The discussion is very interesting. German is perfectly fine, but my German grammar is not perfect. Zram works by having a compressed block device in memory, so it does not write to flash.
My local setup has an 841 and a CPE210. The 841 is connected to my home 13/1 DSL and the 210 through mesh-on-lan (and mesh-wlan). Average number of clients is 1. The maximum number of clients I’ve seen is 8. The VPN tunnel is unencrypted, so in theory the 841’s cpu is powerful enough for this DSL line. However, the 841 is seeing a very high load is relatively unstable. But it is not clear what is causing the high load. The cpu is still idling a bit and there is still ~6 mb of free memory.
As the discussion in the thread points out, using ZRAM is not likely to help, but I wanted to find out anyway. I have a little too much free time on my hands right now. (If anybody in the ffrn region needs data scientist that compiles linux distro’s for fun, contact me. ) So I tried it out. I compiled the the 2017.1.4 version of gluon and then manually scp’d the modules required for zram and the swapon binary. The zram packages are all part of the standard Lede build, but opkg is not installed in the image that is on my 841.
I first tried a 10 mb zram swap device and the device started thrashing straight away. A 5mb swap device did work, but the machine rebooted again after a couple of hours. I then tried a 3 mb and that was stable. However, the device was struggling more. The load is ~16 and the CPU is constantly being hammered. For reference, the output of `free’ is copied here:
total used free shared buffers cached
Mem: 27792 24064 3728 0 1176 1712
-/+ buffers/cache: 21176 6616
Swap: 2928 2908 20
For reference, the memory load without zram looks like this:
total used free shared buffers cached
Mem: 27792 21776 6016 132 1276 1760
-/+ buffers/cache: 18740 9052
Swap: 0 0 0
So doing zram has not been an improvement. The CPU’s is completely hammered. Again, this was expected given the discussion in the thread.
It still puzzles me what is causing the high load on this machine (without zram enabled). The machine has spare CPU cycles and memory. And it also does not seem to be spawning processes constantly. What is causing the high load? Is this already known? Or can I investigate this further?
Thanks for all the input!
P.S. A completely different topic is why a leave node, like mine, needs to have a 3 copies of the routing table of 1500+ entries. The routing table only needs ~11 entries (3 neighbours and 8 clients). All traffic with an unknown destination can just be forwarded to the VPN gateway.