SOLVED: Degraded TCP performace on Intel PRO/1000

[Kris Kennaway]

On Fri, May 06, 2005 at 08:59:50AM +0200, Marian Durkovic wrote:
> Hi all,
> 
> 
>   seems we've found the problem. The performance degradation was happening
> it the TX path, due to insufficient setting of TX packet buffer FIFO on the
> chip.
> 
>   To achieve wirespeed performance, the TX FIFO must be large enough to
> accomodate 2 jumbo packets (not just 1 as the driver was assuming).
> There was also a typo in the driver, causing the PBA tuning on most
> cards to be non-functional.
> 
>   Due to above limitation, the 82547 chipset (featuring only 40 KB of 
> RX/TX FIFO) only supports wirespeed tranfers upto 8 KB TCP payload
> (MTU 9000 bytes).
> 
>   Please be sure to use em driver version 1.7.41 or newer, either from
> the CVS (branch RELENG_4_11) or from Intel's downloads.

Does this also apply to 5.x and above?  If no-one else responds in the
next few days, can you please submit the patch in PR so it does not
get lost?

Kris
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