I am using Orange PI PC for running a Deluge (torrents) and FTP server.
I have noticed that when Deluge is downloading something, the RAM is getting filled up. At some point the kswapd0 kicks in and start using 100% of one CPU core.
This is going on until I manually release the memory, eather with reboot or with "echo 1 > /proc/sys/vm/drop_caches".
Here you can see kswapd0 with "top":
However, the kswapd0 is not visible on htop, but it shows one core at 100%. The memory usage is 111 MB.
But "free -m" command shows that 865 MB of memory is used.