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From: Don Lewis <Don.Lewis@tsc.tdk.com>
Message-Id: <199711040147.RAA10391@salsa.gv.tsc.tdk.com>
Date: Mon, 3 Nov 1997 17:47:47 -0800
In-Reply-To: Simon Shapiro <Shimon@i-Connect.Net>
       "Re: de0 errors" (Nov  3,  5:15pm)
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To: Simon Shapiro <Shimon@i-Connect.Net>, Don Lewis <Don.Lewis@tsc.tdk.com>
Subject: Re: de0 errors
Cc: freebsd-hackers@FreeBSD.ORG, Jaye Mathisen <mrcpu@cdsnet.net>,
        Matt Thomas <matt@3am-software.com>,
        Charles Henrich <henrich@crh.cl.msu.edu>
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On Nov 3,  5:15pm, Simon Shapiro wrote:
} Subject: Re: de0 errors
} 
} Hi Don Lewis;  On 04-Nov-97 you wrote: 
} 
} ...
} 
} >  } Humm, tcpblast shows 4.0MB/sec.  Granted this isnt an empty net
} >  either, fairly
} >  } busy I would imagine.  
} >  
} >  That's probably a reasonable number for a 10Mb network, but not a
} >  100Mb network.  BTW, I bet this NIC is also hurting your disk I/O
} >  throughput since it is hogging the PCI bus because it's using an
} >  inefficient transfer method.
} 
} I must be missing something.  4MB/sec. on TCP/IP over Ethernet is on a good
} day, more than 40MHz.  No?

You're not missing anything, I slipped a decimal point.  Sigh ...

BTW, I just did some quick calculations and a 21140 + 440FX might still
be able to drive the network at full speed without running out of PCI
bandwidth.  It's just that if you're transmitting, you'll consume about
4x the transmit bandwidth on the PCI bus.  If you're able to send at
10MB/sec, then you'll consume about 40MB/sec on the PCI bus out of the
theoretical 132MB/sec.

			---  Truck