On Wed, Apr 02, 2025 at 02:59:31PM -0700, William McVicker wrote: > 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 <willdeacon@xxxxxxxxxx> > > > > > > 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 <willdeacon@xxxxxxxxxx> > > > [Original commit from https://android.googlesource.com/kernel/gs/+/a896fd98638047989513d05556faebd28a62b27c] > > > Signed-off-by: Will McVicker <willmcvicker@xxxxxxxxxx> > > > --- > > > 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@xxxxxxxxxxxxxx/ > [2] https://lore.kernel.org/linux-samsung-soc/CAASgrz2Nr69tpfC8ka9gbs2OvjLEGsvgAj4vBCFxhsamuFum7w@xxxxxxxxxxxxxx/ > > 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 > > [...] > Hi Will, Thanks for sharing the status of Pixel devices. I agree that using the arch_timer as a clock source device brings significant benefits. The links you shared are definitely related to that. However, I would also like to know whether arch_timer is used as a clock event device in Pixel production. Thanks, Youngmin
