Messages in this thread | | | Date | Wed, 8 Apr 2009 17:57:02 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH/RFC] do not count frozen tasks toward load |
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On Wed, 8 Apr 2009 19:45:12 -0500 Nathan Lynch <ntl@pobox.com> wrote:
> Freezing tasks via the cgroup freezer causes the load average to climb > because the freezer's current implementation puts frozen tasks in > uninterruptible sleep (D state). > > Some applications which perform job-scheduling functions consult the > load average when making decisions. If a cgroup is frozen, the load > average does not provide a useful measure of the system's utilization > to such applications. This is especially inconvenient if the job > scheduler employs the cgroup freezer as a mechanism for preempting low > priority jobs. Contrast this with using SIGSTOP for the same purpose: > the stopped tasks do not count toward system load. > > Change task_contributes_to_load() to return false if the task is > frozen. This results in /proc/loadavg behavior that better meets > users' expectations. > > Signed-off-by: Nathan Lynch <ntl@pobox.com> > --- > include/linux/sched.h | 3 ++- > 1 files changed, 2 insertions(+), 1 deletions(-) > > diff --git a/include/linux/sched.h b/include/linux/sched.h > index 011db2f..f8af167 100644 > --- a/include/linux/sched.h > +++ b/include/linux/sched.h > @@ -202,7 +202,8 @@ extern unsigned long long time_sync_thresh; > #define task_is_stopped_or_traced(task) \ > ((task->state & (__TASK_STOPPED | __TASK_TRACED)) != 0) > #define task_contributes_to_load(task) \ > - ((task->state & TASK_UNINTERRUPTIBLE) != 0) > + ((task->state & TASK_UNINTERRUPTIBLE) != 0 && \ > + (task->flags & PF_FROZEN) == 0) > > #define __set_task_state(tsk, state_value) \ > do { (tsk)->state = (state_value); } while (0)
Looks OK to me. It should perhaps use !frozen(task), but the includes are mucked up.
I suppose we should fix this in -stable too.
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