Re: 10GBE performance drop with net.ipv4.tcp_timestamps=0

Am 20.06.2012 10:41, schrieb Eric Dumazet:

On Wed, 2012-06-20 at 10:21 +0200, Stefan Priebe - Profihost AG wrote:

quoted

Am 20.06.2012 09:22, schrieb Eric Dumazet:

Yes, you already told that in subject line.

single tcp flow ?

I use iperf - i think it uses just a single tcp flow. But i'm not sure.

You seem to have a switch or something that drops packets in this case.
You could try to rate limit to 9Gb/s and see if it is better.

Sadly i can't rate limit to 9Gbit/s on the switch.

Here, I roughly have same bandwidth with tcp_timestamps on or off, with
ixgbe cards and net-next kernels.

Mhm strange. Do you have any vague idea what could cause this? Any wrong 
reordering of the packets without tcp_timestamps?

Stefan