From: Aaron Lu <aaron.lu@linux.alibaba.com>
To: Tim Chen <tim.c.chen@linux.intel.com>
Cc: "Peter Zijlstra" <peterz@infradead.org>,
"Julien Desfossez" <jdesfossez@digitalocean.com>,
"Li, Aubrey" <aubrey.li@linux.intel.com>,
"Aubrey Li" <aubrey.intel@gmail.com>,
"Subhra Mazumdar" <subhra.mazumdar@oracle.com>,
"Vineeth Remanan Pillai" <vpillai@digitalocean.com>,
"Nishanth Aravamudan" <naravamudan@digitalocean.com>,
"Ingo Molnar" <mingo@kernel.org>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Paul Turner" <pjt@google.com>,
"Linus Torvalds" <torvalds@linux-foundation.org>,
"Linux List Kernel Mailing" <linux-kernel@vger.kernel.org>,
"Frédéric Weisbecker" <fweisbec@gmail.com>,
"Kees Cook" <keescook@chromium.org>,
"Greg Kerr" <kerrnel@google.com>, "Phil Auld" <pauld@redhat.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 00/16] Core scheduling v3
Date: Sat, 10 Aug 2019 22:15:56 +0800 [thread overview]
Message-ID: <20190810141556.GA73644@aaronlu> (raw)
In-Reply-To: <b7a83fcb-5c34-9794-5688-55c52697fd84@linux.intel.com>
On Thu, Aug 08, 2019 at 02:42:57PM -0700, Tim Chen wrote:
> On 8/8/19 10:27 AM, Tim Chen wrote:
> > On 8/7/19 11:47 PM, Aaron Lu wrote:
> >> On Tue, Aug 06, 2019 at 02:19:57PM -0700, Tim Chen wrote:
> >>> +void account_core_idletime(struct task_struct *p, u64 exec)
> >>> +{
> >>> + const struct cpumask *smt_mask;
> >>> + struct rq *rq;
> >>> + bool force_idle, refill;
> >>> + int i, cpu;
> >>> +
> >>> + rq = task_rq(p);
> >>> + if (!sched_core_enabled(rq) || !p->core_cookie)
> >>> + return;
> >>
> >> I don't see why return here for untagged task. Untagged task can also
> >> preempt tagged task and force a CPU thread enter idle state.
> >> Untagged is just another tag to me, unless we want to allow untagged
> >> task to coschedule with a tagged task.
> >
> > You are right. This needs to be fixed.
> >
>
> Here's the updated patchset, including Aaron's fix and also
> added accounting of force idle time by deadline and rt tasks.
I have two other small changes that I think are worth sending out.
The first simplify logic in pick_task() and the 2nd avoid task pick all
over again when max is preempted. I also refined the previous hack patch to
make schedule always happen only for root cfs rq. Please see below for
details, thanks.
patch1:
From cea56db35fe9f393c357cdb1bdcb2ef9b56cfe97 Mon Sep 17 00:00:00 2001
From: Aaron Lu <ziqian.lzq@antfin.com>
Date: Mon, 5 Aug 2019 21:21:25 +0800
Subject: [PATCH 1/3] sched/core: simplify pick_task()
No need to special case !cookie case in pick_task(), we just need to
make it possible to return idle in sched_core_find() for !cookie query.
And cookie_pick will always have less priority than class_pick, so
remove the redundant check of prio_less(cookie_pick, class_pick).
Signed-off-by: Aaron Lu <ziqian.lzq@antfin.com>
---
kernel/sched/core.c | 19 ++++---------------
1 file changed, 4 insertions(+), 15 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 90655c9ad937..84fec9933b74 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -186,6 +186,8 @@ static struct task_struct *sched_core_find(struct rq *rq, unsigned long cookie)
* The idle task always matches any cookie!
