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| author | Dietmar Eggemann <dietmar.eggemann@arm.com> | 2019-01-28 19:55:22 +0300 |
|---|---|---|
| committer | Sudeep Holla <sudeep.holla@arm.com> | 2019-01-29 18:30:00 +0300 |
| commit | cc0dbf43668db407692deaf2023d4adbeeef9633 (patch) | |
| tree | 459d3366a3d62a422a79350421da4f06e55a10c6 /arch/arm/boot/dts | |
| parent | 01980aa7b0d7fde864899787510ddc01c1657c9a (diff) | |
| download | linux-cc0dbf43668db407692deaf2023d4adbeeef9633.tar.xz | |
arm: dts: vexpress-v2p-ca15_a7: Add cpu dynamic-power-coefficient information
A CPUfreq driver, like the ARM big.LITTLE driver used on the TC2 board,
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}.
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/arm/boot/dts')
| -rw-r--r-- | arch/arm/boot/dts/vexpress-v2p-ca15_a7.dts | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/arch/arm/boot/dts/vexpress-v2p-ca15_a7.dts b/arch/arm/boot/dts/vexpress-v2p-ca15_a7.dts index a2ccacd07f4f..00cd9f5bef2e 100644 --- a/arch/arm/boot/dts/vexpress-v2p-ca15_a7.dts +++ b/arch/arm/boot/dts/vexpress-v2p-ca15_a7.dts @@ -42,6 +42,7 @@ cci-control-port = <&cci_control1>; cpu-idle-states = <&CLUSTER_SLEEP_BIG>; capacity-dmips-mhz = <1024>; + dynamic-power-coefficient = <990>; }; cpu1: cpu@1 { @@ -51,6 +52,7 @@ cci-control-port = <&cci_control1>; cpu-idle-states = <&CLUSTER_SLEEP_BIG>; capacity-dmips-mhz = <1024>; + dynamic-power-coefficient = <990>; }; cpu2: cpu@2 { @@ -60,6 +62,7 @@ cci-control-port = <&cci_control2>; cpu-idle-states = <&CLUSTER_SLEEP_LITTLE>; capacity-dmips-mhz = <516>; + dynamic-power-coefficient = <133>; }; cpu3: cpu@3 { @@ -69,6 +72,7 @@ cci-control-port = <&cci_control2>; cpu-idle-states = <&CLUSTER_SLEEP_LITTLE>; capacity-dmips-mhz = <516>; + dynamic-power-coefficient = <133>; }; cpu4: cpu@4 { @@ -78,6 +82,7 @@ cci-control-port = <&cci_control2>; cpu-idle-states = <&CLUSTER_SLEEP_LITTLE>; capacity-dmips-mhz = <516>; + dynamic-power-coefficient = <133>; }; idle-states { |