From: Dietmar Eggemann <dietmar.eggemann@arm.com>
To: Qais Yousef <qais.yousef@arm.com>, Peter Zijlstra <peterz@infradead.org>
Cc: Thara Gopinath <thara.gopinath@linaro.org>,
mingo@redhat.com, ionela.voinescu@arm.com,
vincent.guittot@linaro.org, rui.zhang@intel.com,
edubezval@gmail.com, qperret@google.com,
linux-kernel@vger.kernel.org, amit.kachhap@gmail.com,
javi.merino@kernel.org, daniel.lezcano@linaro.org
Subject: Re: [Patch v4 4/6] sched/fair: update cpu_capcity to reflect thermal pressure
Date: Thu, 31 Oct 2019 16:38:21 +0100 [thread overview]
Message-ID: <e875ef90-d561-4eee-4951-6556ac89c6a2@arm.com> (raw)
In-Reply-To: <20191031105342.b3sl5xhysldfla3g@e107158-lin.cambridge.arm.com>
On 31.10.19 11:53, Qais Yousef wrote:
> On 10/28/19 16:30, Peter Zijlstra wrote:
>> On Wed, Oct 23, 2019 at 01:28:40PM +0100, Qais Yousef wrote:
>>> On 10/22/19 16:34, Thara Gopinath wrote:
>>>> cpu_capacity relflects the maximum available capacity of a cpu. Thermal
>>>> pressure on a cpu means this maximum available capacity is reduced. This
>>>> patch reduces the average thermal pressure for a cpu from its maximum
>>>> available capacity so that cpu_capacity reflects the actual
>>>> available capacity.
>>>>
>>>> Signed-off-by: Thara Gopinath <thara.gopinath@linaro.org>
>>>> ---
>>>> kernel/sched/fair.c | 1 +
>>>> 1 file changed, 1 insertion(+)
>>>>
>>>> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
>>>> index 4f9c2cb..be3e802 100644
>>>> --- a/kernel/sched/fair.c
>>>> +++ b/kernel/sched/fair.c
>>>> @@ -7727,6 +7727,7 @@ static unsigned long scale_rt_capacity(struct sched_domain *sd, int cpu)
>>>>
>>>> used = READ_ONCE(rq->avg_rt.util_avg);
>>>> used += READ_ONCE(rq->avg_dl.util_avg);
>>>> + used += READ_ONCE(rq->avg_thermal.load_avg);
>>>
>>> Maybe a naive question - but can we add util_avg with load_avg without
>>> a conversion? I thought the 2 signals have different properties.
>>
>> Changelog of patch #1 explains, it's in that dense blob of text.
>>
>> But yes, you're quite right that that wants a comment here.
>
> Thanks for the pointer! A comment would be nice indeed.
>
> To make sure I got this correctly - it's because avg_thermal.load_avg
> represents delta_capacity which is already a 'converted' form of load. So this
> makes avg_thermal.load_avg a util_avg really. Correct?
>
> If I managed to get it right somehow. It'd be nice if we can do inverse
> conversion on delta_capacity so that avg_thermal.{load_avg, util_avg} meaning
> is consistent across the board. But I don't feel strongly about it if this gets
> documented properly.
So why can't we use rq->avg_thermal.util_avg here? Since capacity is
closer to util than to load?
Is it because you want to use the influence of ___update_load_sum(...,
unsigned long load eq. per-cpu delta_capacity in your signal?
Why not call it this way then?
diff --git a/kernel/sched/pelt.c b/kernel/sched/pelt.c
index 38210691c615..d3035457483f 100644
--- a/kernel/sched/pelt.c
+++ b/kernel/sched/pelt.c
@@ -357,9 +357,9 @@ int update_thermal_load_avg(u64 now, struct rq *rq,
u64 capacity)
{
if (___update_load_sum(now, &rq->avg_thermal,
capacity,
- capacity,
- capacity)) {
- ___update_load_avg(&rq->avg_thermal, 1, 1);
+ 0,
+ 0)) {
+ ___update_load_avg(&rq->avg_thermal, 1, 0);
return 1;
}
next prev parent reply other threads:[~2019-10-31 15:38 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-22 20:34 [Patch v4 0/6] Introduce Thermal Pressure Thara Gopinath
2019-10-22 20:34 ` [Patch v4 1/6] sched/pelt.c: Add support to track thermal pressure Thara Gopinath
2019-10-31 9:47 ` Ionela Voinescu
2019-10-22 20:34 ` [Patch v4 2/6] sched: Add infrastructure to store and update instantaneous " Thara Gopinath
2019-10-28 15:21 ` Peter Zijlstra
2019-10-30 21:37 ` Thara Gopinath
2019-11-01 12:17 ` Dietmar Eggemann
2019-11-01 20:57 ` Thara Gopinath
2019-11-04 17:29 ` Dietmar Eggemann
2019-11-04 17:34 ` Vincent Guittot
2019-11-04 17:41 ` Dietmar Eggemann
2019-11-04 17:48 ` Vincent Guittot
2019-10-22 20:34 ` [Patch v4 3/6] sched/fair: Enable CFS periodic tick to update " Thara Gopinath
2019-10-28 15:24 ` Peter Zijlstra
2019-10-28 15:27 ` Peter Zijlstra
2019-10-30 21:41 ` Thara Gopinath
2019-10-31 16:11 ` Dietmar Eggemann
2019-10-31 16:46 ` Thara Gopinath
2019-10-22 20:34 ` [Patch v4 4/6] sched/fair: update cpu_capcity to reflect " Thara Gopinath
2019-10-23 12:28 ` Qais Yousef
2019-10-28 15:30 ` Peter Zijlstra
2019-10-31 10:53 ` Qais Yousef
2019-10-31 15:38 ` Dietmar Eggemann [this message]
2019-10-31 15:48 ` Vincent Guittot
2019-10-31 16:17 ` Dietmar Eggemann
2019-10-31 16:31 ` Vincent Guittot
2019-10-31 16:44 ` Dietmar Eggemann
2019-10-31 16:03 ` Thara Gopinath
2019-10-31 16:56 ` Qais Yousef
2019-10-22 20:34 ` [Patch v4 5/6] thermal/cpu-cooling: Update thermal pressure in case of a maximum frequency capping Thara Gopinath
2019-10-28 15:33 ` Peter Zijlstra
2019-10-31 16:29 ` Dietmar Eggemann
2019-10-31 16:38 ` Vincent Guittot
2019-11-01 15:47 ` Ionela Voinescu
2019-11-01 21:04 ` Thara Gopinath
2019-11-04 14:41 ` Ionela Voinescu
2019-10-31 16:46 ` Thara Gopinath
2019-10-22 20:34 ` [Patch v4 6/6] sched: thermal: Enable tuning of decay period Thara Gopinath
2019-10-28 15:42 ` Peter Zijlstra
2019-11-04 16:12 ` Ionela Voinescu
2019-11-05 20:26 ` Thara Gopinath
2019-11-05 21:29 ` Ionela Voinescu
2019-10-29 15:34 ` [Patch v4 0/6] Introduce Thermal Pressure Daniel Lezcano
2019-10-31 10:07 ` Ionela Voinescu
2019-10-31 11:54 ` Daniel Lezcano
2019-10-31 12:57 ` Ionela Voinescu
2019-10-31 17:48 ` Daniel Lezcano
2019-10-31 9:44 ` Ionela Voinescu
2019-10-31 16:41 ` Thara Gopinath
2019-10-31 16:52 ` Thara Gopinath
2019-11-05 21:04 ` Ionela Voinescu
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