• KAMEZAWA Hiroyuki's avatar
    tracepoint: add tracepoints for debugging oom_score_adj · 43d2b113
    KAMEZAWA Hiroyuki authored
    oom_score_adj is used for guarding processes from OOM-Killer.  One of
    problem is that it's inherited at fork().  When a daemon set oom_score_adj
    and make children, it's hard to know where the value is set.
    
    This patch adds some tracepoints useful for debugging. This patch adds
    3 trace points.
      - creating new task
      - renaming a task (exec)
      - set oom_score_adj
    
    To debug, users need to enable some trace pointer. Maybe filtering is useful as
    
    # EVENT=/sys/kernel/debug/tracing/events/task/
    # echo "oom_score_adj != 0" > $EVENT/task_newtask/filter
    # echo "oom_score_adj != 0" > $EVENT/task_rename/filter
    # echo 1 > $EVENT/enable
    # EVENT=/sys/kernel/debug/tracing/events/oom/
    # echo 1 > $EVENT/enable
    
    output will be like this.
    # grep oom /sys/kernel/debug/tracing/trace
    bash-7699  [007] d..3  5140.744510: oom_score_adj_update: pid=7699 comm=bash oom_score_adj=-1000
    bash-7699  [007] ...1  5151.818022: task_newtask: pid=7729 comm=bash clone_flags=1200011 oom_score_adj=-1000
    ls-7729  [003] ...2  5151.818504: task_rename: pid=7729 oldcomm=bash newcomm=ls oom_score_adj=-1000
    bash-7699  [002] ...1  5175.701468: task_newtask: pid=7730 comm=bash clone_flags=1200011 oom_score_adj=-1000
    grep-7730  [007] ...2  5175.701993: task_rename: pid=7730 oldcomm=bash newcomm=grep oom_score_adj=-1000
    Signed-off-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
    Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
    Acked-by: default avatarDavid Rientjes <rientjes@google.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    43d2b113
task.h 1.44 KB