From: Vincent Guittot <vincent.guittot@linaro.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
Preeti U Murthy <preeti@linux.vnet.ibm.com>,
Russell King - ARM Linux <linux@arm.linux.org.uk>,
LAK <linux-arm-kernel@lists.infradead.org>,
Rik van Riel <riel@redhat.com>,
Morten Rasmussen <Morten.Rasmussen@arm.com>,
Mike Galbraith <efault@gmx.de>,
Nicolas Pitre <nicolas.pitre@linaro.org>,
"linaro-kernel@lists.linaro.org" <linaro-kernel@lists.linaro.org>,
Daniel Lezcano <daniel.lezcano@linaro.org>,
Dietmar Eggemann <dietmar.eggemann@arm.com>
Subject: Re: [PATCH v5 08/12] sched: move cfs task on a CPU with higher capacity
Date: Thu, 11 Sep 2014 14:14:52 +0200 [thread overview]
Message-ID: <CAKfTPtDtiTFVtgmM+38Ry-=32=o4NDn8LpPaQomug2NfeO_wnw@mail.gmail.com> (raw)
In-Reply-To: <20140911101308.GU3190@worktop.ger.corp.intel.com>
On 11 September 2014 12:13, Peter Zijlstra <peterz@infradead.org> wrote:
> On Tue, Aug 26, 2014 at 01:06:51PM +0200, Vincent Guittot wrote:
>
>> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
>> index 18db43e..60ae1ce 100644
>> --- a/kernel/sched/fair.c
>> +++ b/kernel/sched/fair.c
>> @@ -6049,6 +6049,14 @@ static bool update_sd_pick_busiest(struct lb_env *env,
>> 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->sgc->capacity_orig * 100) > (sgs->group_capacity *
>> + env->sd->imbalance_pct))
>> + return true;
>> +
>> return false;
>> }
>>
>> @@ -6534,13 +6542,23 @@ static int need_active_balance(struct lb_env *env)
>> struct sched_domain *sd = env->sd;
>>
>> if (env->idle == CPU_NEWLY_IDLE) {
>> + int src_cpu = env->src_cpu;
>>
>> /*
>> * ASYM_PACKING needs to force migrate tasks from busy but
>> * higher numbered CPUs in order to pack all tasks in the
>> * lowest numbered CPUs.
>> */
>> - if ((sd->flags & SD_ASYM_PACKING) && env->src_cpu > env->dst_cpu)
>> + if ((sd->flags & SD_ASYM_PACKING) && src_cpu > env->dst_cpu)
>> + return 1;
>> +
>> + /*
>> + * If the CPUs share their cache and the src_cpu's capacity is
>> + * reduced because of other sched_class or IRQs, we trig an
>> + * active balance to move the task
>> + */
>> + if ((capacity_orig_of(src_cpu) * 100) > (capacity_of(src_cpu) *
>> + sd->imbalance_pct))
>> return 1;
>> }
>
> Should you not also check -- in both cases -- that the destination is
> any better?
The case should have been solved earlier when calculating the
imbalance which should be null if the destination is worse than the
source.
But i haven't formally check that calculate_imbalance correctly
handles that case
>
> Also, there's some obvious repetition going on there, maybe add a
> helper?
yes
>
> Also, both sites should probably ensure they're operating in the
> non-saturated/overloaded scenario. Because as soon as we're completely
> saturated we want SMP nice etc. and that all already works right
> (presumably).
If both are overloaded, calculated_imbalance will cap the max load
that can be pulled so the busiest_group will not become idle
next prev parent reply other threads:[~2014-09-11 12:15 UTC|newest]
Thread overview: 85+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-26 11:06 [PATCH v5 00/12] sched: consolidation of cpu_capacity Vincent Guittot
2014-08-26 11:06 ` [PATCH v5 01/12] sched: fix imbalance flag reset Vincent Guittot
2014-09-19 11:47 ` [tip:sched/core] sched: Fix " tip-bot for Vincent Guittot
2014-08-26 11:06 ` [PATCH v5 02/12] sched: remove a wake_affine condition Vincent Guittot
2014-09-19 11:47 ` [tip:sched/core] sched: Remove a wake_affine() condition tip-bot for Vincent Guittot
2014-08-26 11:06 ` [PATCH v5 03/12] sched: fix avg_load computation Vincent Guittot
