linux-kernel - [PATCH 1/3] ARM: exynos_defconfig: Enable SCHED

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Date:   Mon, 27 Jan 2020 21:54:51 +0000
From:   lukasz.luba@....com
To:     kgene@...nel.org, krzk@...nel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, linux-pm@...r.kernel.org
Cc:     myungjoo.ham@...sung.com, kyungmin.park@...sung.com,
        cw00.choi@...sung.com, robh+dt@...nel.org, mark.rutland@....com,
        b.zolnierkie@...sung.com, lukasz.luba@....com,
        dietmar.eggemann@....com
Subject: [PATCH 1/3] ARM: exynos_defconfig: Enable SCHED_MC

From: Lukasz Luba <lukasz.luba@....com>

Since the 'capacities-dmips-mhz' are present in the CPU nodes, make use of
this knowledge in smarter decisions during scheduling.

The values in 'capacities-dmips-mhz' are normilized, this means that i.e.
when CPU0's capacities-dmips-mhz=100 and CPU1's 'capacities-dmips-mhz'=50,
cpu0 is twice fast as CPU1, at the same frequency. The proper hirarchy
in sched_domain topology could exploit the SoC architecture advantages
like big.LITTLE. Enabling the SCHED_MC will create two levels in
sched_domain hierarchy, which might be observed in:

grep . /proc/sys/kernel/sched_domain/cpu*/domain*/{name,flags}
/proc/sys/kernel/sched_domain/cpu0/domain0/name:MC
/proc/sys/kernel/sched_domain/cpu0/domain1/name:DIE
...
/proc/sys/kernel/sched_domain/cpu0/domain0/flags:575
/proc/sys/kernel/sched_domain/cpu0/domain1/flags:4223

Signed-off-by: Lukasz Luba <lukasz.luba@....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 e7e4bb5ad8d5..1db857056992 100644
--- a/arch/arm/configs/exynos_defconfig
+++ b/arch/arm/configs/exynos_defconfig
@@ -8,6 +8,7 @@ CONFIG_PERF_EVENTS=y
 CONFIG_ARCH_EXYNOS=y
 CONFIG_CPU_ICACHE_MISMATCH_WORKAROUND=y
 CONFIG_SMP=y
+CONFIG_SCHED_MC=y
 CONFIG_BIG_LITTLE=y
 CONFIG_NR_CPUS=8
 CONFIG_HIGHMEM=y
-- 
2.17.1