igb performance/load udp issue

[Jack Vogel]

I was fighting with UDP issues before the latest checkin, so you should
look at THAT version, 2.3.1 in HEAD please.

Jack


On Tue, Dec 20, 2011 at 5:52 PM, Clint <clint at servedomains.com> wrote:

> On Tue, 20 Dec 2011 14:48:14 -0800, YongHyeon PYUN wrote:
>
>> I also see similar excessive system load with em(4) on latest HEAD.
>> Self-clocking protocols like TCP does not seem to suffer from the
>> issue but UDP clearly shows the issue.  A single bulk UDP transmit
>> test session completely halts the box while the test is in
>> progress.  I have a patch that addresses it but it needs more clean
>> ups and Jack's review.  I'm not sure whether the patch could be
>> accepted since it completely removes taskqueue based approach in
>> TX/RX path.
>> Also note, multi-queue option of igb(4) can re-order UDP packets in
>> TX path such that it can result in poor NFS over UDP performance.
>> It seems TCP is more resilient on packet reodering though.
>>
>> Because igb(4) shares implementation idea with em(4), it's possible
>> igb(4) also have the similar issue.  I have to find some spare time
>> to try this with igb(4) but I'm somewhat overloaded to address poor
>> em(4) performance on 82574 with MSI-X.
>>
>>
> I decided to try the updated igb driver, v2.2.5, in FreeBSD 9.0RC3.  I can
> no longer duplicate the excessive load issue as it now performs so poorly
> that I can't even stream a 38Mbit/s file via either NFS/UDP or Samba/TCP,
> so things went from bad to worse.  I'm guessing it has something to do with
> flow control as that's appears to be different with this driver, back to
> v2.2.3 for now.
>
> Thanks,
> Clint
>
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