High RAM usage on TP-Link Archer C7 v4

[rbino]

I flashed this firmware since my TP-Link Archer C7 v4 couldn't keep up with the 1Gbps internet using stock OpenWRT (it capped at ~300Mbps).

The firmware worked fine and I was able to hit wire speed, but after some time the network started behaving in a strange way. After some debugging I determined that the cause of the problem was that RAM was quickly exhausted, leading dnsmasq to crash with messages like these:

daemon.crit dnsmasq[4489]: could not get memory
daemon.crit dnsmasq[4489]: FAILED to start up

I tried flashing the stock firmware and compare the memory usage. This is the stock firmware with its factory configuration:

This is the openwrt-sfe-flowofflead-ath79 firmware with its factory configuration about a minute after flashing:

In the second case the system starts with ~55% free memory and quickly drops to around 40%.

Is this normal behaviour? And if so, what can I do to free up some memory so that I can use the firmware without DHCP failing after some time? Is there a way to debug which applications are using up the memory?

[JurandyRafael]

Hello I have version 5 of this router and I still haven't detected this problem for my version but I'll give you a tip and I hope it helps. You can sometimes run this command to free memory in an ssh terminal:

sync ; echo 3 > /proc/sys/vm/drop_caches

For better convenience you can create a script that contains this command for the router to run on its own. Automating this process.

It's not the best solution but it's a way to get around the problem, at least for the time being.