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SubjectRe: [PATCH 3/3] ARM: exynos_defconfig: Enable Energy Model framework
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Hi,

On 1/27/20 10:54 PM, lukasz.luba@arm.com wrote:
> From: Lukasz Luba <lukasz.luba@arm.com>
>
> Enable the Energy Model (EM) brings possibility to use Energy Aware
> Scheduler (EAS). This compiles the EM but does not enable to run EAS in
> default. The EAS only works with SchedUtil - a CPUFreq governor which
> handles direct requests from the scheduler for the frequency change. Thus,
> to make EAS working in default, the SchedUtil governor should be
> configured as default CPUFreq governor. Although, the EAS might be enabled
> in runtime, when the EM is present for CPUs, the SchedUtil is compiled and
> then set as CPUFreq governor, i.e.:
>
> echo schedutil > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
> echo schedutil > /sys/devices/system/cpu/cpu4/cpufreq/scaling_governor
>
> To check if EAS is ready to work, the read output from the command below
> should show '1':
> cat /proc/sys/kernel/sched_energy_aware
>
> To disable EAS in runtime simply 'echo 0' to the file above.
>
> Some test results, which stress the scheduler on Odroid-XU3:
> hackbench -l 500 -s 4096
> With mainline code and with this patch set.
>
> The tests have been made with and without CONFIG_PROVE_LOCKING (PL)
> (which is set to =y in default exynos_defconfig)
>
> | this patch set | mainline
> |-----------------------------------------------|---------------
> | performance | SchedUtil | SchedUtil | performance
> | governor | governor | governor | governor
> | | w/o EAS | w/ EAS |
> ----------------|---------------|---------------|---------------|---------------
> hackbench w/ PL | 12.7s | 11.7s | 12.0s | 13.0s - 12.2s
> hackbench w/o PL| 9.2s | 8.1s | 8.2s | 9.2s - 8.4s

Would you happen to have measurements of how much power is
saved by running hackbench using "SchedUtil governor w/ EAS"
instead of "SchedUtil governor w/o EAS"?

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics

> Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
> ---
> arch/arm/configs/exynos_defconfig | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/arch/arm/configs/exynos_defconfig b/arch/arm/configs/exynos_defconfig
> index 1db857056992..c0f8ecabc607 100644
> --- a/arch/arm/configs/exynos_defconfig
> +++ b/arch/arm/configs/exynos_defconfig
> @@ -18,6 +18,7 @@ CONFIG_ZBOOT_ROM_BSS=0x0
> CONFIG_ARM_APPENDED_DTB=y
> CONFIG_ARM_ATAG_DTB_COMPAT=y
> CONFIG_CMDLINE="root=/dev/ram0 rw ramdisk=8192 initrd=0x41000000,8M console=ttySAC1,115200 init=/linuxrc mem=256M"
> +CONFIG_ENERGY_MODEL=y
> CONFIG_CPU_FREQ=y
> CONFIG_CPU_FREQ_STAT=y
> CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND=y

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