From: Vincent Guittot vincent.guittot@linaro.org
[ Upstream commit 44750f153699b6e4f851a399287e5c8df208d696 ]
While stressing EAS on my dragonboard RB3, I have noticed that LITTLE cores where never selected as the most energy efficient CPU whatever the utilization level of waking task.
energy model framework uses its cost field to estimate the energy with the formula:
nrg = cost of the selected OPP * utilization / CPU's max capacity
which ends up selecting the CPU with lowest cost / max capacity ration as long as the utilization fits in the OPP's capacity.
If we compare the cost of a little OPP with similar capacity of a big OPP like : OPP(kHz) OPP capacity cost max capacity cost/max capacity LITTLE 1766400 407 351114 407 863 big 1056000 408 520267 1024 508
This can be interpreted as the LITTLE core consumes 70% more than big core for the same compute capacity.
According to [1], LITTLE consumes 10% less than big core for Coremark benchmark at those OPPs. If we consider that everything else stays unchanged, the dynamic-power-coefficient of LITTLE core should be only 53% of the current value: 290 * 53% = 154
Set the dynamic-power-coefficient of CPU0-3 to 154 to fix the energy model.
[1] https://github.com/kdrag0n/freqbench/tree/master/results/sdm845/main
Fixes: 0e0a8e35d725 ("arm64: dts: qcom: sdm845: correct dynamic power coefficients") Signed-off-by: Vincent Guittot vincent.guittot@linaro.org Signed-off-by: Bjorn Andersson andersson@kernel.org Link: https://lore.kernel.org/r/20230106164618.1845281-1-vincent.guittot@linaro.or... Signed-off-by: Sasha Levin sashal@kernel.org --- arch/arm64/boot/dts/qcom/sdm845.dtsi | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/arch/arm64/boot/dts/qcom/sdm845.dtsi b/arch/arm64/boot/dts/qcom/sdm845.dtsi index f36c23e7a2248..ed525397d2335 100644 --- a/arch/arm64/boot/dts/qcom/sdm845.dtsi +++ b/arch/arm64/boot/dts/qcom/sdm845.dtsi @@ -198,7 +198,7 @@ reg = <0x0 0x0>; enable-method = "psci"; capacity-dmips-mhz = <611>; - dynamic-power-coefficient = <290>; + dynamic-power-coefficient = <154>; qcom,freq-domain = <&cpufreq_hw 0>; operating-points-v2 = <&cpu0_opp_table>; interconnects = <&gladiator_noc MASTER_APPSS_PROC 3 &mem_noc SLAVE_EBI1 3>, @@ -222,7 +222,7 @@ reg = <0x0 0x100>; enable-method = "psci"; capacity-dmips-mhz = <611>; - dynamic-power-coefficient = <290>; + dynamic-power-coefficient = <154>; qcom,freq-domain = <&cpufreq_hw 0>; operating-points-v2 = <&cpu0_opp_table>; interconnects = <&gladiator_noc MASTER_APPSS_PROC 3 &mem_noc SLAVE_EBI1 3>, @@ -243,7 +243,7 @@ reg = <0x0 0x200>; enable-method = "psci"; capacity-dmips-mhz = <611>; - dynamic-power-coefficient = <290>; + dynamic-power-coefficient = <154>; qcom,freq-domain = <&cpufreq_hw 0>; operating-points-v2 = <&cpu0_opp_table>; interconnects = <&gladiator_noc MASTER_APPSS_PROC 3 &mem_noc SLAVE_EBI1 3>, @@ -264,7 +264,7 @@ reg = <0x0 0x300>; enable-method = "psci"; capacity-dmips-mhz = <611>; - dynamic-power-coefficient = <290>; + dynamic-power-coefficient = <154>; qcom,freq-domain = <&cpufreq_hw 0>; operating-points-v2 = <&cpu0_opp_table>; interconnects = <&gladiator_noc MASTER_APPSS_PROC 3 &mem_noc SLAVE_EBI1 3>,