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Date:   Tue, 12 Jan 2021 17:59:47 +0300
From:   Alexey Minnekhanov <alexey.min@...il.com>
To:     Danny Lin <danny@...ag0n.dev>
Cc:     Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Alexey Minekhanov <alexeymin@...tmarketos.org>
Subject: Re: [PATCH] arm64: dts: qcom: sdm660: Fix CPU capacities

Hi!
I always had a feeling something is not right in those cpu
definitions, so cpus with reg 100-103 are little cores, and 0-3 big
ones?
But downstream sdm660.dtsi has a property "efficiency" [1] with values
which are larger for cores 100-103 than for 0-3 cores (1638 > 1024),
I'm confused...

Property "efficiency" is described in the same tree in [2].

[1] https://source.codeaurora.org/quic/la/kernel/msm-4.4/tree/arch/arm/boot/dts/qcom/sdm660.dtsi?h=LA.UM.7.2.c25#n155
[2] https://source.codeaurora.org/quic/la/kernel/msm-4.4/tree/Documentation/devicetree/bindings/arm/cpus.txt?h=LA.UM.7.2.c25#n216

вт, 12 янв. 2021 г. в 13:51, Danny Lin <danny@...ag0n.dev>:
>
> sdm660 has a big.LITTLE 4+4 CPU setup with CPUs 0-3 being little cores
> and CPUs 4-7 being big cores. The big cores have higher IPC, so they
> should have the higher capacity-dmips-mhz, not the other way around as
> the device tree currently describes it. Fix the incorrect CPU map to
> improve EAS scheduling behavior.
>
> While we're at it, let's replace the old DMIPS/MHz values with new
> measurements that reflect the exact IPC of the CPUs as reported by
> CoreMark.
>
> Performance measurements were made using my freqbench [1]
> benchmark coordinator, which isolates, offlines, and disables the timer
> tick on test CPUs to maximize accuracy. It uses EEMBC CoreMark [2] as
> the workload and measures power usage using the PM660 PMIC's fuel
> gauge.
>
> Normalized DMIPS/MHz capacity scale values for each CPU were calculated
> from CoreMarks/MHz (CoreMark iterations per second per MHz), which
> serves the same purpose. For each CPU, the final capacity-dmips-mhz
> value is the C/MHz value of its maximum frequency normalized to
> SCHED_CAPACITY_SCALE (1024) for the fastest CPU in the system.
>
> A Xiaomi Redmi Note 7 device running a downstream Qualcomm 4.4 kernel
> was used for benchmarking to ensure proper frequency scaling and other
> low-level controls.
>
> Raw benchmark results can be found in the freqbench repository [3].
> Below is a human-readable summary:
>
> Frequency domains: cpu1 cpu4
> Offline CPUs: cpu1 cpu2 cpu3 cpu4 cpu5 cpu6 cpu7
> Baseline power usage: 1130 mW
>
> ===== CPU 1 =====
> Frequencies: 633 902 1113 1401 1536 1747 1843
>
>  633:  2058     3.2 C/MHz     48 mW    5.9 J   42.6 I/mJ   121.5 s
>  902:  2930     3.2 C/MHz     72 mW    6.2 J   40.6 I/mJ    85.3 s
> 1113:  3616     3.2 C/MHz     79 mW    5.4 J   46.0 I/mJ    69.1 s
> 1401:  4551     3.2 C/MHz    125 mW    6.9 J   36.3 I/mJ    54.9 s
> 1536:  4988     3.2 C/MHz    134 mW    6.7 J   37.1 I/mJ    50.1 s
> 1747:  5674     3.2 C/MHz    179 mW    7.9 J   31.7 I/mJ    44.1 s
> 1843:  5986     3.2 C/MHz    228 mW    9.5 J   26.3 I/mJ    41.8 s
>
> ===== CPU 4 =====
> Frequencies: 1113 1401 1747 1958 2150 2208
>
> 1113:  5825     5.2 C/MHz    220 mW    9.4 J   26.5 I/mJ    42.9 s
> 1401:  7324     5.2 C/MHz    317 mW   10.8 J   23.1 I/mJ    34.1 s
> 1747:  9135     5.2 C/MHz    474 mW   13.0 J   19.2 I/mJ    27.4 s
> 1958: 10247     5.2 C/MHz    578 mW   14.1 J   17.7 I/mJ    24.4 s
> 2150: 11246     5.2 C/MHz    694 mW   15.4 J   16.2 I/mJ    22.2 s
> 2208: 11551     5.2 C/MHz    736 mW   15.9 J   15.7 I/mJ    21.7 s
>
> [1] https://github.com/kdrag0n/freqbench
> [2] https://www.eembc.org/coremark/
> [3] https://github.com/kdrag0n/freqbench/tree/master/results/sdm660/main
>
> Signed-off-by: Danny Lin <danny@...ag0n.dev>
> ---
>  arch/arm64/boot/dts/qcom/sdm660.dtsi | 16 ++++++++--------
>  1 file changed, 8 insertions(+), 8 deletions(-)
>
