From: Dietmar Eggemann <dietmar.eggemann@arm.com>
To: Morten Rasmussen <morten.rasmussen@arm.com>,
"peterz@infradead.org" <peterz@infradead.org>,
"mingo@redhat.com" <mingo@redhat.com>
Cc: "vincent.guittot@linaro.org" <vincent.guittot@linaro.org>,
"yuyang.du@intel.com" <yuyang.du@intel.com>,
"preeti@linux.vnet.ibm.com" <preeti@linux.vnet.ibm.com>,
"mturquette@linaro.org" <mturquette@linaro.org>,
"nico@linaro.org" <nico@linaro.org>,
"rjw@rjwysocki.net" <rjw@rjwysocki.net>,
Juri Lelli <Juri.Lelli@arm.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [RFCv3 PATCH 48/48] sched: Disable energy-unfriendly nohz kicks
Date: Fri, 20 Feb 2015 19:26:38 +0000 [thread overview]
Message-ID: <54E78A6E.30301@arm.com> (raw)
In-Reply-To: <1423074685-6336-49-git-send-email-morten.rasmussen@arm.com>
Hi Morten,
On 04/02/15 18:31, Morten Rasmussen wrote:
> With energy-aware scheduling enabled nohz_kick_needed() generates many
> nohz idle-balance kicks which lead to nothing when multiple tasks get
> packed on a single cpu to save energy. This causes unnecessary wake-ups
> and hence wastes energy. Make these conditions depend on !energy_aware()
> for now until the energy-aware nohz story gets sorted out.
>
> cc: Ingo Molnar <mingo@redhat.com>
> cc: Peter Zijlstra <peterz@infradead.org>
>
> Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
> ---
> kernel/sched/fair.c | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 1c248f8..cfe65ae 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -8195,6 +8195,8 @@ static void nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle)
> clear_bit(NOHZ_BALANCE_KICK, nohz_flags(this_cpu));
> }
>
> +static int cpu_overutilized(int cpu, struct sched_domain *sd);
> +
> /*
> * Current heuristic for kicking the idle load balancer in the presence
> * of an idle cpu in the system.
> @@ -8234,12 +8236,13 @@ static inline bool nohz_kick_needed(struct rq *rq)
> if (time_before(now, nohz.next_balance))
> return false;
>
> - if (rq->nr_running >= 2)
> + sd = rcu_dereference(rq->sd);
> + if (rq->nr_running >= 2 && (!energy_aware() || cpu_overutilized(cpu, sd)))
> return true;
CONFIG_PROVE_RCU checking revealed this one:
[ 3.814454] ===============================
[ 3.826989] [ INFO: suspicious RCU usage. ]
[ 3.839526] 3.19.0-rc7+ #10 Not tainted
[ 3.851018] -------------------------------
[ 3.863554] kernel/sched/fair.c:8239 suspicious
rcu_dereference_check() usage!
[ 3.885216]
[ 3.885216] other info that might help us debug this:
[ 3.885216]
[ 3.909236]
[ 3.909236] rcu_scheduler_active = 1, debug_locks = 1
[ 3.928817] no locks held by kthreadd/437.
The RCU read-side critical section has to be extended to incorporate
this sd = rcu_dereference(rq->sd):
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index cfe65aec3237..145360ee6e4a 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -8236,11 +8236,13 @@ static inline bool nohz_kick_needed(struct rq *rq)
if (time_before(now, nohz.next_balance))
return false;
+ rcu_read_lock();
sd = rcu_dereference(rq->sd);
- if (rq->nr_running >= 2 && (!energy_aware() ||
cpu_overutilized(cpu, sd)))
- return true;
+ if (rq->nr_running >= 2 && (!energy_aware() ||
cpu_overutilized(cpu, sd))) {
+ kick = true;
+ goto unlock;
+ }
- rcu_read_lock();