2014-08-30 12:00 ` Preeti U Murthy
2014-09-03 11:09 ` Vincent Guittot
2014-09-03 23:43 ` Tim Chen
2014-09-04 7:17 ` Vincent Guittot
2014-09-04 16:26 ` Tim Chen
2014-09-05 11:10 ` Preeti U Murthy
2014-09-19 11:47 ` [tip:sched/core] sched: Fix " tip-bot for Vincent Guittot
2014-08-26 11:06 ` [PATCH v5 04/12] sched: Allow all archs to set the capacity_orig Vincent Guittot
2014-08-27 13:12 ` Kamalesh Babulal
2014-08-30 17:07 ` Preeti U Murthy
2014-09-01 8:05 ` Vincent Guittot
2014-09-03 8:41 ` Preeti U Murthy
2014-09-10 13:50 ` Peter Zijlstra
2014-09-10 14:22 ` Vincent Guittot
2014-09-11 10:36 ` Preeti U Murthy
2014-09-19 11:47 ` [tip:sched/core] sched: Allow all architectures to set ' capacity_orig' tip-bot for Vincent Guittot
2014-08-26 11:06 ` [PATCH v5 05/12] ARM: topology: use new cpu_capacity interface Vincent Guittot
2014-09-11 18:52 ` Nicolas Pitre
2014-09-19 11:48 ` [tip:sched/core] ARM: topology: Use the " tip-bot for Vincent Guittot
2014-08-26 11:06 ` [PATCH v5 06/12] sched: add per rq cpu_capacity_orig Vincent Guittot
2014-08-27 13:32 ` Kamalesh Babulal
2014-08-28 7:34 ` Vincent Guittot
2014-09-10 13:53 ` Peter Zijlstra
2014-09-10 14:19 ` Vincent Guittot
2014-09-11 19:02 ` Nicolas Pitre
2014-09-15 21:22 ` Vincent Guittot
2014-08-26 11:06 ` [PATCH v5 07/12] sched: test the cpu's capacity in wake affine Vincent Guittot
2014-09-10 14:19 ` Peter Zijlstra
2014-09-19 11:48 ` [tip:sched/core] sched: Test the CPU's capacity in wake_affine() tip-bot for Vincent Guittot
2014-08-26 11:06 ` [PATCH v5 08/12] sched: move cfs task on a CPU with higher capacity Vincent Guittot
2014-08-30 17:50 ` Preeti U Murthy
2014-09-01 8:45 ` Vincent Guittot
2014-09-03 9:11 ` Preeti U Murthy
2014-09-03 11:44 ` Vincent Guittot
2014-09-03 12:26 ` Preeti U Murthy
2014-09-03 12:49 ` Vincent Guittot
2014-09-11 9:27 ` Peter Zijlstra
2014-09-05 12:06 ` Preeti U Murthy
2014-09-05 12:24 ` Vincent Guittot
2014-09-11 10:07 ` Peter Zijlstra
2014-09-11 11:20 ` Vincent Guittot
2014-09-11 10:13 ` Peter Zijlstra
2014-09-11 12:14 ` Vincent Guittot [this message]
2014-09-11 11:54 ` Peter Zijlstra
2014-08-26 11:06 ` [PATCH v5 09/12] sched: add usage_load_avg Vincent Guittot
2014-09-04 7:34 ` [PATCH v5 09/11] " Vincent Guittot
2014-09-11 11:17 ` Peter Zijlstra
2014-09-11 11:17 ` [PATCH v5 09/12] " Peter Zijlstra
2014-09-11 12:18 ` Vincent Guittot
2014-09-11 12:20 ` Vincent Guittot
2014-09-15 19:15 ` Morten Rasmussen
2014-09-15 22:33 ` Vincent Guittot
2014-08-26 11:06 ` [PATCH v5 10/12] sched: get CPU's utilization statistic Vincent Guittot
2014-09-11 12:34 ` Peter Zijlstra
2014-09-11 13:07 ` Vincent Guittot
2014-09-11 14:04 ` Peter Zijlstra
2014-09-11 19:17 ` Nicolas Pitre
2014-09-12 7:41 ` Vincent Guittot
2014-09-15 19:45 ` Morten Rasmussen
2014-09-16 22:43 ` Vincent Guittot
2014-09-15 19:28 ` Morten Rasmussen
2014-08-26 11:06 ` [PATCH v5 11/12] sched: replace capacity_factor by utilization Vincent Guittot
2014-09-11 15:39 ` Peter Zijlstra
2014-09-11 16:15 ` Peter Zijlstra
2014-09-11 17:26 ` Vincent Guittot
2014-09-14 19:41 ` Peter Zijlstra
2014-09-14 19:51 ` Peter Zijlstra
2014-09-15 11:42 ` Peter Zijlstra
2014-09-15 19:07 ` Nicolas Pitre
2014-09-15 20:01 ` Peter Zijlstra
2014-09-17 18:45 ` Morten Rasmussen
2014-09-17 18:58 ` Morten Rasmussen
2014-09-17 23:03 ` Peter Zijlstra
2014-09-15 22:14 ` Vincent Guittot
2014-09-15 22:18 ` Vincent Guittot
2014-09-17 22:25 ` Peter Zijlstra
2014-09-18 1:32 ` Vincent Guittot
2014-09-16 17:00 ` Dietmar Eggemann
2014-08-26 11:06 ` [PATCH v5 12/12] sched: add SD_PREFER_SIBLING for SMT level Vincent Guittot
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