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Date:   Thu, 16 Mar 2017 20:05:20 -0700
From:   Alexander Duyck <>
To:     Ben Greear <>
Cc:     e1000-devel list <>,
        netdev <>
Subject: Re: Performance issue with igb with lots of different src-ip addrs.

I'm not really interested in installing a custom version of pktgen.
Any chance you can recreate the issue with standard pktgen?

You might try running perf to get a snapshot of what is using CPU time
on the system.  It will probably give you a pretty good idea where the
code is that is eating up all your CPU time.

- Alex

On Thu, Mar 16, 2017 at 7:46 PM, Ben Greear <> wrote:
> I'm actually using a hacked up version of pktgen nicely driven by our
> GUI tool, but the crux is that you need to set min and max src IP to some
> large
> range.
> We are driving pktgen from a separate machine.  Stock pktgen isn't good at
> reporting
> received pkts last I checked, so it may be more difficult to easily view the
> problem.
> I'll be happy to set up my tool on your Fedora 24 or similar VM or machine
> if you
> want.
> Thanks,
> Ben
> On 03/16/2017 07:35 PM, Alexander Duyck wrote:
>> Can you include the pktgen script you are running?
>> Also when you say you are driving traffic through the bridge are you
>> sending from something external on the system or are you actually
>> directing the traffic from pktgen into the bridge directly?
>> - Alex
>> On Thu, Mar 16, 2017 at 3:49 PM, Ben Greear <>
>> wrote:
>>> Hello,
>>> We notice that when using two igb ports as a bridge, if we use pktgen to
>>> drive traffic through the bridge and randomize (or use a very large
>>> range)
>>> for the source IP addr in pktgen, then performance of igb is very poor
>>> (like
>>> 150Mbps
>>> throughput instead of 1Gbps).  It runs right at line speed if we use same
>>> src/dest
>>> IP addr in pktgen.  So, seems it is related to lots of src/dest IP
>>> addresses.
>>> We see same problem when using pktgen to send to itself, and we see this
>>> in
>>> several different kernels.  We specifically tested bridge mode in this
>>> stock
>>> Fedora kernel:
>>>  Linux lfo350-59cc 4.9.13-101.fc24.x86_64 #1 SMP Tue Mar 7 23:48:32 UTC
>>> 2017
>>> x86_64 x86_64 x86_64 GNU/Linux
>>> e1000e does not show this problem in our testing.
>>> Any ideas what the issue might be and how to fix it?
>>> Thanks,
>>> Ben
>>> --
>>> Ben Greear <>
>>> Candela Technologies Inc
> --
> Ben Greear <>
> Candela Technologies Inc

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