sd = rcu_dereference(per_cpu(sd_busy, cpu));
if (sd && !energy_aware()) {
sgc = sd->groups->sgc;
-- Dietmar
>
> rcu_read_lock();
> sd = rcu_dereference(per_cpu(sd_busy, cpu));
> - if (sd) {
> + if (sd && !energy_aware()) {
> sgc = sd->groups->sgc;
> nr_busy = atomic_read(&sgc->nr_busy_cpus);
>
>
next prev parent reply other threads:[~2015-02-20 19:26 UTC|newest]
Thread overview: 124+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-02-04 18:30 [RFCv3 PATCH 00/48] sched: Energy cost model for energy-aware scheduling Morten Rasmussen
2015-02-04 18:30 ` [RFCv3 PATCH 01/48] sched: add utilization_avg_contrib Morten Rasmussen
2015-02-11 8:50 ` Preeti U Murthy
2015-02-12 1:07 ` Vincent Guittot
2015-02-04 18:30 ` [RFCv3 PATCH 02/48] sched: Track group sched_entity usage contributions Morten Rasmussen
2015-02-04 18:30 ` [RFCv3 PATCH 03/48] sched: remove frequency scaling from cpu_capacity Morten Rasmussen
2015-02-04 18:30 ` [RFCv3 PATCH 04/48] sched: Make sched entity usage tracking frequency-invariant Morten Rasmussen
2015-02-04 18:30 ` [RFCv3 PATCH 05/48] sched: make scale_rt invariant with frequency Morten Rasmussen
2015-02-04 18:30 ` [RFCv3 PATCH 06/48] sched: add per rq cpu_capacity_orig Morten Rasmussen
2015-02-04 18:30 ` [RFCv3 PATCH 07/48] sched: get CPU's usage statistic Morten Rasmussen
2015-02-04 18:30 ` [RFCv3 PATCH 08/48] sched: replace capacity_factor by usage Morten Rasmussen
2015-02-04 18:30 ` [RFCv3 PATCH 09/48] sched: add SD_PREFER_SIBLING for SMT level Morten Rasmussen
2015-02-04 18:30 ` [RFCv3 PATCH 10/48] sched: move cfs task on a CPU with higher capacity Morten Rasmussen
2015-02-04 18:30 ` [RFCv3 PATCH 11/48] sched: Make load tracking frequency scale-invariant Morten Rasmussen
2015-02-04 18:30 ` [RFCv3 PATCH 12/48] sched: Make usage tracking cpu scale-invariant Morten Rasmussen
2015-03-23 14:46 ` Peter Zijlstra
2015-03-23 19:19 ` Dietmar Eggemann
[not found] ` <OF8A3E3617.0D4400A5-ON48257E3A.001B38D9-48257E3A.002379A4@zte.com.cn>
2015-05-06 9:49 ` Dietmar Eggemann
2015-02-04 18:30 ` [RFCv3 PATCH 13/48] cpufreq: Architecture specific callback for frequency changes Morten Rasmussen
2015-02-04 18:30 ` [RFCv3 PATCH 14/48] arm: Frequency invariant scheduler load-tracking support Morten Rasmussen
2015-03-23 13:39 ` Peter Zijlstra
2015-03-24 9:41 ` Morten Rasmussen
2015-02-04 18:30 ` [RFCv3 PATCH 15/48] arm: vexpress: Add CPU clock-frequencies to TC2 device-tree Morten Rasmussen
2015-02-04 18:30 ` [RFCv3 PATCH 16/48] arm: Cpu invariant scheduler load-tracking support Morten Rasmussen
2015-02-04 18:30 ` [RFCv3 PATCH 17/48] sched: Get rid of scaling usage by cpu_capacity_orig Morten Rasmussen
[not found] ` <OFFC493540.15A92099-ON48257E35.0026F60C-48257E35.0027A5FB@zte.com.cn>
2015-04-28 16:54 ` Dietmar Eggemann
2015-02-04 18:30 ` [RFCv3 PATCH 18/48] sched: Track blocked utilization contributions Morten Rasmussen
2015-03-23 14:08 ` Peter Zijlstra
2015-03-24 9:43 ` Morten Rasmussen
2015-03-24 16:07 ` Peter Zijlstra
2015-03-24 17:44 ` Morten Rasmussen
2015-02-04 18:30 ` [RFCv3 PATCH 19/48] sched: Include blocked utilization in usage tracking Morten Rasmussen
2015-02-04 18:30 ` [RFCv3 PATCH 20/48] sched: Documentation for scheduler energy cost model Morten Rasmussen
