network performance

Stefan Lambrev stefan.lambrev at
Mon Feb 4 13:16:54 PST 2008

Andrew Thompson wrote:
> On Mon, Feb 04, 2008 at 05:26:35PM +0200, Stefan Lambrev wrote:
>> Greetings,
>> In my desire to increase network throughput, and to be able to handle more 
>> then ~250-270kpps
>> I started experimenting with lagg and link aggregation control protocol 
>> (lacp).
>> To my surprise this doesn't increase the amount of packets my server can 
>> handle
>> Using lagg doesn't improve situation at all, and also errors are not 
>> reported.
>> Also using lagg increased content switches:
>> Top showed for CPU states +55%   system, which is quite high?
>> I'll use hwpmc and lock_profiling to see where the kernel spends it's time.
> Thanks for investigating this. One thing to note is that ip flows from
> the same connection always go down the same interface, this is because
> Ethernet is not allowed to reorder frames. The hash uses
> src-mac, dst-mac, src-ip and dst-ip (see lagg_hashmbuf), make sure when
> performance testing that your traffic varies in these values. Adding
> tcp/udp ports to the hashing may help.
The traffic, that I generate is with random/spoofed src part, so it is 
split between interfaces for sure :)

Here you can find results when under load from hwpmc and lock_profiling:

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