> diff --git a/arch/arm64/boot/dts/qcom/sdm660.dtsi b/arch/arm64/boot/dts/qcom/sdm660.dtsi
> index 4abbdd03d1e7..ca985c5429db 100644
> --- a/arch/arm64/boot/dts/qcom/sdm660.dtsi
> +++ b/arch/arm64/boot/dts/qcom/sdm660.dtsi
> @@ -40,7 +40,7 @@ CPU0: cpu@100 {
>                         compatible = "qcom,kryo260";
>                         reg = <0x0 0x100>;
>                         enable-method = "psci";
> -                       capacity-dmips-mhz = <1024>;
> +                       capacity-dmips-mhz = <636>;
>                         next-level-cache = <&L2_1>;
>                         L2_1: l2-cache {
>                                 compatible = "cache";
> @@ -59,7 +59,7 @@ CPU1: cpu@101 {
>                         compatible = "qcom,kryo260";
>                         reg = <0x0 0x101>;
>                         enable-method = "psci";
> -                       capacity-dmips-mhz = <1024>;
> +                       capacity-dmips-mhz = <636>;
>                         next-level-cache = <&L2_1>;
>                         L1_I_101: l1-icache {
>                                 compatible = "cache";
> @@ -74,7 +74,7 @@ CPU2: cpu@102 {
>                         compatible = "qcom,kryo260";
>                         reg = <0x0 0x102>;
>                         enable-method = "psci";
> -                       capacity-dmips-mhz = <1024>;
> +                       capacity-dmips-mhz = <636>;
>                         next-level-cache = <&L2_1>;
>                         L1_I_102: l1-icache {
>                                 compatible = "cache";
> @@ -89,7 +89,7 @@ CPU3: cpu@103 {
>                         compatible = "qcom,kryo260";
>                         reg = <0x0 0x103>;
>                         enable-method = "psci";
> -                       capacity-dmips-mhz = <1024>;
> +                       capacity-dmips-mhz = <636>;
>                         next-level-cache = <&L2_1>;
>                         L1_I_103: l1-icache {
>                                 compatible = "cache";
> @@ -104,7 +104,7 @@ CPU4: cpu@0 {
>                         compatible = "qcom,kryo260";
>                         reg = <0x0 0x0>;
>                         enable-method = "psci";
> -                       capacity-dmips-mhz = <640>;
> +                       capacity-dmips-mhz = <1024>;
>                         next-level-cache = <&L2_0>;
>                         L2_0: l2-cache {
>                                 compatible = "cache";
> @@ -123,7 +123,7 @@ CPU5: cpu@1 {
>                         compatible = "qcom,kryo260";
>                         reg = <0x0 0x1>;
>                         enable-method = "psci";
> -                       capacity-dmips-mhz = <640>;
> +                       capacity-dmips-mhz = <1024>;
>                         next-level-cache = <&L2_0>;
>                         L1_I_1: l1-icache {
>                                 compatible = "cache";
> @@ -138,7 +138,7 @@ CPU6: cpu@2 {
>                         compatible = "qcom,kryo260";
>                         reg = <0x0 0x2>;
>                         enable-method = "psci";
> -                       capacity-dmips-mhz = <640>;
> +                       capacity-dmips-mhz = <1024>;
>                         next-level-cache = <&L2_0>;
>                         L1_I_2: l1-icache {
>                                 compatible = "cache";
> @@ -153,7 +153,7 @@ CPU7: cpu@3 {
>                         compatible = "qcom,kryo260";
>                         reg = <0x0 0x3>;
>                         enable-method = "psci";
> -                       capacity-dmips-mhz = <640>;
> +                       capacity-dmips-mhz = <1024>;
>                         next-level-cache = <&L2_0>;
>                         L1_I_3: l1-icache {
>                                 compatible = "cache";
> --
> 2.29.2
>

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