From: peterz@infradead•org (Peter Zijlstra)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH v2 10/11] sched: move cfs task on a CPU with higher capacity
Date: Thu, 29 May 2014 11:50:24 +0200 [thread overview]
Message-ID: <20140529095024.GF11074@laptop.programming.kicks-ass.net> (raw)
In-Reply-To: <1400860385-14555-11-git-send-email-vincent.guittot@linaro.org>
On Fri, May 23, 2014 at 05:53:04PM +0200, Vincent Guittot wrote:
> If the CPU is used for handling lot of IRQs, trig a load balance to check if
> it's worth moving its tasks on another CPU that has more capacity
>
> Signed-off-by: Vincent Guittot <vincent.guittot@linaro•org>
> ---
> kernel/sched/fair.c | 13 +++++++++++++
> 1 file changed, 13 insertions(+)
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index e8a30f9..2501e49 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -5948,6 +5948,13 @@ static bool update_sd_pick_busiest(struct lb_env *env,
> if (sgs->sum_nr_running > sgs->group_capacity)
> return true;
>
> + /*
> + * The group capacity is reduced probably because of activity from other
> + * sched class or interrupts which use part of the available capacity
> + */
> + if ((sg->sgp->power_orig * 100) > (sgs->group_power * env->sd->imbalance_pct))
> + return true;
> +
> if (sgs->group_imb)
> return true;
>
But we should already do this because the load numbers are scaled with
the power/capacity figures. If one CPU gets significant less time to run
fair tasks, its effective load would spike and it'd get to be selected
here anyway.
Or am I missing something?
> @@ -7282,6 +7289,12 @@ static inline int nohz_kick_needed(struct rq *rq)
>
> if (nr_busy > 1)
> goto need_kick_unlock;
> +
> + if ((rq->cfs.h_nr_running >= 1)
> + && ((rq->cpu_power * sd->imbalance_pct) <
> + (rq->cpu_power_orig * 100)))
> + goto need_kick_unlock;
> +
> }
>
> sd = rcu_dereference(per_cpu(sd_asym, cpu));
OK, so there you're kicking the idle balancer to try and get another CPU
to pull some load? That makes sense I suppose.
That function is pretty horrible though; how about something like this
first?
---
kernel/sched/fair.c | 29 +++++++++++++----------------
1 file changed, 13 insertions(+), 16 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index c9617b73bcc0..47fb96e6fa83 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -7215,15 +7215,16 @@ static void nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle)
* - For SD_ASYM_PACKING, if the lower numbered cpu's in the scheduler
* domain span are idle.
*/
-static inline int nohz_kick_needed(struct rq *rq)
+static inline bool nohz_kick_needed(struct rq *rq)
{
unsigned long now = jiffies;
struct sched_domain *sd;
struct sched_group_power *sgp;
int nr_busy, cpu = rq->cpu;
+ bool kick = false;
if (unlikely(rq->idle_balance))
- return 0;
+ return false;
/*
* We may be recently in ticked or tickless idle mode. At the first
@@ -7237,38 +7238,34 @@ static inline int nohz_kick_needed(struct rq *rq)
* balancing.
*/
if (likely(!atomic_read(&nohz.nr_cpus)))
- return 0;
+ return false;
if (time_before(now, nohz.next_balance))
- return 0;
+ return false;
if (rq->nr_running >= 2)
- goto need_kick;
+ return true;
rcu_read_lock();
sd = rcu_dereference(per_cpu(sd_busy, cpu));
-
if (sd) {
sgp = sd->groups->sgp;
nr_busy = atomic_read(&sgp->nr_busy_cpus);
- if (nr_busy > 1)
- goto need_kick_unlock;
+ if (nr_busy > 1) {
+ kick = true;
+ goto unlock;
+ }
}
sd = rcu_dereference(per_cpu(sd_asym, cpu));
-
if (sd && (cpumask_first_and(nohz.idle_cpus_mask,
sched_domain_span(sd)) < cpu))
- goto need_kick_unlock;
-
- rcu_read_unlock();
- return 0;
+ kick = true;
-need_kick_unlock:
+unlock:
rcu_read_unlock();
-need_kick:
- return 1;
+ return kick;
}
#else
static void nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle) { }
next prev parent reply other threads:[~2014-05-29 9:50 UTC|newest]
Thread overview: 108+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-23 15:52 [PATCH v2 00/11] sched: consolidation of cpu_power Vincent Guittot
2014-05-23 15:52 ` [PATCH v2 01/11] sched: fix imbalance flag reset Vincent Guittot
2014-05-25 10:33 ` Preeti U Murthy
2014-05-26 7:49 ` Vincent Guittot
2014-05-26 9:16 ` Preeti U Murthy
2014-05-26 10:14 ` Vincent Guittot
2014-05-23 15:52 ` [PATCH v2 02/11] sched: remove a wake_affine condition Vincent Guittot
2014-05-27 12:48 ` Peter Zijlstra
