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[66.183.142.209]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-7a23010e24fsm11510899b3a.57.2025.10.21.07.30.16 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Tue, 21 Oct 2025 07:30:17 -0700 (PDT) From: "Doug Smythies" To: "'Sergey Senozhatsky'" Cc: "'Rafael J. Wysocki'" , "'Christian Loehle'" , "'Linux PM'" , "'LKML'" , "'Artem Bityutskiy'" , "'Tomasz Figa'" , "Doug Smythies" References: <4687373.LvFx2qVVIh@rafael.j.wysocki> <5f0aa630-b30a-44c4-a52c-e08179cd3bf9@arm.com> <28ecb23b-ecee-409a-9771-24f801081d07@arm.com> <001801dc4041$607c19f0$21744dd0$@telus.net> In-Reply-To: Subject: RE: [PATCH v1] cpuidle: governors: menu: Predict longer idle time when in doubt Date: Tue, 21 Oct 2025 07:30:17 -0700 Message-ID: <001201dc4297$3903af70$ab0b0e50$@telus.net> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Mailer: Microsoft Outlook 16.0 Thread-Index: AQEHjVQKCrlPynWgLAaVpIarC+pGJQGZtDQKAi3SGCUCWYi7hgLZuqUGAZPsdfIBj3Y3ebYVH1IA Content-Language: en-ca On 2025.10.20 20:43 Sergey Senozhatsky wrote: > On (25/10/18 08:10), Doug Smythies wrote: >> On 2025.10.18 04:47 Rafael wrote: >>> On Fri, Oct 17, 2025 at 8:37=E2=80=AFPM Christian Loehle wrote: >>>> On 10/17/25 10:39, Rafael J. Wysocki wrote: >>>>> On Fri, Oct 17, 2025 at 10:22=E2=80=AFAM Christian Loehle wrote: >>>>>> On 10/16/25 17:25, Rafael J. Wysocki wrote: >>>>>>> From: Rafael J. Wysocki >>>>>>> >>>>>>> It is reported that commit 85975daeaa4d ("cpuidle: menu: Avoid = discarding >>>>>>> useful information") led to a performance regression on Intel = Jasper Lake >>>>>>> systems because it reduced the time spent by CPUs in idle state = C7 which >>>>>>> is correlated to the maximum frequency the CPUs can get to = because of an >>>>>>> average running power limit [1]. >>=20 >> I would like to understand Sergey's benchmark test better, and even = try >> to repeat the results on my test system. I would also like to try to=20 >> separate the variables in an attempt to isolate potential = contributors. >>=20 >> To eliminate the PL1 effect, limit the CPU frequency to 2300 MHz and = repeat >> the test. To eliminate potential CPU frequency scaling contributions, = use the >> performance CPU frequency scaling governor. Both changes at once = would >> be an acceptable first step. >>=20 >> Sergey: Would you be willing to do that test? > > Apologies for the delay. > > Sure, I can give it a try sometime this week, am dealing with a bunch > of other stable regressions right now (will report separately). > > Can you please help me with the configuration steps? CPU freq = limiting, > etc. For your system booted with "base" and "revert" do: echo performance | sudo tee = /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor echo 2300000 | sudo tee = /sys/devices/system/cpu/cpufreq/policy*/scaling_max_freq then do your test. > >> Sergey: Could you provide more details about your test? > > We track regressions in a number of tests. The one I'm running more > often than others is a Google Docs test (our tests replicate real use > cases). The test in question creates new google docs (in chrome, of > course) and inputs some text in them (with various words-per-minute > settings - 60, 90, 120 wpm) in English, Japanese, Korean and other > languages; different font faces, different styles (bold, italic), > text highlighting/selection, windows switching, and so on. The test > measures input latency, the number of dropped frames during scrolling, > CPU usage, power consumption, etc. Okay, Thanks. So not a test I can repeat on my test computer. ... Doug