Installed the latest Openwrt firmware, a few days back.
My Pi 3B is set up as following:
External USB wifi (148f:3070 Ralink RT2870/RT3070 Wireless Adapter) to receive wifi and another wifi router, connected to Raspberry's Lan is used as an AP, to re-transmit the wifi.
The problem is, I'm getting enormous high load on the Raspberry, without an apparent reason.
High Speed SD card is used.
With the older firmware I used to run (can mention the version), I don't remember such an issue.
Dmesg is displaying a lot of errors, which I found is possible related to the multiple USB devices used, but in my case, only one USB device is connected.
[ 4738.579491] cpufreq: __target_index: Failed to change cpu frequency: -22
[ 4738.589467] bcm2835-cpufreq:bcm2835_cpufreq_set_clock:76: Failed to set clock: 1200000 (-12)
[ 4738.602727] bcm2835-cpufreq:bcm2835_cpufreq_driver_target_index:175: Error occurred setting a new frequency (1200000)
[ 4738.602791] ttyS ttyS0: 82 input overrun(s)
[ 4738.618210] cpufreq: __target_index: Failed to change cpu frequency: -22
[ 4738.618307] bcm2835-cpufreq:bcm2835_cpufreq_set_clock:76: Failed to set clock: 1200000 (-12)
[ 4738.647066] bcm2835-cpufreq:bcm2835_cpufreq_driver_target_index:175: Error occurred setting a new frequency (1200000)
[ 4738.662459] cpufreq: __target_index: Failed to change cpu frequency: -22
[ 4738.672320] bcm2835-cpufreq:bcm2835_cpufreq_set_clock:76: Failed to set clock: 1200000 (-12)
[ 4738.685458] bcm2835-cpufreq:bcm2835_cpufreq_driver_target_index:175: Error occurred setting a new frequency (1200000)
[ 4738.700832] cpufreq: __target_index: Failed to change cpu frequency: -22
[ 4738.710381] bcm2835-cpufreq:bcm2835_cpufreq_set_clock:76: Failed to set clock: 1200000 (-12)
[ 4738.723532] bcm2835-cpufreq:bcm2835_cpufreq_driver_target_index:175: Error occurred setting a new frequency (1200000)
CPU: 0% usr 21% sys 0% nic 78% idle 0% io 0% irq 0% sirq
Load average: 2.63 2.50 2.50 3/80 1982
1981 2 root IW 0 0% 6% [kworker/3:0]
1886 2 root IW 0 0% 5% [kworker/0:0]
28 2 root RW 0 0% 5% [kworker/2:1]
48 2 root IW 0 0% 4% [kworker/1:1]
1887 2 root IW 0 0% 0% [kworker/u8:4]
369 1 root S 1184 0% 0% /sbin/logd -S 64
1901 2 root RW 0 0% 0% [kworker/u8:2]
1905 2 root IW 0 0% 0% [kworker/u8:3]
7 2 root SW 0 0% 0% [ksoftirqd/0]
920 1 root S 4812 1% 0% /usr/bin/ttyd -i br-lan /usr/libexec/login.sh
1982 1148 root R 1204 0% 0% top
24 2 root SW 0 0% 0% [ksoftirqd/3]
19 2 root SW 0 0% 0% [ksoftirqd/2]
8 2 root IW 0 0% 0% [rcu_sched]
394 1 root S 2152 0% 0% /sbin/rpcd -s /var/run/ubus.sock -t 30
1719 1 root S 1840 0% 0% /usr/sbin/wpa_supplicant -B -s -P /var/run/wpa_supplicant-wlan1.pid -D nl80211 -i wlan1 -c /var/run/wpa_supplicant-wlan1.conf -C /var/run/wpa_supplicant
546 1 root S 1712 0% 0% /sbin/netifd
1 0 root S 1524 0% 0% /sbin/procd
584 1 root S 1384 0% 0% /usr/sbin/odhcpd
457 1 dnsmasq S 1308 0% 0% /usr/sbin/dnsmasq -C /var/etc/dnsmasq.conf.cfg01411c -k -x /var/run/dnsmasq/dnsmasq.cfg01411c.pid
644 1 root S 1264 0% 0% /usr/sbin/uhttpd -f -h /www -r zte -x /cgi-bin -t 60 -T 30 -k 20 -A 1 -n 3 -N 100 -R -p 0.0.0.0:80 -p [::]:80
1148 1147 root S 1200 0% 0% -ash
888 1 root S< 1196 0% 0% /usr/sbin/ntpd -n -N -S /usr/sbin/ntpd-hotplug -p 0.openwrt.pool.ntp.org -p 1.openwrt.pool.ntp.org -p 2.openwrt.pool.ntp.org -p 3.openwrt.pool.ntp.org
611 1 root S 1196 0% 0% /usr/sbin/crond -f -c /etc/crontabs -l 5
1739 546 root S 1192 0% 0% udhcpc -p /var/run/udhcpc-wlan1.pid -s /lib/netifd/dhcp.script -f -t 0 -i wlan1 -x hostname:zte -C -O 121
117 1 root S 1168 0% 0% /sbin/ubusd
1147 490 root S 1072 0% 0% /usr/sbin/dropbear -F -P /var/run/dropbear.1.pid -p 22 -K 300 -T 3
490 1 root S 960 0% 0% /usr/sbin/dropbear -F -P /var/run/dropbear.1.pid -p 22 -K 300 -T 3
Also, getting quite a few "Underpower" errors, but I run the Pi of a large Power supply, with an additional power filter. I monitored the voltage (always stable) and played with increasing it up to 5.2V and also tried powering the USB wifi off an independent power supply, cutting the +5v line in between the Raspberry and the Wifi module, but still get the error once in a while.
PS. Sadly, as a new member, can't attache the screenshots...