165 lines
6.6 KiB
Perl
165 lines
6.6 KiB
Perl
.\" Copyright (c) 1985 The Regents of the University of California.
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)7.t 5.1 (Berkeley) 4/17/91
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.\"
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.ds RH Conclusions
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.NH
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Conclusions
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.PP
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4.2BSD, while functionally superior to 4.1BSD, lacked much of the
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performance tuning required of a good system. We found that
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the distributed system spent 10-20% more time in the kernel than
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4.1BSD. This added overhead combined with problems with several
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user programs severely limited the overall performance of the
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system in a general timesharing environment.
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.PP
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Changes made to the system since the 4.2BSD distribution have
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eliminated most of the
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added system overhead by replacing old algorithms
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or introducing additional cacheing schemes.
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The combined caches added to the name translation process
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reduce the average cost of translating a pathname to an inode by more than 50%.
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These changes reduce the percentage of time spent running
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in the system by nearly 9%.
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.PP
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The use of silo input on terminal ports only when necessary
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has allowed the system to avoid a large amount of software interrupt
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processing. Observations show that the system is forced to
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field about 25% fewer interrupts than before.
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.PP
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The kernel
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changes, combined with many bug fixes, make the system much more
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responsive in a general timesharing environment.
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The 4.3BSD Berkeley UNIX system now appears
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capable of supporting loads at least as large as those supported under
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4.1BSD while providing all the new interprocess communication, networking,
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and file system facilities.
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.nr H2 1
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.ds RH Acknowledgements
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.SH
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\s+2Acknowledgements\s0
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.PP
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We would like to thank Robert Elz for sharing his ideas and
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his code for cacheing system wide names and searching the process table.
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We thank Alan Smith for initially suggesting the use of a
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capability based cache.
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We also acknowledge
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George Goble who dropped many of our changes
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into his production system and reported back fixes to the
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disasters that they caused.
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The buffer cache read-ahead trace package was based
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on a program written by Jim Lawson. Ralph Campbell
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implemented several of the C library changes. The original
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version of the Internet daemon was written by Bill Joy.
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In addition,
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we would like to thank the many other people that contributed
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ideas, information, and work while the system was undergoing change.
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.ds RH References
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.nr H2 1
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.sp 2
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.SH
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\s+2References\s-2
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.LP
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.IP [Cabrera84] 20
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Luis Felipe Cabrera, Eduard Hunter, Michael J. Karels, and David Mosher,
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``A User-Process Oriented Performance Study of Ethernet Networking Under
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Berkeley UNIX 4.2BSD,''
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Research Report No. UCB/CSD 84/217, University of California,
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Berkeley, December 1984.
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.IP [Cabrera85] 20
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Luis Felipe Cabrera, Michael J. Karels, and David Mosher,
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``The Impact of Buffer Management on Networking Software Performance
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in Berkeley UNIX 4.2BSD: A Case Study,''
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Proceedings of the Summer Usenix Conference, Portland, Oregon,
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June 1985, pp. 507-517.
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.IP [GADS85] 20
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GADS (Gateway Algorithms and Data Structures Task Force),
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``Toward an Internet Standard for Subnetting,'' RFC-940,
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Network Information Center, SRI International,
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April 1985.
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.IP [Joy80] 20
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Joy, William,
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``Comments on the performance of UNIX on the VAX'',
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Computer System Research Group, U.C. Berkeley.
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April 1980.
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.IP [Kashtan80] 20
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Kashtan, David L.,
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``UNIX and VMS, Some Performance Comparisons'',
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SRI International. February 1980.
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.IP [Lankford84] 20
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Jeffrey Lankford,
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``UNIX System V and 4BSD Performance,''
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\fIProceedings of the Salt Lake City Usenix Conference\fP,
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pp 228-236, June 1984.
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.IP [Leffler84] 20
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Sam Leffler, Mike Karels, and M. Kirk McKusick,
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``Measuring and Improving the Performance of 4.2BSD,''
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\fIProceedings of the Salt Lake City Usenix Conference\fP,
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pp 237-252, June 1984.
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.IP [McKusick85]
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M. Kirk McKusick, Mike Karels, and Samual Leffler,
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``Performance Improvements and Functional Enhancements in 4.3BSD''
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\fIProceedings of the Portland Usenix Conference\fP,
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pp 519-531, June 1985.
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.IP [Mockapetris83] 20
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Paul Mockapetris, ``Domain Names \- Implementation and Schedule,''
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Network Information Center, SRI International,
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RFC-883,
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November 1983.
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.IP [Mogul84] 20
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Jeffrey Mogul, ``Broadcasting Internet Datagrams,'' RFC-919,
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Network Information Center, SRI International,
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October 1984.
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.IP [Mosher80] 20
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Mosher, David,
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``UNIX Performance, an Introspection'',
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Presented at the Boulder, Colorado Usenix Conference, January 1980.
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Copies of the paper are available from
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Computer System Research Group, U.C. Berkeley.
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.IP [Nagle84] 20
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John Nagle, ``Congestion Control in IP/TCP Internetworks,'' RFC-896,
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Network Information Center, SRI International,
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January 1984.
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.IP [Ritchie74] 20
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Ritchie, D. M. and Thompson, K.,
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``The UNIX Time-Sharing System'',
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CACM 17, 7. July 1974. pp 365-375
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.IP [Shannon83] 20
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Shannon, W.,
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private communication,
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July 1983
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.IP [Walsh84] 20
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Robert Walsh and Robert Gurwitz,
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``Converting BBN TCP/IP to 4.2BSD,''
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\fIProceedings of the Salt Lake City Usenix Conference\fP,
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pp 52-61, June 1984.
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