From: vincent.guittot@linaro.org (Vincent Guittot)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v5 08/12] sched: move cfs task on a CPU with higher capacity
Date: Wed, 3 Sep 2014 14:49:32 +0200 [thread overview]
Message-ID: <CAKfTPtDH5-7cW8=x-wooSn9Vui28h-KP6ACX1CefxHZHf=XHHQ@mail.gmail.com> (raw)
In-Reply-To: <540708DC.9060901@linux.vnet.ibm.com>
On 3 September 2014 14:26, Preeti U Murthy <preeti@linux.vnet.ibm.com> wrote:
> On 09/03/2014 05:14 PM, Vincent Guittot wrote:
>> On 3 September 2014 11:11, Preeti U Murthy <preeti@linux.vnet.ibm.com> wrote:
>>> On 09/01/2014 02:15 PM, Vincent Guittot wrote:
[snip]
>>>
>>> Ok I understand your explanation above. But I was wondering if you would
>>> need to add this check around rq->cfs.h_nr_running >= 1 in the above two
>>> cases as well.
>>
>> yes you're right for the test if (rq->nr_running >= 2).
>>
>> It's not so straight forward for nr_busy_cpus which reflects how many
>> CPUs have not stopped their tick. The scheduler assumes that the
>> latter are busy with cfs tasks
>>
>>>
>>> I have actually raised this concern over whether we should be using
>>> rq->nr_running or cfs_rq->nr_running while we do load balancing in reply
>>> to your patch3. While all our load measurements are about the cfs_rq
>>
>> I have just replied to your comments on patch 3. Sorry for the delay
>>
>>> load, we use rq->nr_running, which may include tasks from other sched
>>> classes as well. We divide them to get average load per task during load
>>> balancing which is wrong, isn't it? Similarly during nohz_kick_needed(),
>>> we trigger load balancing based on rq->nr_running again.
>>>
>>> In this patch too, even if you know that the cpu is being dominated by
>>> tasks that do not belong to cfs class, you would be triggering a futile
>>> load balance if there are no fair tasks to move.
>> This patch adds one additional condition that is based on
>> rq->cfs.h_nr_running so it should not trigger any futile load balance.
>> Then, I have also take advantage of this patch to clean up
>> nohz_kick_needed as proposed by Peter but the conditions are the same
>> than previously (except the one with rq->cfs.h_nr_running)
>>
>> I can prepare another patchset that will solve the concerns that you
>> raised for nohz_kick_needed and in patch 3 but i would prefer not
>> include them in this patchset which is large enough and which subject
>> is a bit different.
>> Does it seem ok for you ?
>
> Sure Vincent, thanks! I have in fact sent out a mail raising my concern
> over rq->nr_running. If others agree on the issue to be existing, maybe
> we can work on this next patchset that can clean this up in all places
> necessary and not just in nohz_kick_needed().
Ok, let continue this discussion on the other thread
Regards,
Vincent
>
> Regards
> Preeti U Murthy
>>
>> Regards,
>> Vincent
>>>
>>> Regards
>>> Preeti U Murthy
>>>
>>
>
next prev parent reply other threads:[~2014-09-03 12:49 UTC|newest]
Thread overview: 79+ 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
2014-08-26 11:06 ` [PATCH v5 02/12] sched: remove a wake_affine condition 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
2014-08-26 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
2014-08-26 11:06 ` [PATCH v5 05/12] ARM: topology: use new cpu_capacity interface Vincent Guittot
2014-09-11 18:52 ` Nicolas Pitre
2014-08-26 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
2014-08-26 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 [this message]
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
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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