On Tue, 2016-11-22 at 16:59 +0100, Michael Kerrisk (man-pages) wrote:
> ┌─────────────────────────────────────────────────────┐
> │FIXME │
> ├─────────────────────────────────────────────────────┤
> │Regarding the previous paragraph... My tests indi‐ │
> │cate that writing *any* value to the autogroup file │
> │causes the task group to get a lower priority. This │
Because autogroup didn't call the then meaningless scale_load()...
Autogroup nice level adjustment has been broken ever since load
resolution was increased for 64bit kernels. Use scale_load() to
scale group weight.
Signed-off-by: Mike Galbraith <umgwanakikbuti@xxxxxxxxx>
Reported-by: Michael Kerrisk <mtk.manpages@xxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
---
kernel/sched/auto_group.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
--- a/kernel/sched/auto_group.c
+++ b/kernel/sched/auto_group.c
@@ -192,6 +192,7 @@ int proc_sched_autogroup_set_nice(struct
{
static unsigned long next = INITIAL_JIFFIES;
struct autogroup *ag;
+ unsigned long shares;
int err;
if (nice < MIN_NICE || nice > MAX_NICE)
@@ -210,9 +211,10 @@ int proc_sched_autogroup_set_nice(struct
next = HZ / 10 + jiffies;
ag = autogroup_task_get(p);
+ shares = scale_load(sched_prio_to_weight[nice + 20]);
down_write(&ag->lock);
- err = sched_group_set_shares(ag->tg, sched_prio_to_weight[nice + 20]);
+ err = sched_group_set_shares(ag->tg, shares);
if (!err)
ag->nice = nice;
up_write(&ag->lock);
--
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