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From: barnett@im4u.UUCP (Lewis Barnett @ home on the range)
Newsgroups: comp.unix.wizards
Subject: 4.3 Interlan driver receive routine
Message-ID: <1211@im4u.UUCP>
Date: Thu, 13-Nov-86 14:40:05 EST
Article-I.D.: im4u.1211
Posted: Thu Nov 13 14:40:05 1986
Date-Received: Thu, 13-Nov-86 21:50:40 EST
Organization: U. Texas CS Dept., Austin, Texas
Lines: 28
Keywords: Multiple receive buffers

About a week ago, I posted the following article.  It was during the
crossover period from net.unix-wizards to comp.unix.wizards, so it
might not have made it here.  So far, I have received only inquiries
from people who are interested in what I learn.
___________________________

I recently noticed that although the Interlan NI1010 Ethernet controller
has a large onboard receive buffer and a queue for sixteen pointers
to Unibus buffers for DMA ... the 4.3BSD driver (if_il.c) uses only
one Unibus buffer for packet reception.  I'm interested in increasing
the reception performance of the driver, and I wondered if anyone 
had considered extending the code to use more than one Unibus buffer.
I'd be interested in any information, from actual implementation
to mere musings.  If I receive sufficient response, I'll summarize.
____________________________

To add some context, I've written some network monitoring software
that uses the NI1010.  It keeps up pretty well up to around 12%
utilization, but starts losing a significant percentage of packets
at higher utilization.  Providing more buffers for DMA *should*
improve this performance, but I haven't completely succeeded in
my attempts to take advantage of this feature of the board.  Any
insights greatly appreciated.

Lewis Barnett,CS Dept, Painter Hall 3.28, Univ. of Texas, Austin, TX 78712

-- barnett@im4u.UTEXAS.EDU, barnett@im4u.UUCP,
      {ihnp4,harvard,seismo,gatech,ctvax}!im4u!barnett