From: mark gross <mgross@linux.intel.com>
To: Vineeth Remanan Pillai <vpillai@digitalocean.com>
Cc: Nishanth Aravamudan <naravamudan@digitalocean.com>,
Julien Desfossez <jdesfossez@digitalocean.com>,
Peter Zijlstra <peterz@infradead.org>,
Tim Chen <tim.c.chen@linux.intel.com>,
mingo@kernel.org, tglx@linutronix.de, pjt@google.com,
torvalds@linux-foundation.org, linux-kernel@vger.kernel.org,
subhra.mazumdar@oracle.com, fweisbec@gmail.com,
keescook@chromium.org, kerrnel@google.com,
Phil Auld <pauld@redhat.com>, Aaron Lu <aaron.lwe@gmail.com>,
Aubrey Li <aubrey.intel@gmail.com>,
Valentin Schneider <valentin.schneider@arm.com>,
Mel Gorman <mgorman@techsingularity.net>,
Pawan Gupta <pawan.kumar.gupta@linux.intel.com>,
Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: [RFC PATCH v3 07/16] sched: Allow put_prev_task() to drop rq->lock
Date: Mon, 26 Aug 2019 09:51:47 -0700 [thread overview]
Message-ID: <20190826165147.GE2680@u1904> (raw)
In-Reply-To: <e4519f6850477ab7f3d257062796e6425ee4ba7c.1559129225.git.vpillai@digitalocean.com>
On Wed, May 29, 2019 at 08:36:43PM +0000, Vineeth Remanan Pillai wrote:
> From: Peter Zijlstra <peterz@infradead.org>
>
> Currently the pick_next_task() loop is convoluted and ugly because of
> how it can drop the rq->lock and needs to restart the picking.
>
> For the RT/Deadline classes, it is put_prev_task() where we do
> balancing, and we could do this before the picking loop. Make this
> possible.
Maybe explain why adding strtu rq_flags pointers to the function call supports
the above commit coment.
--mark
>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> ---
> kernel/sched/core.c | 2 +-
> kernel/sched/deadline.c | 14 +++++++++++++-
> kernel/sched/fair.c | 2 +-
> kernel/sched/idle.c | 2 +-
> kernel/sched/rt.c | 14 +++++++++++++-
> kernel/sched/sched.h | 4 ++--
> kernel/sched/stop_task.c | 2 +-
> 7 files changed, 32 insertions(+), 8 deletions(-)
>
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index 32ea79fb8d29..9dfa0c53deb3 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -5595,7 +5595,7 @@ static void calc_load_migrate(struct rq *rq)
> atomic_long_add(delta, &calc_load_tasks);
> }
>
> -static void put_prev_task_fake(struct rq *rq, struct task_struct *prev)
> +static void put_prev_task_fake(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
> {
> }
>
> diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
> index c02b3229e2c3..45425f971eec 100644
> --- a/kernel/sched/deadline.c
> +++ b/kernel/sched/deadline.c
> @@ -1772,13 +1772,25 @@ pick_next_task_dl(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
> return p;
> }
>
> -static void put_prev_task_dl(struct rq *rq, struct task_struct *p)
> +static void put_prev_task_dl(struct rq *rq, struct task_struct *p, struct rq_flags *rf)
> {
> update_curr_dl(rq);
>
> update_dl_rq_load_avg(rq_clock_pelt(rq), rq, 1);
> if (on_dl_rq(&p->dl) && p->nr_cpus_allowed > 1)
> enqueue_pushable_dl_task(rq, p);
> +
> + if (rf && !on_dl_rq(&p->dl) && need_pull_dl_task(rq, p)) {
> + /*
> + * This is OK, because current is on_cpu, which avoids it being
> + * picked for load-balance and preemption/IRQs are still
> + * disabled avoiding further scheduler activity on it and we've
> + * not yet started the picking loop.
