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From: Qais Yousef <qais.yousef@arm.com>
To: Doug Smythies <dsmythies@telus.net>
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: Tue, 24 Dec 2019 11:08:35 +0000
Message-ID: <20191224110834.rgibtqm6dr6kmu5y@e107158-lin.cambridge.arm.com> (raw)
In-Reply-To: <000401d5b9f7$cf3782c0$6da68840$@net>

On 12/23/19 17:16, Doug Smythies wrote:
> 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.

Great! Thanks for testing it, I'll send a proper patch shortly.

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

I think this cgroup_no_v1 is a happy accident. It has nothing to do with the
fault, but for your case maybe helped observing things in a better way. FWIW,
I reproduced the issue on Juno Arm64 using Debian and Buildroot rootfs.

What is actually required to trigger the bug is to create a cpu controller and
add all system tasks to it to create some noise - which Ubuntu and Debian do by
default at boot time. In Buildroot when I did that manually I could see the
frequency going to max most of the time.

I'll add away to test this scenario.

Thanks for your detailed report.

Happy holidays!

--
Qais Yousef

  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
2019-12-24 11:08                             ` Qais Yousef [this message]
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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