BTW: Anyone interested in this topic (ARMv8 code with all optimisations turned on, sane dvfs settings, relationship between heat dissipation and performance, relationship between clockspeed, heat and stability and so on... everything except of benchmarks!
) might have a look here:
http://linux-sunxi.org/User:Tkaiser#Reli..._on_Pine64
Back to benchmarks: In the following graph we used
cpuminer (rather efficient and using NEON optimised code) to get an idea how throttling affects performance: With a fan close to the SoC's
heatsink and clockspeed adjusted to 1200MHz we get stable 3.440 khash/s. After switching the fan off the SoC's temperature increases and performance decreases since maximum clockspeeds will be lower to prevent overheating (these are pretty conservative settings, you could also increase the thermal tresholds but it makes not that much sense):
What this graph does
not show is how important software/settings for benchmark scores are since three weeks ago this benchmark would've shown stable ~830 khash/s instead. Why? Since back then longsleep's OS images relied on Allwinner's default throttling settings (killing CPU cores and never bringing them back). One week ago the results without a fan would've also been drastically lower since we just recently improved throttling behaviour again by using more intermediate steps which automatically improves peak performance under constant full load. And this is still WiP, see the link below.
What's also interesting when using 'benchmarks that matter' [TM] (with all compiler/code optimisations turned on and not random stuff that runs partially only single threaded as common on openbenchmarking.org) is how better A64 performs when compared to eg. H3 (used on Orange Pis for example):
https://github.com/longsleep/build-pine6...-196267397 (same clockspeed, no throttling -- without monitoring this stuff in parallel you just fool yourself when testing since you get random results that are more influenced by things like ambient temperature than anything else)