next_inactive up previous root


How Fast Can Windows Load a Lot of DLLs?

Gene Michael Stover

created Saturday, 2006 June 10
updated Sunday, 2006 August 13

Copyright © 2006 Gene Michael Stover. All rights reserved. Permission to copy, store, & view this document unmodified & in its entirety is granted.


Contents

1 What is this?

I was curious about how quickly Microsloth Winders can load a program that uses a lot of DLLs. So I wrote a Lisp program which writes DLL files & C programs that use them.

There probably isn't any practical use. I was just curious.

2 Running it yourself

Here's how to download & run the programs yourself:

  1. Download lotdll.zip to your Microsloth Windows computer.

  2. Unpack it into a directory of its own, such as C:\lotdll\.

  3. Use a command line or Windows Explorer to navigate into the bin directory of that lotdll directory.

  4. There are many programs in that bin directory. Most of them use some number of DLLs which are also in the directory. You can tell how many DLLs a program uses by the number in its name. For example, prog0010.exe uses ten of the DLLs, but prog1000.exe uses 1,000 of the DLLs.

    You can run those programs individually, but if you run go.exe, it will run all of them & display the times required for each.

The ZIP file also includes the source code.

3 The source code

``Source code'' can be an ill-defined term. I wrote three programs for this test: lotdll.lisp, go.c, & build.bat. The Lisp programs in lotdll.lisp generate a lot of C files & a Makefile. C files are commonly considered source code, but the ultimate source code for this project is in those three files I created by hand.

If you want to start from scratch with my three ultimate source code files, you must download them & place them in the appropriate directories. Here's the directory structure, plus links to the files.1

You must create the directory structure on your computer, then download the three files into it.

Then fire-up your favorite Lisp system. In Lisp, do this:

  1. (load "lotdll.lisp")

  2. (make-lotdll)

Back on the Microsloth Winders command line, edit build.bat, if necessary. Then run it: .\build.

When it's done, you'll have all the programs in the bin directory.

4 Conclusions

Figure 1: Results of running go.exe on my computer
\begin{figure}\begin{center} \begin{tabular}{\vert r\vert r\vert} \hline {\bf nu... ...ine 1,000 & $1.30 \times 10^1$\ \\ \hline \end{tabular}\end{center} \end{figure}

Figure 1 shows the results on my home Winders computer. My computer has Winders XP (home edition, methinks) running on a 1 GHz CPU with $\frac{1}{2}$ a gigabyte of real memory.

It looks like the cost is $O(N)$, maybe a little less, where $N$ is the number of DLLs your program uses. Every 100 DLLs your program uses adds about 1 second to the program's start-up time.

A. Other File Formats

Bibliography

next_inactive up previous root
Gene Michael Stover 2008-04-20