100 lines
4.0 KiB
Perl
100 lines
4.0 KiB
Perl
.\" Copyright (c) 1984 M. K. McKusick
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.\" Copyright (c) 1984 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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.\" @(#)4.t 1.2 (Berkeley) 11/8/90
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.\"
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.ds RH Conclusions
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.NH 1
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Conclusions
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.PP
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We have created a profiler that aids in the evaluation
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of the kernel.
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For each routine in the kernel,
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the profile shows the extent to which that routine
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helps support various abstractions,
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and how that routine uses other abstractions.
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The profile assesses the cost of routines
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at all levels of the kernel decomposition.
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The profiler is easily used,
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and can be compiled into the kernel.
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It adds only five to thirty percent execution overhead to the kernel
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being profiled,
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produces no additional output while the kernel is running
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and allows the kernel to be measured in its real environment.
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Kernel profiles can be used to identify bottlenecks in performance.
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We have shown how to improve performance
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by caching recently calculated name translations.
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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 35%.
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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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.nr H2 1
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.ds RH Acknowledgements
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.NH
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\s+2Acknowledgements\s0
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.PP
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I would like to thank Robert Elz for sharing his ideas and
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his code for cacheing system wide names.
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Thanks also to all the users at Berkeley who provided all the
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input to generate the kernel profiles.
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This work was supported by
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the Defense Advance Research Projects Agency (DoD) under
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Arpa Order No. 4031 monitored by Naval Electronic System Command under
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Contract No. N00039-82-C-0235.
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.ds RH References
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.nr H2 1
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.sp 2
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.NH
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\s+2References\s-2
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.LP
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.IP [Bentley81] 20
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Bentley, J. L.,
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``Writing Efficient Code'',
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Department of Computer Science,
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Carnegie-Mellon University,
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Pittsburgh, Pennsylvania,
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CMU-CS-81-116, 1981.
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.IP [Graham82] 20
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Graham, S., Kessler, P., McKusick, M.,
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``gprof: A Call Graph Execution Profiler'',
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Proceedings of the SIGPLAN '82 Symposium on Compiler Construction,
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Volume 17, Number 6, June 1982. pp 120-126
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.IP [Graham83] 20
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Graham, S., Kessler, P., McKusick, M.,
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``An Execution Profiler for Modular Programs''
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Software - Practice and Experience,
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Volume 13, 1983. pp 671-685
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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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