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[35.247.103.198]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-229785c2791sm636175ad.80.2025.04.02.14.59.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 02 Apr 2025 14:59:35 -0700 (PDT) Date: Wed, 2 Apr 2025 14:59:31 -0700 From: William McVicker To: Youngmin Nam Cc: Catalin Marinas , Will Deacon , Peter Griffin , =?iso-8859-1?Q?Andr=E9?= Draszik , Tudor Ambarus , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Alim Akhtar , Daniel Lezcano , Thomas Gleixner , Saravana Kannan , kernel-team@android.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-samsung-soc@vger.kernel.org, devicetree@vger.kernel.org, Will Deacon Subject: Re: [PATCH v1 4/6] arm64: dts: exynos: gs101: Add 'local-timer-stop' to cpuidle nodes Message-ID: References: <20250331230034.806124-1-willmcvicker@google.com> <20250331230034.806124-5-willmcvicker@google.com> 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=us-ascii Content-Disposition: inline In-Reply-To: Hi Youngmin, On 04/02/2025, Youngmin Nam wrote: > On Mon, Mar 31, 2025 at 04:00:26PM -0700, Will McVicker wrote: > > From: Will Deacon > > > > In preparation for switching to the architected timer as the primary > > clockevents device, mark the cpuidle nodes with the 'local-timer-stop' > > property to indicate that an alternative clockevents device must be > > used for waking up from the "c2" idle state. > > > > Signed-off-by: Will Deacon > > [Original commit from https://android.googlesource.com/kernel/gs/+/a896fd98638047989513d05556faebd28a62b27c] > > Signed-off-by: Will McVicker > > --- > > arch/arm64/boot/dts/exynos/google/gs101.dtsi | 3 +++ > > 1 file changed, 3 insertions(+) > > > > diff --git a/arch/arm64/boot/dts/exynos/google/gs101.dtsi b/arch/arm64/boot/dts/exynos/google/gs101.dtsi > > index 3de3a758f113..fd0badf24e6f 100644 > > --- a/arch/arm64/boot/dts/exynos/google/gs101.dtsi > > +++ b/arch/arm64/boot/dts/exynos/google/gs101.dtsi > > @@ -155,6 +155,7 @@ ananke_cpu_sleep: cpu-ananke-sleep { > > idle-state-name = "c2"; > > compatible = "arm,idle-state"; > > arm,psci-suspend-param = <0x0010000>; > > + local-timer-stop; > > entry-latency-us = <70>; > > exit-latency-us = <160>; > > min-residency-us = <2000>; > > @@ -164,6 +165,7 @@ enyo_cpu_sleep: cpu-enyo-sleep { > > idle-state-name = "c2"; > > compatible = "arm,idle-state"; > > arm,psci-suspend-param = <0x0010000>; > > + local-timer-stop; > > entry-latency-us = <150>; > > exit-latency-us = <190>; > > min-residency-us = <2500>; > > @@ -173,6 +175,7 @@ hera_cpu_sleep: cpu-hera-sleep { > > idle-state-name = "c2"; > > compatible = "arm,idle-state"; > > arm,psci-suspend-param = <0x0010000>; > > + local-timer-stop; > > entry-latency-us = <235>; > > exit-latency-us = <220>; > > min-residency-us = <3500>; > > -- > > 2.49.0.472.ge94155a9ec-goog > > > Hi Will. > > Are you using this property in production? > If so, have you noticed any performance improvements? On Pixel 6, I have only recently switched to using the arch_timer as the default clocksource. I haven't noticed any major perf improvements to the main benchmarks, but also haven't seen any regressions. Based on the ChromeOS perf analysis in [1,2], there was a significant perf difference found. [1] https://lore.kernel.org/linux-samsung-soc/CAJFHJrrgWGc4XGQB0ysLufAg3Wouz-aYXu97Sy2Kp=HzK+akVQ@mail.gmail.com/ [2] https://lore.kernel.org/linux-samsung-soc/CAASgrz2Nr69tpfC8ka9gbs2OvjLEGsvgAj4vBCFxhsamuFum7w@mail.gmail.com/ If it helps, I found that Pixel 8 and 9 devices (didn't check Pixel 7) are already using the arch_timer with this 'local-timer-stop' as the default clocksource in the production kernel. Thanks, Will [...]