From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Galbraith Subject: [patch] sched/autogroup: Fix 64bit kernel nice adjustment Date: Wed, 23 Nov 2016 11:33:37 +0100 Message-ID: <1479897217.4306.6.camel@gmx.de> References: <41d802dc-873a-ff02-17ff-93ce50f3e925@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-2022-jp" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <41d802dc-873a-ff02-17ff-93ce50f3e925@gmail.com> Sender: linux-kernel-owner@vger.kernel.org To: "Michael Kerrisk (man-pages)" Cc: Peter Zijlstra , Ingo Molnar , linux-man , lkml , Thomas Gleixner List-Id: linux-man@vger.kernel.org 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 Reported-by: Michael Kerrisk Cc: stable@vger.kernel.org --- 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);