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From John Heidemann <jo...@ISI.EDU>
Subject performance ``bugs'' in apache-1.1b4's P-HTTP
Date Wed, 10 Jul 1996 20:50:38 GMT

I've found a couple of interactions between Apache-1.1b4's P-HTTP and
SunOS TCP that significantly reduce performance.  A web page
summarizing the problems and containing patches resolving them is now
available at
<>.  (The
abstract of the web page is attached below.

I encourage the Apache core team to look at these problems and
proposed solutions.  If you agree with the analysis,
then the patches (or their equivalents) should be added to a future
Apache release.

   -John Heidemann


Performance Interactions Between P-HTTP and TCP Implementations
John Heidemann
10 July 1996


This document summarizes several performance problems resulting from
interactions between the Apache-1.1b4 implementation of
persistent-HTTP (P-HTTP) and BSD-based implementations of TCP. Two of
these problems tie P-HTTP performance to TCP delayed-acknowledgments,
thus adding up to 200ms to each P-HTTP transaction. We discuss each
problem and summarize solutions. Unresolved, these problems result in
P-HTTP transactions which are 10 times slower than standard HTTP and
20 times slower than potential P-HTTP for machines connected by a 10
Mbps Ethernet. After fixing these problems we observe that P-HTTP
succesfully performs better than HTTP on a local Ethernet.

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