2015-02-04 18:30 ` [RFCv3 PATCH 21/48] sched: Make energy awareness a sched feature Morten Rasmussen
2015-02-04 18:30 ` [RFCv3 PATCH 22/48] sched: Introduce energy data structures Morten Rasmussen
2015-02-04 18:31 ` [RFCv3 PATCH 23/48] sched: Allocate and initialize " Morten Rasmussen
[not found] ` <OF29F384AC.37929D8E-ON48257E35.002FCB0C-48257E35.003156FE@zte.com.cn>
2015-04-29 15:43 ` Dietmar Eggemann
2015-02-04 18:31 ` [RFCv3 PATCH 24/48] sched: Introduce SD_SHARE_CAP_STATES sched_domain flag Morten Rasmussen
2015-02-04 18:31 ` [RFCv3 PATCH 25/48] arm: topology: Define TC2 energy and provide it to the scheduler Morten Rasmussen
2015-02-04 18:31 ` [RFCv3 PATCH 26/48] sched: Compute cpu capacity available at current frequency Morten Rasmussen
2015-02-04 18:31 ` [RFCv3 PATCH 27/48] sched: Relocated get_cpu_usage() Morten Rasmussen
2015-02-04 18:31 ` [RFCv3 PATCH 28/48] sched: Use capacity_curr to cap utilization in get_cpu_usage() Morten Rasmussen
2015-03-23 16:14 ` Peter Zijlstra
2015-03-24 11:36 ` Morten Rasmussen
2015-03-24 12:59 ` Peter Zijlstra
2015-02-04 18:31 ` [RFCv3 PATCH 29/48] sched: Highest energy aware balancing sched_domain level pointer Morten Rasmussen
2015-03-23 16:16 ` Peter Zijlstra
2015-03-24 10:52 ` Morten Rasmussen
[not found] ` <OF5977496A.A21A7B96-ON48257E35.002EC23C-48257E35.00324DAD@zte.com.cn>
2015-04-29 15:54 ` Dietmar Eggemann
2015-02-04 18:31 ` [RFCv3 PATCH 30/48] sched: Calculate energy consumption of sched_group Morten Rasmussen
2015-03-13 22:54 ` Sai Gurrappadi
2015-03-16 14:15 ` Morten Rasmussen
2015-03-23 16:47 ` Peter Zijlstra
2015-03-23 20:21 ` Dietmar Eggemann
2015-03-24 10:44 ` Morten Rasmussen
2015-03-24 16:10 ` Peter Zijlstra
2015-03-24 17:39 ` Morten Rasmussen
2015-03-26 15:23 ` Dietmar Eggemann
2015-03-20 18:40 ` Sai Gurrappadi
2015-03-27 15:58 ` Morten Rasmussen
2015-02-04 18:31 ` [RFCv3 PATCH 31/48] sched: Extend sched_group_energy to test load-balancing decisions Morten Rasmussen
[not found] ` <OF081FBA75.F80B8844-ON48257E37.00261E89-48257E37.00267F24@zte.com.cn>
2015-04-30 20:26 ` Dietmar Eggemann
2015-02-04 18:31 ` [RFCv3 PATCH 32/48] sched: Estimate energy impact of scheduling decisions Morten Rasmussen
2015-02-04 18:31 ` [RFCv3 PATCH 33/48] sched: Energy-aware wake-up task placement Morten Rasmussen
2015-03-13 22:47 ` Sai Gurrappadi
2015-03-16 14:47 ` Morten Rasmussen
2015-03-18 20:15 ` Sai Gurrappadi
2015-03-27 16:37 ` Morten Rasmussen
2015-03-24 13:00 ` Peter Zijlstra
2015-03-24 15:24 ` Morten Rasmussen
2015-03-24 13:00 ` Peter Zijlstra
2015-03-24 15:42 ` Morten Rasmussen
2015-03-24 15:53 ` Peter Zijlstra
2015-03-24 17:47 ` Morten Rasmussen
2015-03-24 16:35 ` Peter Zijlstra
2015-03-25 18:01 ` Juri Lelli
2015-03-25 18:14 ` Peter Zijlstra
2015-03-26 10:21 ` Juri Lelli
2015-03-26 10:41 ` Peter Zijlstra
2015-04-27 16:01 ` Michael Turquette
2015-04-28 13:06 ` Peter Zijlstra
2015-02-04 18:31 ` [RFCv3 PATCH 34/48] sched: Bias new task wakeups towards higher capacity cpus Morten Rasmussen
2015-03-24 13:33 ` Peter Zijlstra
2015-03-25 18:18 ` Morten Rasmussen
2015-02-04 18:31 ` [RFCv3 PATCH 35/48] sched, cpuidle: Track cpuidle state index in the scheduler Morten Rasmussen
2015-02-04 18:31 ` [RFCv3 PATCH 36/48] sched: Count number of shallower idle-states in struct sched_group_energy Morten Rasmussen
