This is a note to let you know that I've just added the patch titled
arm64: dts: qcom: sm8250: correct dynamic power coefficients
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
arm64-dts-qcom-sm8250-correct-dynamic-power-coeffici.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 52f17399243f5c6f0327001cc77b2c8bfe02ed44
Author: Vincent Guittot <vincent.guittot@xxxxxxxxxx>
Date: Thu Jun 15 17:48:52 2023 +0200
arm64: dts: qcom: sm8250: correct dynamic power coefficients
[ Upstream commit 775a5283c25d160b2a1359018c447bc518096547 ]
sm8250 faces the same problem with its Energy Model as sdm845. The energy
cost of LITTLE cores is reported to be higher than medium or big cores
EM computes the energy with formula:
energy = OPP's cost / maximum cpu capacity * utilization
On v6.4-rc6 we have:
max capacity of CPU0 = 284
capacity of CPU0's OPP(1612800 Hz) = 253
cost of CPU0's OPP(1612800 Hz) = 191704
max capacity of CPU4 = 871
capacity of CPU4's OPP(710400 Hz) = 255
cost of CPU4's OPP(710400 Hz) = 343217
Both OPPs have almost the same compute capacity but the estimated energy
per unit of utilization will be estimated to:
energy CPU0 = 191704 / 284 * 1 = 675
energy CPU4 = 343217 / 871 * 1 = 394
EM estimates that little CPU0 will consume 71% more than medium CPU4 for
the same compute capacity. According to [1], little consumes 25% less than
medium core for Coremark benchmark at those OPPs for the same duration.
Set the dynamic-power-coefficient of CPU0-3 to 105 to fix the energy model
for little CPUs.
[1] https://github.com/kdrag0n/freqbench/tree/master/results/sm8250/k30s
Fixes: 6aabed5526ee ("arm64: dts: qcom: sm8250: Add CPU capacities and energy model")
Signed-off-by: Vincent Guittot <vincent.guittot@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230615154852.130076-1-vincent.guittot@xxxxxxxxxx
Signed-off-by: Bjorn Andersson <andersson@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/arm64/boot/dts/qcom/sm8250.dtsi b/arch/arm64/boot/dts/qcom/sm8250.dtsi
index 181e32b8a2728..005e75dc6919e 100644
--- a/arch/arm64/boot/dts/qcom/sm8250.dtsi
+++ b/arch/arm64/boot/dts/qcom/sm8250.dtsi
@@ -97,7 +97,7 @@ CPU0: cpu@0 {
reg = <0x0 0x0>;
enable-method = "psci";
capacity-dmips-mhz = <448>;
- dynamic-power-coefficient = <205>;
+ dynamic-power-coefficient = <105>;
next-level-cache = <&L2_0>;
qcom,freq-domain = <&cpufreq_hw 0>;
#cooling-cells = <2>;
@@ -116,7 +116,7 @@ CPU1: cpu@100 {
reg = <0x0 0x100>;
enable-method = "psci";
capacity-dmips-mhz = <448>;
- dynamic-power-coefficient = <205>;
+ dynamic-power-coefficient = <105>;
next-level-cache = <&L2_100>;
qcom,freq-domain = <&cpufreq_hw 0>;
#cooling-cells = <2>;
@@ -132,7 +132,7 @@ CPU2: cpu@200 {
reg = <0x0 0x200>;
enable-method = "psci";
capacity-dmips-mhz = <448>;
- dynamic-power-coefficient = <205>;
+ dynamic-power-coefficient = <105>;
next-level-cache = <&L2_200>;
qcom,freq-domain = <&cpufreq_hw 0>;
#cooling-cells = <2>;
@@ -148,7 +148,7 @@ CPU3: cpu@300 {
reg = <0x0 0x300>;
enable-method = "psci";
capacity-dmips-mhz = <448>;
- dynamic-power-coefficient = <205>;
+ dynamic-power-coefficient = <105>;
next-level-cache = <&L2_300>;
qcom,freq-domain = <&cpufreq_hw 0>;
#cooling-cells = <2>;
