Madozu

I am running a headless cubietruck with Armbian standard kernel (5.10.4-sunxi as of now). System is Ubuntu Focal Fossa with "linux-focal-root-current-cubietruck 20.11.6" installed. Cubietruck has uboot and /boot  on SD-Card and the system is on a SATA-attached SSD. CPU load average over 20s (vmstat 20) is like this:
 
procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu----- r b swpd free buff cache si so bi bo in cs us sy id wa st 0 0 0 1827484 18008 137776 0 0 0 0 121 78 0 5 94 0 0 1 0 0 1827484 18008 137772 0 0 0 0 109 70 0 5 95 0 0 0 0 0 1827232 18008 137776 0 0 0 0 96 57 0 5 95 0 0 1 0 0 1827232 18008 137776 0 0 0 0 102 56 0 5 95 0 0 1 0 0 1827232 18008 137776 0 0 0 0 109 72 0 5 95 0 0 1 0 0 1827232 18008 137776 0 0 0 0 92 49 0 5 95 0 0 2 0 0 1827232 18008 137776 0 0 0 0 95 49 0 5 95 0 0 1 0 0 1827232 18008 137776 0 0 0 0 112 75 0 5 95 0 0 0 0 0 1827232 18008 137776 0 0 0 0 92 52 0 5 95 0 0  
This is better than what I saw with older (e.g. 4.x) kernels but still around 5% CPU usage coming from "kworker/1:3-events_freezable_power_". When removing the modules for ADC (sun4i_gpad and sun4i_gpad_iio) the CPU usage drops down to <1% in average:
procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu----- r b swpd free buff cache si so bi bo in cs us sy id wa st 1 0 0 1826784 18020 137772 0 0 0 9 41 46 0 0 100 0 0 1 0 0 1826540 18020 137772 0 0 0 0 52 60 0 0 99 0 0 1 0 0 1826540 18020 137772 0 0 0 0 39 44 0 0 100 0 0 1 0 0 1826540 18020 137772 0 0 0 0 39 44 0 0 100 0 0 1 0 0 1826532 18020 137776 0 0 0 1 61 69 0 0 99 0 0 1 0 0 1826532 18020 137776 0 0 0 0 45 48 0 0 100 0 0 1 0 0 1826532 18020 137776 0 0 0 0 34 40 0 0 100 0 0 1 0 0 1826532 18020 137776 0 0 0 0 62 69 0 0 99 0 0 1 0 0 1826532 18020 137776 0 0 0 0 35 41 0 0 100 0 0 1 0 0 1826532 18020 137776 0 0 0 0 34 40 0 0 100 0 0  
However as stated previously, removing those kernel modules breaks the CPU temp sensor display in the OS. What I recommend to do is running this command to remove the modules contributing to the CPU consumption:
sudo rmmod sun4i_gpadc sun4i_gpadc_iio  
If you're happy with the result, put the above statement into /etc/rc.local to run at every boot. Blacklisting the above modules in /etc/modprobe.d only partially works as module sun4i_gpadc is loaded anyway.

I am running a headless cubietruck with Armbian standard kernel (5.10.4-sunxi as of now). System is Ubuntu Focal Fossa with "linux-focal-root-current-cubietruck 20.11.6" installed. Cubietruck has uboot and /boot  on SD-Card and the system is on a SATA-attached SSD. CPU load average over 20s (vmstat 20) is like this:
 
procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu----- r b swpd free buff cache si so bi bo in cs us sy id wa st 0 0 0 1827484 18008 137776 0 0 0 0 121 78 0 5 94 0 0 1 0 0 1827484 18008 137772 0 0 0 0 109 70 0 5 95 0 0 0 0 0 1827232 18008 137776 0 0 0 0 96 57 0 5 95 0 0 1 0 0 1827232 18008 137776 0 0 0 0 102 56 0 5 95 0 0 1 0 0 1827232 18008 137776 0 0 0 0 109 72 0 5 95 0 0 1 0 0 1827232 18008 137776 0 0 0 0 92 49 0 5 95 0 0 2 0 0 1827232 18008 137776 0 0 0 0 95 49 0 5 95 0 0 1 0 0 1827232 18008 137776 0 0 0 0 112 75 0 5 95 0 0 0 0 0 1827232 18008 137776 0 0 0 0 92 52 0 5 95 0 0  
This is better than what I saw with older (e.g. 4.x) kernels but still around 5% CPU usage coming from "kworker/1:3-events_freezable_power_". When removing the modules for ADC (sun4i_gpad and sun4i_gpad_iio) the CPU usage drops down to <1% in average:
procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu----- r b swpd free buff cache si so bi bo in cs us sy id wa st 1 0 0 1826784 18020 137772 0 0 0 9 41 46 0 0 100 0 0 1 0 0 1826540 18020 137772 0 0 0 0 52 60 0 0 99 0 0 1 0 0 1826540 18020 137772 0 0 0 0 39 44 0 0 100 0 0 1 0 0 1826540 18020 137772 0 0 0 0 39 44 0 0 100 0 0 1 0 0 1826532 18020 137776 0 0 0 1 61 69 0 0 99 0 0 1 0 0 1826532 18020 137776 0 0 0 0 45 48 0 0 100 0 0 1 0 0 1826532 18020 137776 0 0 0 0 34 40 0 0 100 0 0 1 0 0 1826532 18020 137776 0 0 0 0 62 69 0 0 99 0 0 1 0 0 1826532 18020 137776 0 0 0 0 35 41 0 0 100 0 0 1 0 0 1826532 18020 137776 0 0 0 0 34 40 0 0 100 0 0  
However as stated previously, removing those kernel modules breaks the CPU temp sensor display in the OS. What I recommend to do is running this command to remove the modules contributing to the CPU consumption:
sudo rmmod sun4i_gpadc sun4i_gpadc_iio  
If you're happy with the result, put the above statement into /etc/rc.local to run at every boot. Blacklisting the above modules in /etc/modprobe.d only partially works as module sun4i_gpadc is loaded anyway.

I tested the recently added sunxi-dev patch to improve the SATA write speed. Here are the results:
 
Board: Cubietruck
OS: Ubuntu Bionic (18.04.2), Armbian 5.86
Kernel: 5.1.0 with and without RFC-drivers-ata-ahci_sunxi-Increased-SATA-AHCI-DMA-TX-RX-FIFOs.patch
SATA-device: SAMSUNG SSD 830 Series, 256GB
 
Measurement method: dd if=/dev/zero of=/tesfile bs=? count=? oflag=direct
bs: measured 4k, 64k and 1M block sizes
count: adjusted to ensure that data written is ~500MB
 
Measurements below are made with kernel 5.1.0 without (before) and with the mentioned patch:
dd bs Before MB/s After MB/s Increase 4k 13.3 19.0 43% 64k 35.9 82.0 128% 1M 42.5 112.0 164% As you can see, the SATA write speed improved, especially when using larger block sizes. Up to now, no negative side-effects encountered.