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From: "Doug Smythies" <dsmythies@telus.net>
To: "'Qais Yousef'" <qais.yousef@arm.com>
Cc: "'Giovanni Gherdovich'" <ggherdovich@suse.cz>, <x86@kernel.org>,
	<linux-pm@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
	"'Mel Gorman'" <mgorman@techsingularity.net>,
	"'Matt Fleming'" <matt@codeblueprint.co.uk>,
	"'Viresh Kumar'" <viresh.kumar@linaro.org>,
	"'Juri Lelli'" <juri.lelli@redhat.com>,
	"'Paul Turner'" <pjt@google.com>,
	"'Peter Zijlstra'" <peterz@infradead.org>,
	"'Vincent Guittot'" <vincent.guittot@linaro.org>,
	"'Quentin Perret'" <qperret@qperret.net>,
	"'Dietmar Eggemann'" <dietmar.eggemann@arm.com>,
	"'Srinivas Pandruvada'" <srinivas.pandruvada@linux.intel.com>,
	"'Thomas Gleixner'" <tglx@linutronix.de>,
	"'Ingo Molnar'" <mingo@redhat.com>,
	"'Borislav Petkov'" <bp@suse.de>, "'Len Brown'" <lenb@kernel.org>,
	"'Rafael J . Wysocki'" <rjw@rjwysocki.net>
Subject: RE: [PATCH v4 1/6] x86,sched: Add support for frequency invariance
Date: Mon, 23 Dec 2019 17:16:39 -0800
Message-ID: <000401d5b9f7$cf3782c0$6da68840$@net> (raw)
In-Reply-To: <20191223191014.g7lnxafuadwtcqub@e107158-lin.cambridge.arm.com>

On 2019.12.23 11:10 Qais Yousef wrote:
> On 12/23/19 08:34, Doug Smythies wrote:
>> On 2019.12.23 06:41 Qais Yousef wrote:
>>> On 12/23/19 14:07, Qais Yousef wrote:
>>>>> Re-boot to the nocgv1 (stock + cgroup_no_v1=all) kernel.
>>>>> set the schedutil governor.
>>>>> launch test 2 and related monitoring tools.
>>>>> verify performance governor like behavior.
>>>> 
>>>> So as stated above, by default uclamp_{min, max} = (0, 1024). So it wouldn't
>>>> act as performance governor by default unless you explicitly write 1024 to
>>>> uclamp.min.
>>>> 
>>>> Let me go find Ubuntu mainline tree to see if they applied anything extra in
>>>> there. If they modified the default behavior that could explain what you see.
>>>
>>> Actually I see what you were saying now that you copy the config. So I think
>>>  I misunderstood and you are running Linus' 5.5-rc2 + Ubuntu PPA config.
>> 
>> Yes, exactly.
>> I have a clone of the main Linus git branch, but steal the kernel
>> configuration from the Ubuntu mainline PPA.
>
> I think I managed to reproduce it. The below seems to fix it for me, can you
> try it out please?

Yes, it fixes the schedutil governor behaving like the performance governor
problem on my i7-2600K test system.

I re-ran the tests several times, and re-booted back to the stock (problem)
kernel to verify incorrect schedutil governor performance (i.e. I toggled
back and forth, 2 times for each of 2 kernels, tests 1 and 2, total 8 tests).
Kernel 5.5-rc2: 4 tests FAILED (as expected).
Kernel 5.5-rc2 + this patch: 4 tests PASSED.

Accidentally tested:
Kernel 5.5-rc2 + this patch + command line "cgroup_no_v1=all": 1 test PASS.

> I think what's going on is that the child group default util_min value isn't
> propagated correctly after it's created, so we end up using the root_task_group
> values which is 1024 for both min and max.

O.K. thanks.

> ---
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index 90e4b00ace89..cf9d9106d1b5 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -7100,6 +7100,11 @@ static int cpu_cgroup_css_online(struct cgroup_subsys_state *css)
>
>        if (parent)
>                sched_online_group(tg, parent);
> +
> +#ifdef CONFIG_UCLAMP_TASK_GROUP
> +       cpu_util_update_eff(css);
> +#endif
> +
>        return 0;
>  }

... Doug



  reply index

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-13 12:46 [PATCH v4 0/6] Add support for frequency invariance for (some) x86 Giovanni Gherdovich
2019-11-13 12:46 ` [PATCH v4 1/6] x86,sched: Add support for frequency invariance Giovanni Gherdovich
2019-11-24  7:49   ` Doug Smythies
2019-11-25  8:16     ` Doug Smythies
2019-11-25  9:16     ` Mel Gorman
2019-11-25 16:06     ` Giovanni Gherdovich
2019-11-26  5:59       ` Doug Smythies
2019-11-26 15:20         ` Giovanni Gherdovich
2019-11-27  7:32           ` Doug Smythies
2019-11-28 22:48             ` Doug Smythies
2019-12-19 10:48               ` Qais Yousef
2019-12-23  7:47                 ` Doug Smythies
2019-12-23 14:07                   ` Qais Yousef
2019-12-23 14:40                     ` Qais Yousef
2019-12-23 16:34                       ` Doug Smythies
2019-12-23 19:10                         ` Qais Yousef
2019-12-24  1:16                           ` Doug Smythies [this message]
2019-12-24 11:08                             ` Qais Yousef
2019-12-02 16:34   ` Ionela Voinescu
2019-12-06 11:57     ` Giovanni Gherdovich
2019-12-18 19:34       ` Peter Zijlstra
2019-12-19 20:27         ` Giovanni Gherdovich
2019-11-13 12:46 ` [PATCH v4 2/6] x86,sched: Add support for frequency invariance on SKYLAKE_X Giovanni Gherdovich
2019-12-18 20:06   ` Peter Zijlstra
2019-12-19 20:29     ` Giovanni Gherdovich
2019-11-13 12:46 ` [PATCH v4 3/6] x86,sched: Add support for frequency invariance on XEON_PHI_KNL/KNM Giovanni Gherdovich
2019-12-18 20:22   ` Peter Zijlstra
2019-12-19 20:32     ` Giovanni Gherdovich
2019-11-13 12:46 ` [PATCH v4 4/6] x86,sched: Add support for frequency invariance on ATOM_GOLDMONT* Giovanni Gherdovich
2019-11-13 12:46 ` [PATCH v4 5/6] x86,sched: Add support for frequency invariance on ATOM Giovanni Gherdovich
2019-11-13 16:50   ` Srinivas Pandruvada
2019-11-15 10:34     ` Giovanni Gherdovich
2019-11-13 12:46 ` [PATCH v4 6/6] x86: intel_pstate: handle runtime turbo disablement/enablement in freq. invariance Giovanni Gherdovich
2019-12-18 20:37 ` [PATCH v4 0/6] Add support for frequency invariance for (some) x86 Peter Zijlstra
2019-12-19 20:33   ` Giovanni Gherdovich

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