Subject: Re: unstable 10GBE performance with recent kernels (> 3.0.X)

From: Stefan Priebe - Profihost AG <[email-masked]>
Date: Mon, 18 Jun 2012 16:17:15 +0200

Am 18.06.2012 15:29, schrieb Eric Dumazet:
>> But with the latest long term stable vanilla kernel 3.0.34.
>>
>> # iperf -c HOST -t 60
>>
>> works fine but with -d for using both directions i see around 9.8Gbit/s
>> in one direction and only 300kb/s in the other direction.
>
> I would try using regular MTU.
For 3.5.0-rc2 this works fine but decreases the speed from 9,9Gbit/s to 
9,3Gbit/s. With mtu 9000 i get around 3-4Gbit/s (netstat -s attached below)

With 3.0.34 MTU 9000 works fine with constant 9,9Gbit/s in both directions.

> And post "netstat -s" results before/after your iperf.

Tests with mtu 9000 and 3.5rc2:
Pre: http://pastebin.com/raw.php?i=uBjsFKjs
Post: http://pastebin.com/raw.php?i=TAK8JS6j

Thanks again!

Stefan