> + */
> + rq_unpin_lock(rq, rf);
> + pull_dl_task(rq);
> + rq_repin_lock(rq, rf);
> + }
> }
>
> /*
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 49707b4797de..8e3eb243fd9f 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -7110,7 +7110,7 @@ done: __maybe_unused;
> /*
> * Account for a descheduled task:
> */
> -static void put_prev_task_fair(struct rq *rq, struct task_struct *prev)
> +static void put_prev_task_fair(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
> {
> struct sched_entity *se = &prev->se;
> struct cfs_rq *cfs_rq;
> diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c
> index dd64be34881d..1b65a4c3683e 100644
> --- a/kernel/sched/idle.c
> +++ b/kernel/sched/idle.c
> @@ -373,7 +373,7 @@ static void check_preempt_curr_idle(struct rq *rq, struct task_struct *p, int fl
> resched_curr(rq);
> }
>
> -static void put_prev_task_idle(struct rq *rq, struct task_struct *prev)
> +static void put_prev_task_idle(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
> {
> }
>
> diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
> index adec98a94f2b..51ee87c5a28a 100644
> --- a/kernel/sched/rt.c
> +++ b/kernel/sched/rt.c
> @@ -1593,7 +1593,7 @@ pick_next_task_rt(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
> return p;
> }
>
> -static void put_prev_task_rt(struct rq *rq, struct task_struct *p)
> +static void put_prev_task_rt(struct rq *rq, struct task_struct *p, struct rq_flags *rf)
> {
> update_curr_rt(rq);
>
> @@ -1605,6 +1605,18 @@ static void put_prev_task_rt(struct rq *rq, struct task_struct *p)
> */
> if (on_rt_rq(&p->rt) && p->nr_cpus_allowed > 1)
> enqueue_pushable_task(rq, p);
> +
> + if (rf && !on_rt_rq(&p->rt) && need_pull_rt_task(rq, p)) {
> + /*
> + * This is OK, because current is on_cpu, which avoids it being
> + * picked for load-balance and preemption/IRQs are still
> + * disabled avoiding further scheduler activity on it and we've
> + * not yet started the picking loop.
> + */
> + rq_unpin_lock(rq, rf);
> + pull_rt_task(rq);
> + rq_repin_lock(rq, rf);
> + }
> }
>
> #ifdef CONFIG_SMP
> diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
> index bfcbcbb25646..4cbe2bef92e4 100644
> --- a/kernel/sched/sched.h
> +++ b/kernel/sched/sched.h
> @@ -1675,7 +1675,7 @@ struct sched_class {
> struct task_struct * (*pick_next_task)(struct rq *rq,
> struct task_struct *prev,
> struct rq_flags *rf);
> - void (*put_prev_task)(struct rq *rq, struct task_struct *p);
> + void (*put_prev_task)(struct rq *rq, struct task_struct *p, struct rq_flags *rf);
> void (*set_next_task)(struct rq *rq, struct task_struct *p);
>
> #ifdef CONFIG_SMP
> @@ -1721,7 +1721,7 @@ struct sched_class {
> static inline void put_prev_task(struct rq *rq, struct task_struct *prev)
> {
> WARN_ON_ONCE(rq->curr != prev);
> - prev->sched_class->put_prev_task(rq, prev);
> + prev->sched_class->put_prev_task(rq, prev, NULL);
> }
>
> static inline void set_next_task(struct rq *rq, struct task_struct *next)
> diff --git a/kernel/sched/stop_task.c b/kernel/sched/stop_task.c
> index 47a3d2a18a9a..8f414018d5e0 100644
> --- a/kernel/sched/stop_task.c
> +++ b/kernel/sched/stop_task.c
> @@ -59,7 +59,7 @@ static void yield_task_stop(struct rq *rq)
> BUG(); /* the stop task should never yield, its pointless. */
> }
>
> -static void put_prev_task_stop(struct rq *rq, struct task_struct *prev)
> +static void put_prev_task_stop(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
> {
> struct task_struct *curr = rq->curr;
> u64 delta_exec;
> --
> 2.17.1
>
