Tomato/EasyTomato Router High CPU When Downloading 100Mbps+ Fix

I have an ASUS NT-16 Router which has EasyTomato 0.8 (the newest version) installed. EasyTomato is pretty much an easier-to-use, enhanced version of the popular Tomato/TomatoUSB router firmware. It works well for the most part, but I have noticed that if there are high-speed broadband downloads that are near or exceeding 100 Mbps for several minutes, I could no longer browse the web. It has been an annoyance for months so I decided to really investigate and then hopefully find a solution.

I noticed that firstly the error message I get when browsing the web all stem from "server not found" resulting from the names of the sites not being resolved. Basically, there was a problem with DNS, which the router was configured to "pass through". I had configured the router to route route DNS queries asked for it to the proper servers, such as the Google public DNS ones like 8.8.8.8. When I tried to log into the router configuration to see what what was going one, the hourglass would just keep on spinning with no response, despite the downloads still happily churning along at high-speeds. Once in a while, I am able to get in, and I notice that the CPU load is over 90%.

With no heavy-duty downloads occurring, I decided to turn on the SSH server on my Tomato router so I can get into the system via Putty (an excellent free SSH program for Windows). The IP of my router is 192.168.1.1, and I was able to ssh into it using the username of "root" with a password that matches the web interface.

Once inside, I typed top and pressed ENTER. Top is a Linux/UNIX command that shows you which processes are taking up the most CPU, kind of a text-based version of Window's Task Manager. You can enter capital letter P to sort by % of CPU usage. I then started up the download tasks that would normally "flood" the router, and this was the out of "top" during the heavy download session:

  


Mem: 25584K used, 101400K free, 0K shrd, 3200K buff, 9364K cached



CPU:   1% usr   2% sys   0% nic   3% idle   0% io   1% irq  90% sirq



Load average: 1.31 0.59 0.61 4/31 5539



PID  PPID USER     STAT   VSZ %VSZ %CPU COMMAND



5446     1 nobody   S     1072   1%  25% dnsmasq -c 1500 --log-async



2249  2245 root     R     1564   1%  17% top -d1



5425  2704 root     R     1564   1%   7% top



322     1 root     S     1232   1%   2% buttons



922     1 root     S     2632   2%   1% httpd



3     2 root     SW


2703  2681 root     S     1120   1%   0% dropbear -p 22 -a



4     2 root     SW


2241   922 root     S     2656   2%   0% httpd



481     1 root     S     1580   1%   0% crond



2704  2703 root     S     1576   1%   0% -sh



928     1 root     S     1572   1%   0% udhcpc -i vlan2 -b -s dhcpc-event -H unknown -m -S



324   323 root     S     1564   1%   0% /bin/sh



2245  2244 root     S     1560   1%   0% {.wxdjAka4} /bin/sh /tmp/.wxdjAka4



2244  2241 root     S     1560   1%   0% sh -c /tmp/.wxdjAka4 2>&1



326     1 root     S     1556   1%   0% syslogd -L -s 500 -b 2



328     1 root     S     1556   1%   0% klogd



1     0 root     S     1248   1%   0% /sbin/init noinitrd



323     1 root     S     1200   1%   0% console



2681     1 root     S     1056   1%   0% dropbear -p 22 -a



490     1 root     S      980   1%   0% cstats



483     1 root     S      888   1%   0% rstats



281     1 root     S      608   0%   0% hotplug2 --persistent --no-coldplug



89     2 root     SW


45     2 root     SW       0   0%   0% [pdflush]



44     2 root     SW       0   0%   0% [pdflush]



5     2 root     SW


18     2 root     SW


2     0 root     SW


46     2 root     SW


47     2 root     SW