Path: utzoo!utgpu!utcsri!me!oldhub!thomson
From: thomson@oldhub.toronto.edu (Brian Thomson)
Newsgroups: comp.protocols.tcp-ip
Subject: Re: maximum Ethernet throughput
Message-ID: <753@oldhub.toronto.edu>
Date: 17 Mar 88 03:48:09 GMT
Article-I.D.: oldhub.753
Posted: Wed Mar 16 22:48:09 1988
References: <8803100345.AA09833@lbl-csam.arpa>
Reply-To: thomson@hub.toronto.edu (Brian Thomson)
Distribution: world
Organization: CSRI, University of Toronto
Lines: 19



Van Jacobson's results are certainly startling, but I can't help
believing that a significant part of that speedup must be in
changes to the mbuf handling, the socket code, and the LANCE
driver.  My evidence is a test I ran on a 3/50: I defined a
'protocol' whose PRU_SEND action was to checksum each mbuf then
hand it directly to the driver, with a dummy AF_UNSPEC destination so
there would be no ARPing going on.  This exercises vanilla
SUN mbuf, socket, and interface driver code, while replacing all
of TCP/IP by simple checksumming - so no protocols at all.
The data goes nowhere, and there are no acks to deal with.
Even so, this configuration could not source data to the wire faster
than about 3.6Mb/sec.  I could hit 8Mb/sec if I threw the data
away right after checksumming, without passing it to the driver at all.

-- 
		    Brian Thomson,	    CSRI Univ. of Toronto
		    utcsri!uthub!thomson, thomson@hub.toronto.edu