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authorVincent Guittot <vincent.guittot@linaro.org>2018-07-11 10:34:46 +0200
committerWei Xu <xuwei5@hisilicon.com>2018-07-17 12:19:25 +0100
commita5956defe5a537447a83de9b4bcd6a7c9aa1cc74 (patch)
tree62a24d08511b044107c9645ff45c3396cc509ff8 /arch/arm64/boot/dts/hisilicon/hi6220.dtsi
parent8883ac1db3e284e9ad48ddad37f5eb3c2730510d (diff)
arm64: hikey960: update idle-states
Update entry/exit latency and residency time of hikey960 to use more realistic figures based on unitary tests done on the platform. The complete results (in us) : big cluster cluster CPU max entry latency 800 400 max exit latency 2900 550 residency 903Mhz 5000 1500 residency 2363Mhz 0 1500 little cluster cluster CPU max entry latency 500 400 max exit latency 1600 650 residency 533Mhz 8000 4500 residency 1844Mhz 0 1500 We can see that the residency time depends of the running OPP which is not handled for now. Then we also have to take into account the constraint of a residency time shorter than the tick to get full advantage of idle loop reordering(tick is stopped if idle duration is higher than tick period). Finally the selected residency value are : big cluster cluster CPU residency 3700 1500 little cluster cluster CPU residency 3500 1500 A simple test with a task waking up every 11.111ms shows improvement: - 5% a lowest OPP - 22% at highest OPP The period has been chosen: - to be shorter than old cluster residency time and longer than new residency time of cluster off C-state - to prevent any sync with tick (4ms) when running tests that can add some variances between tests Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org> Reviewed-by: Leo Yan <leo.yan@linaro.org> Signed-off-by: Wei Xu <xuwei5@hisilicon.com>
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