*/
match = idle_sched_class.pick_task(rq);
+ if (!cookie)
+ goto out;
while (node) {
node_task = container_of(node, struct task_struct, core_node);
@@ -199,7 +201,7 @@ static struct task_struct *sched_core_find(struct rq *rq, unsigned long cookie)
node = node->rb_left;
}
}
-
+out:
return match;
}
@@ -3657,18 +3659,6 @@ pick_task(struct rq *rq, const struct sched_class *class, struct task_struct *ma
if (!class_pick)
return NULL;
- if (!cookie) {
- /*
- * If class_pick is tagged, return it only if it has
- * higher priority than max.
- */
- if (max && class_pick->core_cookie &&
- prio_less(class_pick, max))
- return idle_sched_class.pick_task(rq);
-
- return class_pick;
- }
-
/*
* If class_pick is idle or matches cookie, return early.
*/
@@ -3682,8 +3672,7 @@ pick_task(struct rq *rq, const struct sched_class *class, struct task_struct *ma
* the core (so far) and it must be selected, otherwise we must go with
* the cookie pick in order to satisfy the constraint.
*/
- if (prio_less(cookie_pick, class_pick) &&
- (!max || prio_less(max, class_pick)))
+ if (!max || prio_less(max, class_pick))
return class_pick;
return cookie_pick;
--
2.19.1.3.ge56e4f7
patch2:
From 487950dc53a40d5c566602f775ce46a0bab7a412 Mon Sep 17 00:00:00 2001
From: Aaron Lu <ziqian.lzq@antfin.com>
Date: Fri, 9 Aug 2019 14:48:01 +0800
Subject: [PATCH 2/3] sched/core: no need to pick again after max is preempted
When sibling's task preempts current max, there is no need to do the
pick all over again - the preempted cpu could just pick idle and done.
Signed-off-by: Aaron Lu <ziqian.lzq@antfin.com>
---
kernel/sched/core.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 84fec9933b74..e88583860abe 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3756,7 +3756,6 @@ pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
* order.
*/
for_each_class(class) {
-again:
for_each_cpu_wrap(i, smt_mask, cpu) {
struct rq *rq_i = cpu_rq(i);
struct task_struct *p;
@@ -3828,10 +3827,10 @@ pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
if (j == i)
continue;
- cpu_rq(j)->core_pick = NULL;
+ cpu_rq(j)->core_pick = idle_sched_class.pick_task(cpu_rq(j));
}
occ = 1;
- goto again;
+ goto out;
} else {
/*
* Once we select a task for a cpu, we
@@ -3846,7 +3845,7 @@ pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
}
next_class:;
}
-
+out:
rq->core->core_pick_seq = rq->core->core_task_seq;
next = rq->core_pick;
rq->core_sched_seq = rq->core->core_pick_seq;
--
2.19.1.3.ge56e4f7
patch3:
From 2d396d99e0dd7157b0b4f7a037c8b84ed135ea56 Mon Sep 17 00:00:00 2001
From: Aaron Lu <ziqian.lzq@antfin.com>
Date: Thu, 25 Jul 2019 19:57:21 +0800
Subject: [PATCH 3/3] sched/fair: make tick based schedule always happen
When a hyperthread is forced idle and the other hyperthread has a single
CPU intensive task running, the running task can occupy the hyperthread
for a long time with no scheduling point and starve the other
hyperthread.
Fix this temporarily by always checking if the task has exceed its
timeslice and if so, for root cfs_rq, do a schedule.
Signed-off-by: Aaron Lu <ziqian.lzq@antfin.com>
---
kernel/sched/fair.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 26d29126d6a5..b1f0defdad91 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4011,6 +4011,9 @@ check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
return;
}
+ if (cfs_rq->nr_running <= 1)
+ return;
+
/*
* Ensure that a task that missed wakeup preemption by a
* narrow margin doesn't have to wait for a full slice.
@@ -4179,7 +4182,7 @@ entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr, int queued)
return;
#endif
- if (cfs_rq->nr_running > 1)
+ if (cfs_rq->nr_running > 1 || cfs_rq->tg == &root_task_group)
check_preempt_tick(cfs_rq, curr);
}
--
2.19.1.3.ge56e4f7
next prev parent reply other threads:[~2019-08-10 14:16 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 ` [RFC PATCH v3 07/16] " mark gross
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 [this message]
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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