• The GCC manual: http://gcc.gnu.org/onlinedocs/

  • "Code Optimization Using the GNU C Compiler," by Rahul U Joshi: http://www.linuxgazette.com/issue71/joshi.html

    This article describes some of the code optimization techniques used by the GNU C Compiler, in order to give the reader a feel of what code optimization is and how it can increase the efficiency of the generated object code.

  • Using and Porting GNU CC for Version 2.8, by Richard Stallman (Free Software Foundation). Also available online from http://www.delorie.com/gnu/docs/gcc/gcc_toc.html and many other locations.

  • Chapter 6 of the online book Securing and Optimizing Linux, RedHat Edition: A Hands on Guide talks extensively about compiler flags. It is located at http://www.linuxdoc.org/LDP/solrhe/Securing-Optimizing-Linux-RH-Edition-v1.3/gen-optim.html. The whole book (available in different formats) can be found at http://www.linuxdoc.org/guides.html#securing_linux.

  • More Apache and platform-specific performance-tuning notes can be found at http://httpd.apache.org/docs/misc/perf-tuning.html.