diff options
| author | Dietmar Eggemann <dietmar.eggemann@arm.com> | 2019-01-28 16:55:21 +0000 |
|---|---|---|
| committer | Sudeep Holla <sudeep.holla@arm.com> | 2019-01-29 15:31:37 +0000 |
| commit | 4daa001a17739947bf966e388e8a287db80d478b (patch) | |
| tree | e3f549a50feaaffbe90e377cccd6c68189e9797e /arch/arm64/boot/dts/arm/juno.dts | |
| parent | fa083b99eb284186ae65193ae856ef2801a1646d (diff) | |
arm64: dts: juno: Add cpu dynamic-power-coefficient information
A CPUfreq driver, like the scpi driver used on Juno boards, which
provide the Energy Model with power cost information via the PM_OPP
of_dev_pm_opp_get_cpu_power() function, do need the
dynamic-power-coefficient (C) in the device tree.
Method used to obtain the C value:
C is computed by measuring energy (E) consumption of a frequency domain
(FD) over a 10s runtime (t) sysbench workload running at each Operating
Performance Point (OPP) affine to 1 or 2 CPUs of that FD while the other
CPUs of the system are hotplugged out.
By definition all CPUs of a FD have the the same micro-architecture. An
OPP is characterized by a certain frequency (f) and voltage (V) value.
The corresponding power values (P) are calculated by dividing the delta
of the E values between the runs with 2 and 1 CPUs by t.
With n data tuples (P, f, V), n equal to number of OPPs for this
frequency domain, we can solve C by:
P = Pstat + Pdyn
P = Pstat + CV²f
Cx = (Px - P1)/(Vx²fx - V1²f1) with x = {2, ..., n}
The C value is the arithmetic mean out of {C2, ..., Cn}.
Since DVFS is broken on Juno r1, no dynamic-power-coefficient
information has been added to its dts file.
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Quentin Perret <quentin.perret@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Diffstat (limited to 'arch/arm64/boot/dts/arm/juno.dts')
| -rw-r--r-- | arch/arm64/boot/dts/arm/juno.dts | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/arch/arm64/boot/dts/arm/juno.dts b/arch/arm64/boot/dts/arm/juno.dts index 08d4ba1716c3..9890afdda77b 100644 --- a/arch/arm64/boot/dts/arm/juno.dts +++ b/arch/arm64/boot/dts/arm/juno.dts @@ -98,6 +98,7 @@ clocks = <&scpi_dvfs 0>; cpu-idle-states = <&CPU_SLEEP_0 &CLUSTER_SLEEP_0>; capacity-dmips-mhz = <1024>; + dynamic-power-coefficient = <530>; }; A57_1: cpu@1 { @@ -115,6 +116,7 @@ clocks = <&scpi_dvfs 0>; cpu-idle-states = <&CPU_SLEEP_0 &CLUSTER_SLEEP_0>; capacity-dmips-mhz = <1024>; + dynamic-power-coefficient = <530>; }; A53_0: cpu@100 { @@ -132,6 +134,7 @@ clocks = <&scpi_dvfs 1>; cpu-idle-states = <&CPU_SLEEP_0 &CLUSTER_SLEEP_0>; capacity-dmips-mhz = <578>; + dynamic-power-coefficient = <140>; }; A53_1: cpu@101 { @@ -149,6 +152,7 @@ clocks = <&scpi_dvfs 1>; cpu-idle-states = <&CPU_SLEEP_0 &CLUSTER_SLEEP_0>; capacity-dmips-mhz = <578>; + dynamic-power-coefficient = <140>; }; A53_2: cpu@102 { @@ -166,6 +170,7 @@ clocks = <&scpi_dvfs 1>; cpu-idle-states = <&CPU_SLEEP_0 &CLUSTER_SLEEP_0>; capacity-dmips-mhz = <578>; + dynamic-power-coefficient = <140>; }; A53_3: cpu@103 { @@ -183,6 +188,7 @@ clocks = <&scpi_dvfs 1>; cpu-idle-states = <&CPU_SLEEP_0 &CLUSTER_SLEEP_0>; capacity-dmips-mhz = <578>; + dynamic-power-coefficient = <140>; }; A57_L2: l2-cache0 { |