2014-05-27 15:19 ` Vincent Guittot
2014-05-27 15:39 ` Peter Zijlstra
2014-05-27 16:14 ` Vincent Guittot
2014-05-28 6:49 ` Vincent Guittot
2014-05-28 15:09 ` Dietmar Eggemann
2014-05-28 15:25 ` Vincent Guittot
2014-05-27 13:43 ` Peter Zijlstra
2014-05-27 13:45 ` Peter Zijlstra
2014-05-27 15:20 ` Vincent Guittot
2014-05-23 15:52 ` [PATCH v2 03/11] sched: fix avg_load computation Vincent Guittot
2014-05-27 13:48 ` Peter Zijlstra
2014-05-23 15:52 ` [PATCH v2 04/11] sched: Allow all archs to set the power_orig Vincent Guittot
2014-05-30 14:04 ` Dietmar Eggemann
2014-05-30 14:46 ` Peter Zijlstra
2014-05-30 20:50 ` Vincent Guittot
2014-06-04 9:42 ` Dietmar Eggemann
2014-06-04 11:15 ` Vincent Guittot
2014-06-05 8:59 ` Dietmar Eggemann
2014-06-16 9:01 ` Vincent Guittot
2014-06-03 13:22 ` Morten Rasmussen
2014-06-03 14:02 ` Vincent Guittot
2014-06-04 11:17 ` Morten Rasmussen
2014-06-06 7:01 ` Vincent Guittot
2014-05-23 15:52 ` [PATCH v2 05/11] ARM: topology: use new cpu_power interface Vincent Guittot
2014-05-25 13:22 ` Preeti U Murthy
2014-05-26 8:25 ` Vincent Guittot
2014-05-26 9:19 ` Preeti U Murthy
2014-05-23 15:53 ` [PATCH v2 06/11] sched: add per rq cpu_power_orig Vincent Guittot
2014-05-23 15:53 ` [PATCH v2 07/11] Revert "sched: Put rq's sched_avg under CONFIG_FAIR_GROUP_SCHED" Vincent Guittot
2014-05-23 15:53 ` [PATCH v2 08/11] sched: get CPU's activity statistic Vincent Guittot
2014-05-27 17:32 ` Peter Zijlstra
2014-05-28 7:01 ` Vincent Guittot
2014-05-28 12:10 ` Morten Rasmussen
2014-05-28 13:15 ` Vincent Guittot
2014-05-28 15:47 ` Morten Rasmussen
2014-05-28 16:39 ` Vincent Guittot
2014-06-03 12:03 ` Morten Rasmussen
2014-06-03 15:59 ` Peter Zijlstra
2014-06-03 17:41 ` Morten Rasmussen
2014-06-03 15:50 ` Peter Zijlstra
2014-06-03 17:20 ` Morten Rasmussen
2014-06-04 7:47 ` Vincent Guittot
2014-06-04 8:08 ` Peter Zijlstra
2014-06-04 8:55 ` Morten Rasmussen
2014-06-04 9:23 ` Peter Zijlstra
2014-06-04 9:35 ` Vincent Guittot
2014-06-04 10:25 ` Morten Rasmussen
2014-06-04 9:44 ` Morten Rasmussen
2014-06-04 9:32 ` Vincent Guittot
2014-06-04 10:00 ` Morten Rasmussen
2014-06-04 10:17 ` Peter Zijlstra
2014-06-04 10:36 ` Morten Rasmussen
2014-06-04 10:55 ` Peter Zijlstra
2014-06-04 11:07 ` Vincent Guittot
2014-06-04 11:23 ` Morten Rasmussen
2014-06-04 11:52 ` Vincent Guittot
2014-06-04 13:09 ` Morten Rasmussen
2014-06-04 13:23 ` Morten Rasmussen
2014-05-28 15:17 ` Peter Zijlstra
2014-06-03 15:40 ` Peter Zijlstra
2014-06-03 17:16 ` Morten Rasmussen
2014-06-03 17:37 ` Peter Zijlstra
2014-06-03 17:39 ` Peter Zijlstra
2014-06-03 23:11 ` Yuyang Du
2014-05-30 9:50 ` Dietmar Eggemann
2014-05-30 19:20 ` Vincent Guittot
2014-06-01 11:33 ` Dietmar Eggemann
2014-06-02 14:07 ` Vincent Guittot
2014-05-23 15:53 ` [PATCH v2 09/11] sched: test the cpu's capacity in wake affine Vincent Guittot
2014-05-28 10:58 ` Peter Zijlstra
2014-05-28 11:15 ` Vincent Guittot
2014-11-24 0:34 ` Wanpeng Li
2014-11-24 13:23 ` Vincent Guittot
2014-05-23 15:53 ` [PATCH v2 10/11] sched: move cfs task on a CPU with higher capacity Vincent Guittot
2014-05-29 9:50 ` Peter Zijlstra [this message]
2014-05-29 19:37 ` Vincent Guittot
2014-05-30 6:29 ` Peter Zijlstra
2014-05-30 20:05 ` Vincent Guittot
2014-06-02 17:06 ` Vincent Guittot
2014-06-03 11:15 ` Peter Zijlstra
2014-06-03 12:31 ` Vincent Guittot
2014-05-29 14:04 ` Peter Zijlstra
2014-05-29 19:44 ` Vincent Guittot
2014-05-30 13:26 ` Dietmar Eggemann
2014-05-30 19:24 ` Vincent Guittot
2014-05-30 19:45 ` Nicolas Pitre
2014-05-30 20:07 ` Vincent Guittot
2014-05-23 15:53 ` [PATCH v2 11/11] sched: replace capacity by activity Vincent Guittot
2014-05-29 13:55 ` Peter Zijlstra
2014-05-29 19:51 ` Vincent Guittot
2014-06-02 6:21 ` Preeti U Murthy
2014-06-03 9:50 ` Vincent Guittot
2014-05-29 14:02 ` Peter Zijlstra
2014-05-29 19:56 ` Vincent Guittot
2014-05-30 6:34 ` Peter Zijlstra
2014-05-30 19:13 ` Vincent Guittot
2014-05-26 9:44 ` [PATCH v2 00/11] sched: consolidation of cpu_power Preeti U Murthy
2014-05-26 10:04 ` Vincent Guittot
2014-05-26 15:54 ` Vincent Guittot
2014-05-27 5:47 ` Preeti U Murthy
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20140529095024.GF11074@laptop.programming.kicks-ass.net \
--to=peterz@infradead$(echo .)org \
--cc=linux-arm-kernel@lists$(echo .)infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox