Revision as of 21:21, 21 March 2009

Reorder code/data for libraries to improve file I/O

The comprehensive analysis of the cold start up behavior of OpenOffice.org shows that file I/O is main bottleneck. About 80% of the start up time is spent waiting for data from the disk. Most file I/O depends on library loading. This part describes what can be done to reduce I/O time for loading OpenOffice.org libraries. The main ideas are system independent but the solutions must be system/compiler specific. The following chapters describe in detail how we want to reorder code/data within the libraries.

Windows

This chapter describes the solution for the Windows platform.

Microsoft Visual Studio 2008

OpenOffice.org uses the Microsoft Visual Studio 2008 C/C++ compiler suite for the Windows build, called wntmsci12[.pro]. What options are available to support us reordering code/data in libraries? If you start the C/C++ compiler and linker with the help option you can see all supported options. The following section shows the options which can help us.

Microsoft (R) 32-Bit C/C++-Optimizing Compiler Version 15.00.30729.01 for 80x86
 
Copyright (C) Microsoft Corporation.  All rights reserved.
 
...
/Gh Enable _penter Hook Function
/GH Enable _pexit Hook Function
/Gy Enable Function-Level Linking
...
 
Microsoft (R) Incremental Linker Version 9.00.30729.01
Copyright (C) Microsoft Corporation.  All rights reserved.
 
 Syntax: LINK [Options] [Files] [@Commandfile]
 
   Options:
      ...
      /ORDER:@Filename
      ...

Determine what functions are called during start up

How to create an ORDER file that is accepted by the linker

Linux

MacOS X

The following web page from Apple describes what must be done to reorder code/data of a library to improvde locality.

Solaris