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

Am 20.06.2012 11:28, schrieb Eric Dumazet:

On Wed, 2012-06-20 at 11:25 +0200, Stefan Priebe - Profihost AG wrote:

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Am 20.06.2012 11:17, schrieb Eric Dumazet:

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On Wed, 2012-06-20 at 11:12 +0200, Stefan Priebe - Profihost AG wrote:

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Am 20.06.2012 11:06, schrieb Stefan Priebe - Profihost AG:

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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.

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If you exchange sender/receiver role between linux kernel versions, is
it the same problem ?

I'm testing in both directions. So both are sending and receiving.

I've now made tests with only one sending an the other receiving.

When server B is the sender i get 4Gbit/s. When server A is the sender i
get full 9,9Gbit/s.

To rule out bad hardware, could you try a 3.5-rc3 kernel on B ?

Sure. In that case i get 4Gbit/s in both variants. I also tried two 
other different machines same result.

Stefan