2015-03-24 13:14 ` Peter Zijlstra
2015-03-24 17:13 ` Morten Rasmussen
2015-02-04 18:31 ` [RFCv3 PATCH 37/48] sched: Determine the current sched_group idle-state Morten Rasmussen
[not found] ` <OF1FDC99CD.22435E74-ON48257E37.001BA739-48257E37.001CA5ED@zte.com.cn>
2015-04-30 20:17 ` Dietmar Eggemann
[not found] ` <OF2F4202E4.8A4AF229-ON48257E38.00312CD4-48257E38.0036ADB6@zte.com.cn>
2015-05-01 15:09 ` Dietmar Eggemann
2015-02-04 18:31 ` [RFCv3 PATCH 38/48] sched: Infrastructure to query if load balancing is energy-aware Morten Rasmussen
2015-03-24 13:41 ` Peter Zijlstra
2015-03-24 16:17 ` Dietmar Eggemann
2015-03-24 13:56 ` Peter Zijlstra
2015-03-24 16:22 ` Dietmar Eggemann
2015-02-04 18:31 ` [RFCv3 PATCH 39/48] sched: Introduce energy awareness into update_sg_lb_stats Morten Rasmussen
2015-02-04 18:31 ` [RFCv3 PATCH 40/48] sched: Introduce energy awareness into update_sd_lb_stats Morten Rasmussen
2015-02-04 18:31 ` [RFCv3 PATCH 41/48] sched: Introduce energy awareness into find_busiest_group Morten Rasmussen
2015-02-04 18:31 ` [RFCv3 PATCH 42/48] sched: Introduce energy awareness into find_busiest_queue Morten Rasmussen
2015-03-24 15:21 ` Peter Zijlstra
2015-03-24 18:04 ` Dietmar Eggemann
2015-02-04 18:31 ` [RFCv3 PATCH 43/48] sched: Introduce energy awareness into detach_tasks Morten Rasmussen
2015-03-24 15:25 ` Peter Zijlstra
2015-03-25 23:50 ` Sai Gurrappadi
2015-03-27 15:03 ` Dietmar Eggemann
[not found] ` <OFDCE15EEF.2F536D7F-ON48257E37.002565ED-48257E37.0027A8B9@zte.com.cn>
2015-04-30 20:35 ` Dietmar Eggemann
2015-02-04 18:31 ` [RFCv3 PATCH 44/48] sched: Tipping point from energy-aware to conventional load balancing Morten Rasmussen
2015-03-24 15:26 ` Peter Zijlstra
2015-03-24 18:47 ` Dietmar Eggemann
2015-02-04 18:31 ` [RFCv3 PATCH 45/48] sched: Skip cpu as lb src which has one task and capacity gte the dst cpu Morten Rasmussen
2015-03-24 15:27 ` Peter Zijlstra
2015-03-25 18:44 ` Dietmar Eggemann
[not found] ` <OF9320540C.255228F9-ON48257E37.002A02D1-48257E37.002AB5EE@zte.com.cn>
2015-05-05 10:01 ` Dietmar Eggemann
2015-02-04 18:31 ` [RFCv3 PATCH 46/48] sched: Turn off fast idling of cpus on a partially loaded system Morten Rasmussen
2015-03-24 16:01 ` Peter Zijlstra
2015-02-04 18:31 ` [RFCv3 PATCH 47/48] sched: Enable active migration for cpus of lower capacity Morten Rasmussen
2015-03-24 16:02 ` Peter Zijlstra
2015-02-04 18:31 ` [RFCv3 PATCH 48/48] sched: Disable energy-unfriendly nohz kicks Morten Rasmussen
2015-02-20 19:26 ` Dietmar Eggemann [this message]
2015-04-02 12:43 ` [RFCv3 PATCH 00/48] sched: Energy cost model for energy-aware scheduling Vincent Guittot
2015-04-08 13:33 ` Morten Rasmussen
2015-04-09 7:41 ` Vincent Guittot
2015-04-10 14:46 ` Morten Rasmussen
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=54E78A6E.30301@arm.com \
--to=dietmar.eggemann@arm.com \
--cc=Juri.Lelli@arm.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=morten.rasmussen@arm.com \
--cc=mturquette@linaro.org \
--cc=nico@linaro.org \
--cc=peterz@infradead.org \
--cc=preeti@linux.vnet.ibm.com \
--cc=rjw@rjwysocki.net \
--cc=vincent.guittot@linaro.org \
--cc=yuyang.du@intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
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;
as well as URLs for NNTP newsgroup(s).