Hi Gert
On Sat, Aug 22, 2015, at 12:57 PM, Gert Doering wrote:
> Jan Just is wondering since years why OpenVPN is "slow", but he's talking
> about "getting only 600Mbit out of a Gbit link" or such :-)
That would be nice!
> > 18M->15.5M is ~ a 14% slowdown. I don't know if that's as good as it gets
> > or if more can be done.
>
> If it was my link, I would be happy with that and focus on other things :-)
That's the advice and experience I was looking for.
> IPSEC can go to higher speeds if done right because it's done in the kernel,
The "if done right" part is the part that worried me. The OpenVpn docs are the
Encyclopedia Britannica by comparison
(For the young folks, Encyclopedia Britannica is just Wikipedia on paper with
better spelling and grammar!)
> so no "copy packet to userland process, encapsulate, copy it back to kernel
> space, send out" - but that's again talking about gbit ranges, not about
> ~20 Mbit/s
>
> > I guess if there was hardware encryption in the loop, probably needed on
> > both ends?, then that may improve.
>
> Hardware encryption will reduce the CPU needed to achieve your throughput,
> but since the CPU is not 100% utilized, I don't think it will make it
> go faster. Bottleneck is not the CPU.
Re: CPU, I started a 1 GB download over IPv6 to my LAN. So the traffic is all
over the Vpn link.
Checking 'top' on the Atom in the middle of it, OpenVpn is the top CPU user,
but never climbs above 20%.
top - 13:00:23 up 20:21, 1 user, load average: 0.27, 0.09, 0.07
Tasks: 146 total, 2 running, 144 sleeping, 0 stopped, 0 zombie
%Cpu(s): 1.0 us, 1.3 sy, 0.0 ni, 95.0 id, 0.0 wa, 0.0 hi, 2.7 si, 0.0 st
KiB Mem: 2823048 total, 2237488 used, 585560 free, 1236944 buffers
KiB Swap: 4194300 total, 380 used, 4193920 free. 827948 cached Mem
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
25134 root 20 0 56204 6360 5344 S 19.25 0.225 0:10.59 openvpn
...
I could probably use my RaspberryPi2 ...
> - "it works and protects my packets" :-)
Which is kind of where I'm landing.
Thanks!
- John
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