Centos 7 (kernel 3.10) and GRE - a very low speed in the tunnel

[SergKz]

There is a border router on the basis of quite good (once Intel's server platform with Centos 7 installed on it.
Pumps of up to 1.5 gigabits, users shaping and routing towards the internal network. CPU usage is moderate.
Recently got an question to one subscriber needed a GRE tunnel.
He inexplicably slows shamelessly - more than 1.5 megabits does not accelerate in any way (looks by iperf).
Between the same points we raise ipip tunnel - get 80 megabits commercials, that is, on the whole hundred monthly.
Replace in commands to create a tunnel from "ipip" to "gre" - 1.5 megabits a maximum and an average of 800 kbps.
Gasim all shaping - flush all the rules of the tc - will not affect in any way.
Update centos to the last published updates - zero effect.
Conducted an experiment on a separate grid - put old tsentos 6.8 with the 2.6 kernel - all summer! in the same grid on the same piece of iron run centos 7 - the same brakes. Find kernel parameters, linked somehow to the protocol is the GRE, it has not yet succeeded.
What can I do in this case?

[neperpbl3]

Hello!
The problem is in the linux kernel. The problem with missing GRE packages in Linux arose in a certain version. Beginning with the kernel version 4.10.11-1 and higher the problem is solved.