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

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

Am 20.06.2012 09:22, schrieb Eric Dumazet:

quoted

On Wed, 2012-06-20 at 09:00 +0200, Stefan Priebe - Profihost AG wrote:

quoted

Am 19.06.2012 23:31, schrieb Eric Dumazet:
Before:
http://pastebin.com/raw.php?i=1gVraWVc

After:
http://pastebin.com/raw.php?i=NSh8Y29s

You have a lot of packet losses

But this ONLY happens with tcp_timestamps=0.

Yes, you already told that in subject line.

single tcp flow ?

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.

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