Measurement, Analysis and Performance Improvement of the Apache Web Server
Description
Performance of Web servers is critical to the success of many
corporations and organizations. However, very few results have been
published that quantitatively study the server behavior and identify
the performance bottlenecks. In this paper we measure and analyze the
behavior of the popular Apache Web server on a uniprocessor system and
a 4-CPU SMP (Symmetric Multi-Processor) system running the IBM AIX
operating system. Using the AIX
built-in tracing facility and a trace-analysis tool, we obtained
detailed information on OS kernel events and overall system activities
while running Apache driven by the SPECweb96 and the WebStone
benchmarks. We found that on average, Apache spends about 20-25% of
the total CPU time on user code, 35-50% on kernel system calls and
25-40% on interrupt handling. For systems with small RAM sizes, the
Web server performance is limited by the disk bandwidth. For systems
with reasonably large RAM sizes, the TCP/IP stack and the network
interrupt handler are the major performance bottlenecks.
We notice that Apache shows similar
behavior on both the uniprocessor and the SMP systems.
After quantitatively identifying the performance bottlenecks, we
proposed 8 techniques to improve the performance of Apache. We
implemented all but one of these techniques. Our experimental results
show that these techniques improve the throughput of Apache by 61%.
These techniques are general purpose and can be applied to other
Web servers as well.
Finally, our results suggest that operating system support for
directly sending data from the file system cache to the TCP/IP network
can further improve the Web server performance dramatically.
Publications
Yiming Hu, Ashwini Nanda and Qing Yang,
Measurement, Analysis and Performance Improvement of the Apache Web Server.
To be presented in
the 18th IEEE International Performance, Computing and Communications Conference (IPCCC'99),
Phoenix/Scottsdale, Arizona, February 1999.
Download the
full IPCCC'99 paper (IEEE Copyrighted) (154 KB gzipped PS file).
Yiming Hu, Ashwini Nanda and Qing Yang,
Measurement, Analysis and Performance Improvement of the Apache Web Server.
Technical Report No. 1097-0001, Dept. of Electrical and Computer Engineering,
University of Rhode Island, Nov. 1998. This is an expended version of
the above IPCCC'99 paper.
Download the the
full report (164 KB gzipped PS file).
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this work in other works must be obtained from the IEEE.
Funding
IBM and NSF
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