next prev parent reply other threads:[~2019-08-26 16:51 UTC|newest]
Thread overview: 161+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-29 20:36 [RFC PATCH v3 00/16] Core scheduling v3 Vineeth Remanan Pillai
2019-05-29 20:36 ` [RFC PATCH v3 01/16] stop_machine: Fix stop_cpus_in_progress ordering Vineeth Remanan Pillai
2019-08-08 10:54 ` [tip:sched/core] " tip-bot for Peter Zijlstra
2019-08-26 16:19 ` [RFC PATCH v3 01/16] " mark gross
2019-08-26 16:59 ` Peter Zijlstra
2019-05-29 20:36 ` [RFC PATCH v3 02/16] sched: Fix kerneldoc comment for ia64_set_curr_task Vineeth Remanan Pillai
2019-08-08 10:55 ` [tip:sched/core] " tip-bot for Peter Zijlstra
2019-08-26 16:20 ` [RFC PATCH v3 02/16] " mark gross
2019-05-29 20:36 ` [RFC PATCH v3 03/16] sched: Wrap rq::lock access Vineeth Remanan Pillai
2019-05-29 20:36 ` [RFC PATCH v3 04/16] sched/{rt,deadline}: Fix set_next_task vs pick_next_task Vineeth Remanan Pillai
2019-08-08 10:55 ` [tip:sched/core] " tip-bot for Peter Zijlstra
2019-05-29 20:36 ` [RFC PATCH v3 05/16] sched: Add task_struct pointer to sched_class::set_curr_task Vineeth Remanan Pillai
2019-08-08 10:57 ` [tip:sched/core] " tip-bot for Peter Zijlstra
2019-05-29 20:36 ` [RFC PATCH v3 06/16] sched/fair: Export newidle_balance() Vineeth Remanan Pillai
2019-08-08 10:58 ` [tip:sched/core] sched/fair: Expose newidle_balance() tip-bot for Peter Zijlstra
2019-05-29 20:36 ` [RFC PATCH v3 07/16] sched: Allow put_prev_task() to drop rq->lock Vineeth Remanan Pillai
2019-08-08 10:58 ` [tip:sched/core] " tip-bot for Peter Zijlstra
2019-08-26 16:51 ` mark gross [this message]
2019-05-29 20:36 ` [RFC PATCH v3 08/16] sched: Rework pick_next_task() slow-path Vineeth Remanan Pillai
2019-08-08 10:59 ` [tip:sched/core] " tip-bot for Peter Zijlstra
2019-08-26 17:01 ` [RFC PATCH v3 08/16] " mark gross
2019-05-29 20:36 ` [RFC PATCH v3 09/16] sched: Introduce sched_class::pick_task() Vineeth Remanan Pillai
2019-08-26 17:14 ` mark gross
2019-05-29 20:36 ` [RFC PATCH v3 10/16] sched: Core-wide rq->lock Vineeth Remanan Pillai
2019-05-31 11:08 ` Peter Zijlstra
2019-05-31 15:23 ` Vineeth Pillai
2019-05-29 20:36 ` [RFC PATCH v3 11/16] sched: Basic tracking of matching tasks Vineeth Remanan Pillai
2019-08-26 20:59 ` mark gross
2019-05-29 20:36 ` [RFC PATCH v3 12/16] sched: A quick and dirty cgroup tagging interface Vineeth Remanan Pillai
2019-05-29 20:36 ` [RFC PATCH v3 13/16] sched: Add core wide task selection and scheduling Vineeth Remanan Pillai
2019-06-07 23:36 ` Pawan Gupta
2019-05-29 20:36 ` [RFC PATCH v3 14/16] sched/fair: Add a few assertions Vineeth Remanan Pillai
2019-05-29 20:36 ` [RFC PATCH v3 15/16] sched: Trivial forced-newidle balancer Vineeth Remanan Pillai
2019-05-29 20:36 ` [RFC PATCH v3 16/16] sched: Debug bits Vineeth Remanan Pillai
2019-05-29 21:02 ` Peter Oskolkov
2019-05-30 14:04 ` [RFC PATCH v3 00/16] Core scheduling v3 Aubrey Li
2019-05-30 14:17 ` Julien Desfossez
2019-05-31 4:55 ` Aubrey Li
2019-05-31 3:01 ` Aaron Lu
2019-05-31 5:12 ` Aubrey Li
2019-05-31 6:09 ` Aaron Lu
2019-05-31 6:53 ` Aubrey Li
2019-05-31 7:44 ` Aaron Lu
2019-05-31 8:26 ` Aubrey Li
2019-05-31 21:08 ` Julien Desfossez
2019-06-06 15:26 ` Julien Desfossez
2019-06-12 1:52 ` Li, Aubrey
2019-06-12 16:06 ` Julien Desfossez
2019-06-12 16:33 ` Julien Desfossez
2019-06-13 0:03 ` Subhra Mazumdar
2019-06-13 3:22 ` Julien Desfossez
2019-06-17 2:51 ` Aubrey Li
2019-06-19 18:33 ` Julien Desfossez
2019-07-18 10:07 ` Aaron Lu
2019-07-18 23:27 ` Tim Chen
2019-07-19 5:52 ` Aaron Lu
