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Date:      Sun, 21 Jun 2009 19:34:19 -0400
From:      Sergey Babkin <babkin@verizon.net>
To:        Wojciech Puchar <wojtek@wojtek.tensor.gdynia.pl>
Cc:        Dag-Erling =?iso-8859-1?Q?Sm=F8rgrav?= <des@des.no>, freebsd-hackers@freebsd.org
Subject:   Re: is RTL8139 THAT bad?
Message-ID:  <4A3EC37B.F589EA09@verizon.net>
References:  <alpine.BSF.2.00.0906211709420.1184@wojtek.tensor.gdynia.pl> <86eitdy4hl.fsf@ds4.des.no> <alpine.BSF.2.00.0906212219190.77226@wojtek.tensor.gdynia.pl>

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Wojciech Puchar wrote:
> 
> > Wojciech Puchar <wojtek@wojtek.tensor.gdynia.pl> writes:
> >> Why it's THAT bad?
> >
> > http://svn.freebsd.org/base/head/sys/pci/if_rl.c
> >
> > Scroll down past the copyright, license and attribution.  Read the
> > 38-line comment that explains just how crappy this chip really is.
> 
> Well - really "low end".
> 
> But - this computer can do memcpy at 80MB/s, so at 3.5MB/s it should be 5%
> CPU for memcpy, and one interrupt per one packet (2500 packets/s).
> 
> Is something more that make it consume >50% CPU?

Accessing the on-card memory through PCI is guaranteed to be
slower than the main memory, and depending on the particular
card it may be much slower.

-SB



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