On Mon, Nov 2, 2015 at 3:15 AM, Dietmar Eggemann dietmar.eggemann@arm.com wrote:
On 10/26/2015 04:42 PM, Nitish Ambastha wrote:
Dear All
Hi Nitish,
Hi Dietmar
Thanks for your response
I am going through the EAS project work and trying to port them on my ARM based SMP system (3.10 Linux version) Could you please help me clarify, will EAS be helpful in terms of power/performance for SMP systems as well?
It depends on the topology (single/multi-cluster) and the cpufreq (per cpu/cluster frequency scaling)/cpuidle (per cpu/cluster power gating) capabilities of your platform. Could you share them with the list please?
It is a quad core in-order ARM Cortex A7MP, single cluster SMP, with cluster frequency scaling and per cpu power gating. I don't think this topology will benefit from the energy model of scheduler as much as a heterogeneous system or a multi-cluster system
Leo Yan (Linaro) is evaluating EAS on an dual-cluster SMP machine (hikey) with per-system !!! frequency scaling and per cpu power gating.
He already figured that some of the code paths in energy_aware_wake_cpu() have to be adapted to fully work for dual-cluster SMP systems (see email thread of 22/46 and 32/46 of EAS RFCv5 on LKML).
Do you really have to use 3.10? The back-port effort is IMHO way too high
Actually I am trying to benchmark this on a mobile device board which is already running 3.10. I have just ported the patches from https://git.linaro.org/kernel/eas-backports.git (3.10 based repository) However, I could not get sched-dvfs related patches for 3.10, and the effort here is big. Could you please suggest me a better candidate to check for 3.10?
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-- Dietmar
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Thanks Nitish Ambastha