Re: [PATCH] arm64: dts: hisilicon: Add hi3660 cpu capacity-dmips-mhz information
From: Valentin Schneider
Date: Wed Dec 13 2017 - 10:16:22 EST
Hi Leo,
On 12/13/2017 02:53 PM, Leo Yan wrote:
Hi Valentin,
On Wed, Dec 13, 2017 at 02:21:06PM +0000, Valentin Schneider wrote:
The following dt entries are added:
cpus [0-3] (Cortex A53):
- capacity-dmips-mhz = <592>;
cpus [4-7] (Cortex A73):
- capacity-dmips-mhz = <1024>;
Those values were obtained by running dhrystone 2.1 on a
HiKey960 with the following procedure:
- Offline all CPUs but CPU0 (A53)
- Set CPU0 frequency to maximum
- Run Dhrystone 2.1 for 20 seconds
- Offline all CPUs but CPU4 (A73)
- set CPU4 frequency to maximum
- Run Dhrystone 2.1 for 20 seconds
The results are as follows:
A53: 129633887 loops
A73: 287034147 loops
Seems to me the capacity-dmips-mhz should be:
CA53: 129633887 / 20 / 1844 = 3515
CA73: 287034147 / 20 / 2362 = 6076
After normalized to range [0..1024], we could get:
CA53: 592
CA73: 1024
Yes, that's the "direct approach". I wanted to underline the fact that
there are two different max frequencies so what I followed would be:
1) Computing the performance ratio:
(129633887 / 287034147) * 1024 = 462.47
2) Scaling that to the same frequency scale:
462.47 * (2362/1844) = 592.38
Which gives the same end result (it's the same equation but split in two
steps). Also it makes it easy to check that the cpu_capacity sysfs entry
for the A53s gets correctly set (to 462).
Reviewed-by: Leo Yan <leo.yan@xxxxxxxxxx>
By scaling those values so that the A73s use 1024, we end up with 462
for the A53s. However, they have different maximum frequencies:
1.844GHz for A53s and 2.362GHz for A73s. Thus, we can scale the A53
value to truly represent dmips per MHz, and we end up with 592.
The impact of this change can be verified on HiKey960:
$ cat /sys/devices/system/cpu/cpu*/cpufreq/scaling_cur_freq
1844000
1844000
1844000
1844000
2362000
2362000
2362000
2362000
$ cat /sys/devices/system/cpu/cpu*/cpu_capacity
462
462
462
462
1024
1024
1024
1024
Signed-off-by: Valentin Schneider <valentin.schneider@xxxxxxx>
---
arch/arm64/boot/dts/hisilicon/hi3660.dtsi | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/arch/arm64/boot/dts/hisilicon/hi3660.dtsi b/arch/arm64/boot/dts/hisilicon/hi3660.dtsi
index ab0b95b..04a8d28 100644
--- a/arch/arm64/boot/dts/hisilicon/hi3660.dtsi
+++ b/arch/arm64/boot/dts/hisilicon/hi3660.dtsi
@@ -61,6 +61,7 @@
enable-method = "psci";
next-level-cache = <&A53_L2>;
cpu-idle-states = <&CPU_SLEEP &CLUSTER_SLEEP_0>;
+ capacity-dmips-mhz = <592>;
};
cpu1: cpu@1 {
@@ -70,6 +71,7 @@
enable-method = "psci";
next-level-cache = <&A53_L2>;
cpu-idle-states = <&CPU_SLEEP &CLUSTER_SLEEP_0>;
+ capacity-dmips-mhz = <592>;
};
cpu2: cpu@2 {
@@ -79,6 +81,7 @@
enable-method = "psci";
next-level-cache = <&A53_L2>;
cpu-idle-states = <&CPU_SLEEP &CLUSTER_SLEEP_0>;
+ capacity-dmips-mhz = <592>;
};
cpu3: cpu@3 {
@@ -88,6 +91,7 @@
enable-method = "psci";
next-level-cache = <&A53_L2>;
cpu-idle-states = <&CPU_SLEEP &CLUSTER_SLEEP_0>;
+ capacity-dmips-mhz = <592>;
};
cpu4: cpu@100 {
@@ -101,6 +105,7 @@
&CPU_SLEEP
&CLUSTER_SLEEP_1
>;
+ capacity-dmips-mhz = <1024>;
};
cpu5: cpu@101 {
@@ -114,6 +119,7 @@
&CPU_SLEEP
&CLUSTER_SLEEP_1
>;
+ capacity-dmips-mhz = <1024>;
};
cpu6: cpu@102 {
@@ -127,6 +133,7 @@
&CPU_SLEEP
&CLUSTER_SLEEP_1
>;
+ capacity-dmips-mhz = <1024>;
};
cpu7: cpu@103 {
@@ -140,6 +147,7 @@
&CPU_SLEEP
&CLUSTER_SLEEP_1
>;
+ capacity-dmips-mhz = <1024>;
};
idle-states {
--
2.7.4