Igb driver - header split feature

[Rafael Ganascim]

We have a lot of small packets passing through the FreeBSD firewall
(~1000 concurrent IP Phones (with 10ms voice payload)  speaking at
same time plus 'LAN' traffic)....

I'll test and report the results. I think that the feature can help on
this case.

Thanks.

Em 29 de fevereiro de 2012 19:17, Jack Vogel <jfvogel at gmail.com> escreveu:
> It seems to help in some workloads, makes little difference in others, and
> can even be
> less performance in yet others. Its just not a feature that is a 100% win,
> that's why its
> not on by default. Try it and see.
>
> Cheers,
>
> Jack
>
>
> On Wed, Feb 29, 2012 at 5:10 AM, Rafael Ganascim <rganascim at gmail.com>
> wrote:
>>
>> Hi list,
>>
>> I was looking in the igb driver that I use on some Intel nics
>> (dualport and quadport gigabit) and in the source code, the feature:
>>
>> /*
>> ** Header split causes the packet header to
>> ** be dma'd to a seperate mbuf from the payload.
>> ** this can have memory alignment benefits. But
>> ** another plus is that small packets often fit
>> ** into the header and thus use no cluster. Its
>> ** a very workload dependent type feature.
>> */
>>
>> Somebody is using this feature? What's the results?
>>
>> I think that this feature can be helpfull to improve the performance,
>> allowing the processing of the packet headers more fastest (pfills,
>> routing, etc). Is this true?
>>
>> Thanks in advance.
>>
>> Rafael
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>