2019-07-19 11:48 ` Aubrey Li
2019-07-19 18:33 ` Tim Chen
2019-07-22 10:26 ` Aubrey Li
2019-07-22 10:43 ` Aaron Lu
2019-07-23 2:52 ` Aubrey Li
2019-07-25 14:30 ` Aaron Lu
2019-07-25 14:31 ` [RFC PATCH 1/3] wrapper for cfs_rq->min_vruntime Aaron Lu
2019-07-25 14:32 ` [PATCH 2/3] core vruntime comparison Aaron Lu
2019-08-06 14:17 ` Peter Zijlstra
2019-07-25 14:33 ` [PATCH 3/3] temp hack to make tick based schedule happen Aaron Lu
2019-07-25 21:42 ` [RFC PATCH v3 00/16] Core scheduling v3 Li, Aubrey
2019-07-26 15:21 ` Julien Desfossez
2019-07-26 21:29 ` Tim Chen
2019-07-31 2:42 ` Li, Aubrey
2019-08-02 15:37 ` Julien Desfossez
2019-08-05 15:55 ` Tim Chen
2019-08-06 3:24 ` Aaron Lu
2019-08-06 6:56 ` Aubrey Li
2019-08-06 7:04 ` Aaron Lu
2019-08-06 12:24 ` Vineeth Remanan Pillai
2019-08-06 13:49 ` Aaron Lu
2019-08-06 16:14 ` Vineeth Remanan Pillai
2019-08-06 14:16 ` Peter Zijlstra
2019-08-06 15:53 ` Vineeth Remanan Pillai
2019-08-06 17:03 ` Tim Chen
2019-08-06 17:12 ` Peter Zijlstra
2019-08-06 21:19 ` Tim Chen
2019-08-08 6:47 ` Aaron Lu
2019-08-08 17:27 ` Tim Chen
2019-08-08 21:42 ` Tim Chen
2019-08-10 14:15 ` Aaron Lu
2019-08-12 15:38 ` Vineeth Remanan Pillai
2019-08-13 2:24 ` Aaron Lu
2019-08-08 12:55 ` Aaron Lu
2019-08-08 16:39 ` Tim Chen
2019-08-10 14:18 ` Aaron Lu
2019-08-05 20:09 ` Phil Auld
2019-08-06 13:54 ` Aaron Lu
2019-08-06 14:17 ` Phil Auld
2019-08-06 14:41 ` Aaron Lu
2019-08-06 14:55 ` Phil Auld
2019-08-07 8:58 ` Dario Faggioli
2019-08-07 17:10 ` Tim Chen
2019-08-15 16:09 ` Dario Faggioli
2019-08-16 2:33 ` Aaron Lu
2019-09-05 1:44 ` Julien Desfossez
2019-09-06 22:17 ` Tim Chen
2019-09-18 21:27 ` Tim Chen
2019-09-06 18:30 ` Tim Chen
2019-09-11 14:02 ` Aaron Lu
2019-09-11 16:19 ` Tim Chen
2019-09-11 16:47 ` Vineeth Remanan Pillai
2019-09-12 12:35 ` Aaron Lu
2019-09-12 17:29 ` Tim Chen
2019-09-13 14:15 ` Aaron Lu
2019-09-13 17:13 ` Tim Chen
2019-09-30 11:53 ` Vineeth Remanan Pillai
2019-10-02 20:48 ` Vineeth Remanan Pillai
2019-10-10 13:54 ` Aaron Lu
2019-10-10 14:29 ` Vineeth Remanan Pillai
2019-10-11 7:33 ` Aaron Lu
2019-10-11 11:32 ` Vineeth Remanan Pillai
2019-10-11 12:01 ` Aaron Lu
2019-10-11 12:10 ` Vineeth Remanan Pillai
2019-10-12 3:55 ` Aaron Lu
2019-10-13 12:44 ` Vineeth Remanan Pillai
2019-10-14 9:57 ` Aaron Lu
2019-10-21 12:30 ` Vineeth Remanan Pillai
2019-09-12 12:04 ` Aaron Lu
2019-09-12 17:05 ` Tim Chen
2019-09-13 13:57 ` Aaron Lu
2019-09-12 23:12 ` Aubrey Li
2019-09-15 14:14 ` Aaron Lu
2019-09-18 1:33 ` Aubrey Li
2019-09-18 20:40 ` Tim Chen
2019-09-18 22:16 ` Aubrey Li
2019-09-30 14:36 ` Vineeth Remanan Pillai
2019-10-29 20:40 ` Julien Desfossez
2019-11-01 21:42 ` Tim Chen
2019-10-29 9:11 ` Dario Faggioli
2019-10-29 9:15 ` Dario Faggioli
2019-10-29 9:16 ` Dario Faggioli
2019-10-29 9:17 ` Dario Faggioli
2019-10-29 9:18 ` Dario Faggioli
2019-10-29 9:18 ` Dario Faggioli
2019-10-29 9:19 ` Dario Faggioli
2019-10-29 9:20 ` Dario Faggioli
2019-10-29 20:34 ` Julien Desfossez
2019-11-15 16:30 ` Dario Faggioli
2019-09-25 2:40 ` Aubrey Li
2019-09-25 17:24 ` Tim Chen
2019-09-25 22:07 ` Aubrey Li
2019-09-30 15:22 ` Julien Desfossez
2019-08-27 21:14 ` Matthew Garrett
2019-08-27 21:50 ` Peter Zijlstra
2019-08-28 15:30 ` Phil Auld
2019-08-28 16:01 ` Peter Zijlstra
2019-08-28 16:37 ` Tim Chen
2019-08-29 14:30 ` Phil Auld
2019-08-29 14:38 ` Peter Zijlstra
2019-09-10 14:27 ` Julien Desfossez
2019-09-18 21:12 ` Tim Chen
2019-08-28 15:59 ` Tim Chen
2019-08-28 16:16 ` Peter Zijlstra
2019-08-27 23:24 ` Aubrey Li
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