The Test - Simultaneous Up and Downlink
So I set out to see if either DD-WRT or Tomato would smooth out the GL's high throughput variation and raise the maximum number of simultaneous sessions that it would support. My first step was to load up the current firmware release (4.30.12) and rerun my standard set of router tests.
Figure 1 shows that the high throughput variation that I saw with Linksys version 4.30.2 firmware is still there. (You can see the orignal IxChariot plot here.)
Figure 2: Linksys WRT54GL simultaneous up / down throughput with Linksys 4.30.12 firmware
The results with DD-WRT v23sp2 loaded are shown in Figure 3. It looks like DD-WRT allows uplink and downlink throughput to not battle each other as it does in the factory firmware. But when both up and downlink traffic are simultaneously high, uplink gets most of the bandwidth.
Note that I checked that the DD-WRT QoS features were disabled and also tried the SPI firewall disable. Neither changed the imbalance between up and downlink throughput.
Figure 3: Linksys WRT54GL simultaneous up / down throughput with DD-WRT v23sp2
Figure 4 shows the same simultaneous up and downlink test run with Tomato 1.19 loaded. While the behavior is different than that of the factory firmware, I don't think that you can say that it's better.