Messages in this thread Patch in this message | | | Date | Fri, 2 Apr 2010 20:33:09 +0200 | From | Oleg Nesterov <> | Subject | [PATCH -mm 4/4] oom: oom_forkbomb_penalty: move thread_group_cputime() out of task_lock() |
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It doesn't make sense to call thread_group_cputime() under task_lock(), we can drop this lock right after we read get_mm_rss() and save the value in the local variable.
Note: probably it makes more sense to use sum_exec_runtime instead of utime + stime, it is much more precise. A task can eat a lot of CPU time, but its Xtime can be zero.
Signed-off-by: Oleg Nesterov <oleg@redhat.com> ---
mm/oom_kill.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-)
--- MM/mm/oom_kill.c~4_FORKBOMB_DROP_TASK_LOCK_EARLIER 2010-04-02 19:55:46.000000000 +0200 +++ MM/mm/oom_kill.c 2010-04-02 20:16:13.000000000 +0200 @@ -110,13 +110,16 @@ static unsigned long oom_forkbomb_penalt return 0; list_for_each_entry(child, &tsk->children, sibling) { struct task_cputime task_time; - unsigned long runtime; + unsigned long runtime, rss; task_lock(child); if (!child->mm || child->mm == tsk->mm) { task_unlock(child); continue; } + rss = get_mm_rss(child->mm); + task_unlock(child); + thread_group_cputime(child, &task_time); runtime = cputime_to_jiffies(task_time.utime) + cputime_to_jiffies(task_time.stime); @@ -126,10 +129,9 @@ static unsigned long oom_forkbomb_penalt * get to execute at all in such cases anyway. */ if (runtime < HZ) { - child_rss += get_mm_rss(child->mm); + child_rss += rss; forkcount++; } - task_unlock(child); } /*
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