I stumbled upon this thead googling:  http://www.tolaris.com/2013/07/18/poor- … pberry-pi/

Regarding the output of 'openssl speed' vs openvpn performance,  I'm curious about the final comment "Damn. That’s not a great deal better than I’m seeing with OpenWRT on my Buffalo WZR-HP-G300NH, which can push 13 Mbit over stock OpenVPN"

Looking at the performance results here:  http://wiki.openwrt.org/inbox/benchmark.openssl

The results for his WZR-HP-G300NH are:

Backfire 10.03.1    Atheros AR9132 rev 2    Buffalo WZR-HP-G300NH   
MIPS 24Kc V7.4    266.24 0.9.8t  22143570 6842030 4978220 2494240 3157330 1122950 4812800 4190100    3769420    3.9    143.6 14.5 12.0

The "6953.07k" [1024] quoted on the "Poor OpenVPN performance on Raspberry Pi" link is 6953070 in the above format,   so close to the 6842030 [sha1 value]

I just bought a TP-Link TL-WR1043nd v2,  the results of which are:

trunk r39753    QCA9558@720MHz    TP-Link TL-WR1043nd v2   
MIPS 74Kc V5.0         358.80 1.0.1e    45876220 27233280 12434770 5766490 6425940 2307600    12816040 11099140 9820130    8.3    422.5 44.4 36.4

Tests on my TL-WR1043nd hardware in line with these reported values but I'm seeing only between 300-500Kbyte/sec of openvpn throughput.    Obviously it all depends on what cipher he's using for his vpn and he doesn't say,  just that he's seeing 13Mbit throughput.

Any comments?

On this kind of devices the bottle neck is most likly the CPU or your router. It simply can't handly more traffic over it.

There is clearly a bottleneck but it appears to not be the CPU.   Maybe memory bandwidth but the performance analysis tools are lacking

In the case of the TL-WR1043nd, it can route 50Mbit/sec of tagged vlan traffic.    Running 'openssl speed' on the device is as expected, totally cpu-bound (100% user).   

Routing openvpn traffic however (with appropriate iptables rules for tun0/eth1) is maxed at about 500Kbyte/sec yet the cpu load never exceeds 25%.   

Running 'wget -O /dev/null <path to 4G vpn file>' directly on the TL-WR1043n is similarly maxed at about 500kbyte/sec transfer rate,   15% user,  6% system,  71% idle.             Equivalent for a non-vpn wget is 3Mbyte/sec  1% user 7% system.

Given that the MIPS 74Kc is integer only I expected to see the openvpn process consuming more resources for the traffic level.

(Last edited by crazybrit on 18 Apr 2014, 16:19)