lkml.org 
[lkml]   [2010]   [May]   [31]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [RFC] oom-kill: give the dying task a higher priority
    On Mon, 31 May 2010 15:09:41 +0900
    Minchan Kim <minchan.kim@gmail.com> wrote:

    > On Mon, May 31, 2010 at 2:54 PM, KAMEZAWA Hiroyuki
    > <kamezawa.hiroyu@jp.fujitsu.com> wrote:
    > > On Mon, 31 May 2010 14:46:05 +0900
    > > Minchan Kim <minchan.kim@gmail.com> wrote:
    > >
    > >> On Mon, May 31, 2010 at 2:04 PM, KAMEZAWA Hiroyuki
    > >> <kamezawa.hiroyu@jp.fujitsu.com> wrote:
    > >> > On Mon, 31 May 2010 14:01:03 +0900
    > >> > Minchan Kim <minchan.kim@gmail.com> wrote:
    > >> >
    > >> >> Hi, Kame.
    > >> >>
    > >> >> On Mon, May 31, 2010 at 9:21 AM, KAMEZAWA Hiroyuki
    > >> >> <kamezawa.hiroyu@jp.fujitsu.com> wrote:
    > >> >> > On Fri, 28 May 2010 13:48:26 -0300
    > >> >> > "Luis Claudio R. Goncalves" <lclaudio@uudg.org> wrote:
    > >> >> >>
    > >> >> >> oom-killer: give the dying task rt priority (v3)
    > >> >> >>
    > >> >> >> Give the dying task RT priority so that it can be scheduled quickly and die,
    > >> >> >> freeing needed memory.
    > >> >> >>
    > >> >> >> Signed-off-by: Luis Claudio R. Gonçalves <lgoncalv@redhat.com>
    > >> >> >>
    > >> >> >> diff --git a/mm/oom_kill.c b/mm/oom_kill.c
    > >> >> >> index 84bbba2..2b0204f 100644
    > >> >> >> --- a/mm/oom_kill.c
    > >> >> >> +++ b/mm/oom_kill.c
    > >> >> >> @@ -266,6 +266,8 @@ static struct task_struct *select_bad_process(unsigned long *ppoints)
    > >> >> >>   */
    > >> >> >>  static void __oom_kill_task(struct task_struct *p, int verbose)
    > >> >> >>  {
    > >> >> >> +     struct sched_param param;
    > >> >> >> +
    > >> >> >>       if (is_global_init(p)) {
    > >> >> >>               WARN_ON(1);
    > >> >> >>               printk(KERN_WARNING "tried to kill init!\n");
    > >> >> >> @@ -288,6 +290,8 @@ static void __oom_kill_task(struct task_struct *p, int verbose)
    > >> >> >>        * exit() and clear out its resources quickly...
    > >> >> >>        */
    > >> >> >>       p->time_slice = HZ;
    > >> >> >> +     param.sched_priority = MAX_RT_PRIO-10;
    > >> >> >> +     sched_setscheduler(p, SCHED_FIFO, &param);
    > >> >> >>       set_tsk_thread_flag(p, TIF_MEMDIE);
    > >> >> >>
    > >> >> >
    > >> >> > BTW, how about the other threads which share mm_struct ?
    > >> >>
    > >> >> Could you elaborate your intention? :)
    > >> >>
    > >> >
    > >> > IIUC, the purpose of rising priority is to accerate dying thread to exit()
    > >> > for freeing memory AFAP. But to free memory, exit, all threads which share
    > >> > mm_struct should exit, too. I'm sorry if I miss something.
    > >>
    > >> How do we kill only some thread and what's the benefit of it?
    > >> I think when if some thread receives  KILL signal, the process include
    > >> the thread will be killed.
    > >>
    > > yes, so, if you want a _process_ die quickly, you have to acceralte the whole
    > > threads on a process. Acceralating a thread in a process is not big help.
    >
    > Yes.
    >
    > I see the code.
    > oom_kill_process is called by
    >
    > 1. mem_cgroup_out_of_memory
    > 2. __out_of_memory
    > 3. out_of_memory
    >
    >
    > (1,2) calls select_bad_process which select victim task in processes
    > by do_each_process.
    > But 3 isn't In case of CONSTRAINT_MEMORY_POLICY, it kills current.
    > In only the case, couldn't we pass task of process, not one of thread?
    >

    Hmm, my point is that priority-acceralation is against a thread, not against a process.
    So, most of threads in memory-eater will not gain high priority even with this patch
    and works slowly.
    I have no objections to this patch. I just want to confirm the purpose. If this patch
    is for accelating exiting process by SIGKILL, it seems not enough.
    If an explanation as "acceralating all thread's priority in a process seems overkill"
    is given in changelog or comment, it's ok to me.

    Thanks,
    -Kame

    --
    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: 2010-05-31 08:57    [W:0.032 / U:0.328 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site