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Date: Tue, 19 Apr 2005 17:42:09 -0400
From: Bosko Milekic <bmilekic@technokratis.com>
To: Eivind Hestnes <eivind@stabbursmoen.no>
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References: <20050419183335.F18008131@joshua.stabbursmoen.no>
	<42655887.7060203@alumni.rice.edu> <4265724A.1040705@stabbursmoen.no>
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cc: performance@freebsd.org
Subject: Re: Performance Intel Pro 1000 MT (PWLA8490MT)
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On Tue, Apr 19, 2005 at 11:04:10PM +0200, Eivind Hestnes wrote:
> It's correct that the card is plugged into a 32-bit 33 Mhz PCI slot. If 
> i'm not wrong, 33 Mhz PCI slots has a peak transfer rate of 133 MByte/s. 
> However, when pulling 180 mbit/s without the polling enabled the system 
> is very little responsive due to the interrupt load.  I'll try to 
> increase the polling frequency too see if this increases the bandwidth 
> with polling enabled.. Thanks for the advice btw..
> 
> - E.

   You are neglecting bus acquisition cycles as well as bus contention.
   Likely your 32-bit legacy PCI bus is shared between many devices.
   1Gbps for small packets is basically hopeless and you're probably
   stalling on the bus.

   Basically, a gigE card in a router you want to perform well in
   anything but a high-speed PCI-X bus (hopefully little or not
   contested) has been a terrible waste of money, in my experience.

-Bosko