Improving program startup with fastbind [HP-UX Linker] White paper

ManualsBrandsHP ManualsSoftwareHP-UX Migration and Transition Tools

Abstract.............................................................................................................................................. 2

Intended audience ............................................................................................................................... 2

Terms and definitions ........................................................................................................................... 2

Prerequisites........................................................................................................................................ 2

Related information .............................................................................................................................. 2

Working of fastbind ............................................................................................................................. 4

Using prebind ..................................................................................................................................... 6

For more information............................................................................................................................ 8

Improving program startup with fastbind

[HP-UX Linker] White paper

Summary of content (8 pages)

PAGE 1
Improving program startup with fastbind : [HP-UX Linker] White paper Abstract .............................................................................................................................................. 2 Intended audience ............................................................................................................................... 2 Terms and definitions ......................................................................................................................
PAGE 2
Abstract On HP-UX Integrity, all application programs are linked to shared libraries. During the startup of each such program, the dynamic loader spends a significant amount of time in searching symbols. This document describes a way to avoid this cost and improve program startup performance using the fastbind(1) and prebind(1) tools. Intended audience This document is intended for developers and users (including system administrators) of applications on HP-UX Integrity systems.
PAGE 3
Introduction On HP-UX Integrity, programs are always linked to shared libraries as system libraries are not delivered in archive form. Every application program is an “incomplete executable” that depends on many shared libraries for its functioning. An incomplete executable or a shared library is a “load module”. In loading a shared library, the dynamic loader goes through the following sequence: 1. Searching and loading the shared library – mapping the text and data segments into memory. 2.
PAGE 4
It can be seen that most of the startup time is being spent in applying relocations. The fastbind(1) tool helps avoid this startup overhead. It caches the results of the symbol search, so that the dynamic loader can use the cached results directly during subsequent runs. Working of fastbind The working of fastbind is as follows: 1. fastbind invokes a dry run of the program and sends the appropriate options to the dynamic loader (to put it in “fastbind mode”). 2.
PAGE 5
Figure 2: Sample run of fastbind # fastbind /usr/bin/ls # fastbind /opt/mozilla/mozilla-bin fastbind: Unable to find library 'libmozjs.sl'. # LD_LIBRARY_PATH=/opt/mozilla fastbind /opt/mozilla/mozilla-bin # Figure 3 shows the new startup times for mozilla after using fastbind. in. As can be seen, the time spent in processing startup relocations has been cut down by half. Figure 3: Time spent in dynamic loader at startup after using fastbind.
PAGE 6
Using prebind The fastbind tool only modifies the executable and does not modify the software product information with the latest file metadata. Hence, causing a mismatch between the executable and the updated software product. Under these circumstances, the prebind(1) tool can be used to accomplish both tasks - of running fastbind on the executable and updating the software product.
PAGE 7
Figure 4: Sample run of prebind #prebind called without any executables # prebind #prebind with executables mentioned in the command line # prebind /opt/mozilla/mozilla-bin prebind: fastbind error: fastbind: Unable to find library 'libmozjs.sl'. # LD_LIBRARY_PATH=/opt/mozilla prebind /opt/mozilla/mozilla-bin # cat prebind.conf /usr/ccs/bin/rehash /usr/local/bin/vim #prebind command used to preview the undo mode with executable path supplied in a file # ./prebind -u -p -f prebind.
PAGE 8
For more information http://www.hp.com/go/linker © Copyright 2009 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice. The only warranties for HP products and services are set forth in the express warranty statements accompanying such products and services. Nothing herein should be construed as constituting an additional warranty. HP shall not be liable for technical or editorial errors or omissions contained herein. Linux is a U.S.