From: luca abeni <luca.abeni@santannapisa.it>
To: Juri Lelli <juri.lelli@redhat.com>
Cc: linux-kernel@vger.kernel.org,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"Rafael J . Wysocki" <rafael@kernel.org>,
Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Vincent Guittot <vincent.guittot@linaro.org>,
"Paul E . McKenney" <paulmck@linux.ibm.com>,
Joel Fernandes <joel@joelfernandes.org>,
Quentin Perret <quentin.perret@arm.com>,
Luc Van Oostenryck <luc.vanoostenryck@gmail.com>,
Morten Rasmussen <morten.rasmussen@arm.com>,
Daniel Bristot de Oliveira <bristot@redhat.com>,
Patrick Bellasi <patrick.bellasi@arm.com>,
Tommaso Cucinotta <tommaso.cucinotta@santannapisa.it>
Subject: Re: [RFC PATCH 2/6] sched/dl: Capacity-aware migrations
Date: Wed, 8 May 2019 10:17:57 +0200 [thread overview]
Message-ID: <20190508101757.1245ab84@nowhere> (raw)
In-Reply-To: <20190508080436.GF6551@localhost.localdomain>
On Wed, 8 May 2019 10:04:36 +0200
Juri Lelli <juri.lelli@redhat.com> wrote:
> Hi Luca,
>
> On 06/05/19 06:48, Luca Abeni wrote:
> > From: luca abeni <luca.abeni@santannapisa.it>
> >
> > Currently, the SCHED_DEADLINE scheduler uses a global EDF scheduling
> > algorithm, migrating tasks to CPU cores without considering the core
> > capacity and the task utilization. This works well on homogeneous
> > systems (SCHED_DEADLINE tasks are guaranteed to have a bounded
> > tardiness), but presents some issues on heterogeneous systems. For
> > example, a SCHED_DEADLINE task might be migrated on a core that has
> > not enough processing capacity to correctly serve the task (think
> > about a task with runtime 70ms and period 100ms migrated to a core
> > with processing capacity 0.5)
> >
> > This commit is a first step to address the issue: When a task wakes
> > up or migrates away from a CPU core, the scheduler tries to find an
> > idle core having enough processing capacity to serve the task.
> >
> > Signed-off-by: luca abeni <luca.abeni@santannapisa.it>
> > ---
> > kernel/sched/cpudeadline.c | 31 +++++++++++++++++++++++++++++--
> > kernel/sched/deadline.c | 8 ++++++--
> > kernel/sched/sched.h | 7 ++++++-
> > 3 files changed, 41 insertions(+), 5 deletions(-)
> >
> > diff --git a/kernel/sched/cpudeadline.c b/kernel/sched/cpudeadline.c
> > index 50316455ea66..d21f7905b9c1 100644
> > --- a/kernel/sched/cpudeadline.c
> > +++ b/kernel/sched/cpudeadline.c
> > @@ -110,6 +110,22 @@ static inline int cpudl_maximum(struct cpudl
> > *cp) return cp->elements[0].cpu;
> > }
> >
> > +static inline int dl_task_fit(const struct sched_dl_entity *dl_se,
> > + int cpu, u64 *c)
> > +{
> > + u64 cap = (arch_scale_cpu_capacity(NULL, cpu) *
> > arch_scale_freq_capacity(cpu)) >> SCHED_CAPACITY_SHIFT;
> > + s64 rel_deadline = dl_se->dl_deadline;
> > + u64 rem_runtime = dl_se->dl_runtime;
>
> This is not the dynamic remaining one, is it?
Right; I preferred to split this in two patches so that if we decide to
use only the static task parameters (dl_deadline and dl_runtime) I can
simply drop a patch ;-)
Luca
>
> I see however 4/6.. lemme better look at that.
>
> Best,
>
> - Juri
next prev parent reply other threads:[~2019-05-08 8:18 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-06 4:48 [RFC PATCH 0/6] Capacity awareness for SCHED_DEADLINE Luca Abeni
2019-05-06 4:48 ` [RFC PATCH 1/6] sched/dl: Improve deadline admission control for asymmetric CPU capacities Luca Abeni
2019-05-07 13:48 ` Quentin Perret
2019-05-07 13:55 ` Vincent Guittot
2019-05-07 14:02 ` Quentin Perret
2019-05-07 14:25 ` luca abeni
2019-05-07 14:31 ` Quentin Perret
2019-05-07 14:43 ` luca abeni
2019-07-08 11:22 ` Dietmar Eggemann
2019-07-08 15:05 ` Quentin Perret
2019-06-18 16:41 ` Alessio Balsini
2019-05-06 4:48 ` [RFC PATCH 2/6] sched/dl: Capacity-aware migrations Luca Abeni
2019-05-07 13:35 ` Quentin Perret
2019-05-07 14:17 ` luca abeni
2019-05-07 15:04 ` Quentin Perret
2019-05-07 14:10 ` Quentin Perret
2019-05-07 14:41 ` luca abeni
2019-05-07 15:02 ` Quentin Perret
2019-05-08 8:04 ` Juri Lelli
2019-05-08 8:17 ` luca abeni [this message]
2019-07-04 12:05 ` Dietmar Eggemann
2019-07-08 7:41 ` luca abeni
2019-07-08 10:41 ` Dietmar Eggemann
2019-05-06 4:48 ` [RFC PATCH 3/6] sched/dl: Try better placement even for deadline tasks that do not block Luca Abeni
2019-05-07 14:13 ` Quentin Perret
2019-05-07 16:00 ` Morten Rasmussen
2019-05-08 8:01 ` Juri Lelli
2019-05-08 8:14 ` luca abeni
2019-05-08 9:22 ` Juri Lelli
2019-07-08 13:55 ` Peter Zijlstra
2019-07-09 13:24 ` luca abeni
2019-07-09 13:42 ` Peter Zijlstra
2019-07-11 11:17 ` Dietmar Eggemann
2019-07-11 12:00 ` Peter Zijlstra
2019-07-11 15:33 ` Dietmar Eggemann
2019-07-09 14:44 ` Dietmar Eggemann
2019-05-06 4:48 ` [RFC PATCH 4/6] sched/dl: Improve capacity-aware wakeup Luca Abeni
2019-05-08 9:08 ` Juri Lelli
2019-05-08 9:24 ` luca abeni
2019-05-08 12:05 ` Juri Lelli
2019-05-08 12:47 ` luca abeni
2019-05-08 13:10 ` Juri Lelli
2019-05-08 14:12 ` luca abeni
2019-05-06 4:48 ` [RFC PATCH 5/6] sched/dl: If the task does not fit anywhere, select the fastest core Luca Abeni
2019-05-06 4:48 ` [RFC PATCH 6/6] sched/dl: Try not to select a too fast core Luca Abeni
2019-05-07 15:57 ` Quentin Perret
2019-05-08 6:26 ` luca abeni
2019-05-09 13:46 ` Quentin Perret
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