Messages in this thread Patch in this message | | | Subject | Re: [patch] Re: autogroup: sched_setscheduler() fails | From | Mike Galbraith <> | Date | Wed, 12 Jan 2011 06:40:42 +0100 |
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On Tue, 2011-01-11 at 19:48 +0100, Mike Galbraith wrote: > On Tue, 2011-01-11 at 22:40 +0530, Bharata B Rao wrote: > > On Mon, Jan 10, 2011 at 05:42:26PM +0100, Mike Galbraith wrote: > > > Index: linux-2.6/kernel/sched_autogroup.c > > > =================================================================== > > > --- linux-2.6.orig/kernel/sched_autogroup.c > > > +++ linux-2.6/kernel/sched_autogroup.c > > > @@ -73,6 +73,15 @@ static inline struct autogroup *autogrou > > > ag->id = atomic_inc_return(&autogroup_seq_nr); > > > ag->tg = tg; > > > tg->autogroup = ag; > > > +#ifdef CONFIG_RT_GROUP_SCHED > > > + /* > > > + * HACK: autogroup RT tasks run in the root task group. > > > + * This fools __sched_setscheduler() into proceeding on > > > + * so we can move the task to the appropriate runqueue > > > + * upon scheduling policy change. > > > + */ > > > + tg->rt_bandwidth.rt_runtime = RUNTIME_INF; > > > +#endif > > > > > > return ag; > > > > > > @@ -143,6 +152,15 @@ autogroup_move_group(struct task_struct > > > autogroup_kref_put(prev); > > > } > > > > > > +static inline void > > > +autogroup_setscheduler(struct task_struct *p, int on_rq) > > > +{ > > > + if (p->sched_class->task_move_group) > > > + p->sched_class->task_move_group(p, on_rq); > > > + else > > > + set_task_rq(p, task_cpu(p)); > > > +} > > > + > > > > IIUC, with the above changes you are actually queing the task into > > rt_rq of an autogroup. But the task's autogroup interface > > (/proc/<pid>/autogroup) allows you to control the bandwidth of only > > cfs_rq tasks, while the rt tasks in the group get RUNTIME_INF bandwidth. > > > > I think what we need is a real group change here (which is difficult I > > think) and not just sched_class change. > > Unless I fscked up, set_task_rq() is the group change. As soon as the > task's class changes, it'll be moved to the root_task_group.
But it'd be better to not touch anything, just deflect RT tasks away from useless queues from the start.
sched, autogroup: fix CONFIG_RT_GROUP_SCHED sched_setscheduler() failure.
If CONFIG_RT_GROUP_SCHED is set, sched_setscheduler() fails due to autogroup not allocating rt_runtime. Squirrel allocated but useless rt_se and rt_rq away for group destruction time, and deflect RT tasks to the root task group.
Signed-off-by: Mike Galbraith <efault@gmx.de> Reported-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
--- kernel/sched_autogroup.c | 13 +++++++++++++ kernel/sched_autogroup.h | 4 ++++ 2 files changed, 17 insertions(+)
Index: linux-2.6/kernel/sched_autogroup.c =================================================================== --- linux-2.6.orig/kernel/sched_autogroup.c +++ linux-2.6/kernel/sched_autogroup.c @@ -27,6 +27,11 @@ static inline void autogroup_destroy(str { struct autogroup *ag = container_of(kref, struct autogroup, kref); +#ifdef CONFIG_RT_GROUP_SCHED + ag->tg->rt_se = ag->rt_se; + ag->tg->rt_rq = ag->rt_rq; + ag->tg->rt_bandwidth.rt_runtime = 0; +#endif sched_destroy_group(ag->tg); } @@ -72,6 +77,14 @@ static inline struct autogroup *autogrou init_rwsem(&ag->lock); ag->id = atomic_inc_return(&autogroup_seq_nr); ag->tg = tg; +#ifdef CONFIG_RT_GROUP_SCHED + /* Sorry, we don't do RT, go away. */ + ag->rt_se = tg->rt_se; + ag->rt_rq = tg->rt_rq; + tg->rt_se = root_task_group.rt_se; + tg->rt_rq = root_task_group.rt_rq; + tg->rt_bandwidth.rt_runtime = root_task_group.rt_bandwidth.rt_runtime; +#endif tg->autogroup = ag; return ag; Index: linux-2.6/kernel/sched_autogroup.h =================================================================== --- linux-2.6.orig/kernel/sched_autogroup.h +++ linux-2.6/kernel/sched_autogroup.h @@ -6,6 +6,10 @@ struct autogroup { struct rw_semaphore lock; unsigned long id; int nice; +#ifdef CONFIG_RT_GROUP_SCHED + struct sched_rt_entity **rt_se; + struct rt_rq **rt_rq; +#endif }; static inline struct task_group *
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