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Performance Interactions Between P-HTTP and TCP Implementations

John Heidemann
USC/Information Sciences Institute

Abstract

This document describes several performance problems resulting from interactions between implementations of persistent-HTTP (P-HTTP) and TCP. Two of these problems tie P-HTTP performance to TCP delayed-acknowledgments, thus adding up to 200ms to each P-HTTP transaction. A third results in multiple slow-starts per TCP connection. Unresolved, these problems result in P-HTTP transactions which are 14 times slower than standard HTTP and 20 times slower than potential P-HTTP over a 10 Mb/s Ethernet. We describe each problem and potential solutions. After implementing our solutions to two of the problems, we observe that P-HTTP performs better than HTTP on a local Ethernet. Although we observed these problems in specific implementations of HTTP and TCP (Apache-1.1b4 and SunOS 4.1.3, respectively), we believe that these problems occur more widely.

Availability

This paper is available in several formats: abstract web page with pointers and cites, gzip'ed postscript, PDF, http://www.isi.edu/lsam/publications/phttp_tcp_interactions/>">gzip'ed postscript, paper copies can be obtained by mail to the authors. Copyright terms for this paper appear below.

Reference

Heidemann97a: John Heidemann. Performance Interactions Between P-HTTP and TCP Implementations. ACM Computer Communication Review, 27 (2 ), pp. 65-73, April, 1997. <http://www.isi.edu/~johnh/PAPERS/Heidemann97a.html>.

@article{Heidemann97a,
	author = "John Heidemann",
	title = "Performance Interactions Between {P-HTTP} and
                        {TCP} Implementations",
	journal = "{ACM} Computer Communication Review",
	year = "1997",
	volume = "27",
	number = "2",
	month = "April",
	pages = "65--73",
	Xnote = "Draft versions were available in 1996 as [Heidemann96b]",
	keywords = "http, apache, bsd-tcp, nagle's algorithm",
	url = "http://www.isi.edu/~johnh/PAPERS/Heidemann97a.html",
	psurl = "http://www.isi.edu/~johnh/PAPERS/Heidemann97a.ps.gz",
	pdfurl = "http://www.isi.edu/~johnh/PAPERS/Heidemann97a.pdf",
	htmlurl = "http://www.isi.edu/lsam/publications/phttp_tcp_interactions/",
	organization = "USC/Information Sciences Institute",
	copyrightholder = "author",
}

Copyright

This paper is copyright © 1997 by its authors. Permission to make digital or hard copies of part or all of this work for personal use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that new copies bear this notice and the full citation on the first page. Abstracting with credit is permitted.

To copy otherwise, to republish, to post on servers or to redistribute to lists, requires prior specific permission of the authors.