Pine64 Cluster economy

[tkaiser]

It was ~65 C all the time, and never below 1.15GHz.

Please don't get offended since I'm not talking to you, just writing some stuff as a reference for others that might come across this thread interested in cluster/performance experiences.

65°C with heatsink is simply not possible with these types of workloads (maybe single-threaded but not when running on 4 fully utilized cores). I just gave it a try on my Pine64 without heatsink. I'm currently refraining from putting a heatsink on it to be able to help the guys doing A64 mainline kernel work -- for both reason as well as some thermal/throttling results of really demanding workloads using NEON optimizations see starting from here http://irclog.whitequark.org/linux-sunxi...#16481377;



Calculated average cpufreq (see below) has been 950 MHz that means by comparing my 2245 sec seconds duration compared with your 1949 means you ran at an average 1095 MHz given you used the same THS settings (keeping SoC temp at around 90°C). This means also that povray with these optimizations can't be considered a heavy workload (please compare with cpuburn-a53 in the link above -- with this kind of code you end up at 600 MHz throttling frequency without a heatsink). BTW: Maybe I did something wrong:

apt-get install povray time --> http://pastebin.com/Ynebb1sF

Further readings regarding performance optimizations:

https://github.com/longsleep/build-pine64-image/pull/3
http://forum.pine64.org/showthread.php?t...10#pid3410

And in addition to the improvements we made back in March see also this (adding even more cpufreq steps helps with performance on both H3 and A64 as soon as throttling occurs  )

https://github.com/igorpecovnik/lib/issu...-220017171

BTW: An easy way to calculate average cpufreq when running a benchmark or a real workload while throttling occured is to switch to performance governor as root

Code:

echo performance >/sys/devices/system/cpu/cpu0/cpufreq/scaling_governor

and then do

Code:

cat /sys/devices/system/cpu/cpu0/cpufreq/stats/time_in_state >/tmp/before
$benchmark
cat /sys/devices/system/cpu/cpu0/cpufreq/stats/time_in_state >/tmp/after

Then do the math.