From: Dietmar Eggemann <dietmar.eggemann@arm.com>
To: Peter Zijlstra <peterz@infradead.org>,
Thara Gopinath <thara.gopinath@linaro.org>
Cc: Randy Dunlap <rdunlap@infradead.org>,
mingo@redhat.com, ionela.voinescu@arm.com,
vincent.guittot@linaro.org, rui.zhang@intel.com,
qperret@google.com, daniel.lezcano@linaro.org,
viresh.kumar@linaro.org, rostedt@goodmis.org, will@kernel.org,
catalin.marinas@arm.com, sudeep.holla@arm.com,
juri.lelli@redhat.com, corbet@lwn.net,
linux-kernel@vger.kernel.org, amit.kachhap@gmail.com,
javi.merino@kernel.org, amit.kucheria@verdurent.com
Subject: Re: [Patch v9 7/8] sched/fair: Enable tuning of decay period
Date: Tue, 4 Feb 2020 09:39:12 +0100 [thread overview]
Message-ID: <cc83634f-b3af-6024-7f89-9b231b153070@arm.com> (raw)
In-Reply-To: <20200203155549.GL14914@hirez.programming.kicks-ass.net>
On 03/02/2020 16:55, Peter Zijlstra wrote:
> On Mon, Feb 03, 2020 at 07:07:57AM -0500, Thara Gopinath wrote:
>> On 01/28/2020 06:56 PM, Randy Dunlap wrote:
>>> Hi,
>>>
>>> On 1/28/20 2:36 PM, Thara Gopinath wrote:
>>>> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
>>>> index e35b28e..be4147b 100644
>>>> --- a/Documentation/admin-guide/kernel-parameters.txt
>>>> +++ b/Documentation/admin-guide/kernel-parameters.txt
>>>> @@ -4376,6 +4376,11 @@
>>>> incurs a small amount of overhead in the scheduler
>>>> but is useful for debugging and performance tuning.
>>>>
>>>> + sched_thermal_decay_shift=
>>>> + [KNL, SMP] Set decay shift for thermal pressure signal.
>>>> + Format: integer between 0 and 10
>>>> + Default is 0.
>>>> +
>>>
>>> That tells an admin [or any reader] almost nothing about this kernel parameter
>>> or what it does. And nothing about what unit the value is in.
>>> Does the value 0 disable this feature?
>>
>> Thanks for the review. 0 does not disable "thermal pressure" feature. 0
>> means the default decay period for averaging PELT signals (which is
>> usually 32 but configurable) will also be applied for thermal pressure
>> signal. A shift will shift the default decay period.
>>
>> You are right. It needs more explanation here. I will fix it and send v10.
>
> Or just send an update for this patch? I'm thinking most of this is
> looking good.
I do agree. IMHO, there are just two little things outstanding:
(1) arch_scale_thermal_pressure() instead of
arch_cpu_thermal_pressure() in v8 4/7
(2) guarding of thermal pressure code in Arm's arch_topology driver w/
CONFIG_HAVE_SCHED_THERMAL_PRESSURE plus disabling it by default for
Arm64.
next prev parent reply other threads:[~2020-02-04 8:39 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-28 22:35 [Patch v9 0/8] Introduce Thermal Pressure Thara Gopinath
2020-01-28 22:36 ` [Patch v9 1/8] sched/pelt: Add support to track thermal pressure Thara Gopinath
2020-02-13 12:29 ` Amit Kucheria
2020-02-13 14:11 ` Thara Gopinath
2020-02-13 14:41 ` Amit Kucheria
2020-01-28 22:36 ` [Patch v9 2/8] sched/topology: Add hook to read per cpu " Thara Gopinath
2020-01-28 22:36 ` [Patch v9 3/8] arm,arm64,drivers:Add infrastructure to store and update instantaneous " Thara Gopinath
2020-02-13 12:25 ` Amit Kucheria
2020-02-13 14:05 ` Thara Gopinath
2020-02-13 14:38 ` Amit Kucheria
2020-02-14 15:01 ` Thara Gopinath
2020-01-28 22:36 ` [Patch v9 4/8] sched/fair: Enable periodic update of average " Thara Gopinath
2020-01-28 22:36 ` [Patch v9 5/8] sched/fair: update cpu_capacity to reflect " Thara Gopinath
2020-02-13 12:47 ` Amit Kucheria
2020-02-13 14:12 ` Thara Gopinath
2020-02-13 13:39 ` Amit Kucheria
2020-02-14 14:52 ` Thara Gopinath
2020-01-28 22:36 ` [Patch v9 6/8] thermal/cpu-cooling: Update thermal pressure in case of a maximum frequency capping Thara Gopinath
2020-01-28 22:36 ` [Patch v9 7/8] sched/fair: Enable tuning of decay period Thara Gopinath
2020-01-28 23:56 ` Randy Dunlap
2020-02-03 12:07 ` Thara Gopinath
2020-02-03 15:55 ` Peter Zijlstra
2020-02-04 8:39 ` Dietmar Eggemann [this message]
2020-02-07 22:42 ` Thara Gopinath
2020-02-10 11:59 ` Dietmar Eggemann
2020-02-13 13:54 ` Thara Gopinath
2020-02-14 10:26 ` Dietmar Eggemann
2020-02-18 14:57 ` Thara Gopinath
2020-02-19 9:14 ` Dietmar Eggemann
2020-01-28 22:36 ` [Patch v9 8/8] arm64: Enable averaging of thermal pressure for arm64 based SoCs Thara Gopinath
2020-02-03 8:59 ` Dietmar Eggemann
2020-02-10 12:07 ` [Patch v9 0/8] Introduce Thermal Pressure Dietmar Eggemann
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