_badness(struct task_struct *p, struct mem_cgroup *mem,
    >         */
    >        points = get_mm_rss(p->mm) + p->mm->nr_ptes;
    >        points += get_mm_counter(p->mm, MM_SWAPENTS);
    > -
    > -       points *= 1000;
    > -       points /= totalpages;
    >        task_unlock(p);
    >
    >        /*
    >         * Root processes get 3% bonus, just like the __vm_enough_memory()
    >         * implementation used by LSMs.
    > +        *
    > +        * XXX: Too large bonus, example, if the system have tera-bytes memory..
    >         */

    Nitpick. I have no opposition about adding this comment.
    But strictly speaking, the comment isn't related to this patch.
    No biggie and it's up to you. :)

    --
    Kind regards,
    Minchan Kim
    --
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2011-05-23 06:05    [W:0.034 / U:0.716 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site