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 7.5.4 How Compiling and Linking Affects the Speed of MySQL
 ----------------------------------------------------------
 
 Most of the following tests were performed on Linux with the MySQL
 benchmarks, but they should give some indication for other operating
 systems and workloads.
 
 You obtain the fastest executables when you link with -static.
 
 On Linux, it is best to compile the server with `pgcc' and -O3. You
 need about 200MB memory to compile `sql_yacc.cc' with these options,
 because `gcc' or `pgcc' needs a great deal of memory to make all
 functions inline. You should also set `CXX=gcc' when configuring MySQL
 to avoid inclusion of the `libstdc++' library, which is not needed. Note
 that with some versions of `pgcc', the resulting binary runs only on
 true Pentium processors, even if you use the compiler option indicating
 that you want the resulting code to work on all x586-type processors
 (such as AMD).
 
 By using a better compiler and compilation options, you can obtain a
 10-30% speed increase in applications. This is particularly important
 if you compile the MySQL server yourself.
 
 When we tested both the Cygnus CodeFusion and Fujitsu compilers,
 neither was sufficiently bug-free to allow MySQL to be compiled with
 optimizations enabled.
 
 The standard MySQL binary distributions are compiled with support for
 all character sets. When you compile MySQL yourself, you should include
 support only for the character sets that you are going to use. This is
 controlled by the -with-charset option to `configure'.
 
 Here is a list of some measurements that we have made:
 
    * If you use `pgcc' and compile everything with -O6, the `mysqld'
      server is 1% faster than with `gcc' 2.95.2.
 
    * If you link dynamically (without -static), the result is 13%
      slower on Linux. Note that you still can use a dynamically linked
      MySQL library for your client applications. It is the server that
      is most critical for performance.
 
    * For a connection from a client to a server running on the same
      host, if you connect using TCP/IP rather than a Unix socket file,
      performance is 7.5% slower. (On Unix, if you connect to the
      hostname `localhost', MySQL uses a socket file by default.)
 
    * For TCP/IP connections from a client to a server, connecting to a
      remote server on another host is 8-11% slower than connecting to a
      server on the same host, even for connections over 100Mb/s
      Ethernet.
 
    * When running our benchmark tests using secure connections (all
      data encrypted with internal SSL support) performance was 55%
      slower than with unencrypted connections.
 
    * If you compile with -with-debug=full, most queries are 20% slower.
      Some queries may take substantially longer; for example, the MySQL
      benchmarks run 35% slower. If you use -with-debug (without
      `=full'), the speed decrease is only 15%.  For a version of
      `mysqld' that has been compiled with -with-debug=full, you can
      disable memory checking at runtime by starting it with the
      -skip-safemalloc option. The execution speed should then be close
      to that obtained when configuring with -with-debug.
 
    * On a Sun UltraSPARC-IIe, a server compiled with Forte 5.0 is 4%
      faster than one compiled with `gcc' 3.2.
 
    * On a Sun UltraSPARC-IIe, a server compiled with Forte 5.0 is 4%
      faster in 32-bit mode than in 64-bit mode.
 
    * Compiling with `gcc' 2.95.2 for UltraSPARC with the -mcpu=v8
      -Wa,-xarch=v8plusa options gives 4% more performance.
 
    * On Solaris 2.5.1, MIT-pthreads is 8-12% slower than Solaris native
      threads on a single processor. With greater loads or more CPUs,
      the difference should be larger.
 
    * Compiling on Linux-x86 using `gcc' without frame pointers
      (-fomit-frame-pointer or -fomit-frame-pointer -ffixed-ebp) makes
      `mysqld' 1-4% faster.
 
 Binary MySQL distributions for Linux that are provided by MySQL AB used
 to be compiled with `pgcc'. We had to go back to regular `gcc' due to a
 bug in `pgcc' that would generate binaries that do not run on AMD. We
 will continue using `gcc' until that bug is resolved. In the meantime,
 if you have a non-AMD machine, you can build a faster binary by
 compiling with `pgcc'. The standard MySQL Linux binary is linked
 statically to make it faster and more portable.
 

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