Posted: Sun Feb 13, 2011 15:15 Post subject: Linksys E2000 Slow LAN throughput with DD-WRT
Hi there,
I recently purchased a Linksys E-2000 gigabit N router. Anyway, I ran a speedtest on it before installing DD-WRT and was getting 95~98 Megabit speed from the internet to the LAN (I have 100 mb cable connection), however, once I installed WRT and ran the test again this dropped down to 30.
I reinstalled the Linksys firmware and it shot back up to 95 ~ 98. Same test site, same server.
I am running 14929 firmware for the E-2000.
Any suggestions? Would like to use DD-WRT but the slow WAN/LAN throughput is kind of offputting.
You should be getting much more than 30mbps if you're wired not wireless with default settings, but dd-wrt routing throughput is slower than stock firmware due to features. An e2000 should be somewhere around 60-70mbps with default settings and the only way it will achieve ~100mbps with dd-wrt is if your overclock it. _________________ Read the forum announcements thoroughly! Be cautious if you're inexperienced.
Available for paid consulting. (Don't PM about complicated setups otherwise)
Looking for bricks and spare routers to expand my collection. (not interested in G spec models)
Posted: Mon Feb 21, 2011 19:33 Post subject: E2000 poor performance post-DD-WRT compared to stock
I'm having this issue as well. I was getting high 70 - 90 download speeds before DD-WRT, after installing DD-WRT (using builds 14929-big and 15962-big) I'm only getting mid-to-high 30's. I have gone back-and-forth a couple times to confirm that the observations are repeatable.
Any ideas or suggestions on tweaking any of the settings to improve this? I'm going back to stock if this is the best I can do.
I had similar problem with the wired connection. My internet is 120/10mbps and with build 14929 E2000 was able to download about 40mbps. I put back original firmware and speed is back to normal at 120mbps on LAN and about 55 on wireless.
I have a connection that is over 50Mb/s down and can hit at least 55Mb/s with DD-WRT installed doing just NAT.
I logged into the console and ran 'top' and I noticed the SIRQ % spikes >90% when attempting to download at the high speeds. With QoS enabled, the top speed at hits about 32Mb/s download.
I'm guessing that SIRQs are System Interrupt Requests (driver/hardware communications). The throughput performance is limited because of the poor efficiency of the network drivers/kernel.
Now the stock firmware is able to reach much higher speeds so why is DD-WRT's implementation of just NAT so inefficient?
Thanks - ill give it a try... If this works (as I've seen it posted elsewhere) why is it not set by default? Is there a downside to changing the max backlog setting?
Thanks - ill give it a try... If this works (as I've seen it posted elsewhere) why is it not set by default? Is there a downside to changing the max backlog setting?
I don't know. I have a reasonably fast Kong build and it is set to 30. But Kong builds could brick your router. _________________ 2 times APU2 Opnsense 21.1 with Sensei
2 times RT-AC56U running DD-WRT 45493 (one as Gateway, the other as AP, both bridged with LAN cable)
3 times Asus RT-N16 shelved
E4200 V1 running freshtomato 2020.8 (bridged with LAN cable)
3 times Linksys WRT610N V2 converted to E3000 and 1 original E3000 running freshtomato 2020.8 (bridged with LAN cable)
I searched Google and found that neetdev_max_backlog is a Linux TCP tuning setting that basically increases the queue size of incoming packets (syn requests) waiting to be processed by the next TCP Receive process.
While increasing this does allow for more packets to be queued before being dropped, there is still a limit to how fast the hardware ca process the packets. Here are my results.
I also tried to set netdev_max_backlog to 2000 or 4096 with no change in performance. Checking top during these tests, I found the CPU load to be maxed out from the SIRQs or Software Interrupt Requests.
I did these tests just to figure out how much routing performance this router could handle with DD-WRT. With QoS/HFSC enabled, the CPU becomes pegged at the max I could get out of it was about 38Mbits/sec.