ITK/Release 4/Wrapping/ccache

Using CCache for WrapITK

Using CCache[1] to build WrapITK can improve the build times considerably. For all unix systems (including MacOS X), ccache is enabled by creating symbolic links to the g++/gcc compiler:

ln -s /usr/bin/ccache /usr/local/bin/g++
ln -s /usr/bin/ccache /usr/local/bin/gcc

Alternatively, on MacOS X, Install ccache with Macports. The Macports installation would automatically create the symbolic links to g++/gcc compilers and put them in the directory /opt/local/libexec/ccache. The only remaining thing then is to add this directory to the PATH variable (alternatively you can add it to the .bash_profile or .profile in home directory)

$ sudo port install ccache
$ export PATH= /opt/local/libexec/ccache:$PATH

All the subsequent builds of WrapITK would use ccache and we can see a speedup of as much as 40 minutes for repeated invocations. For example, following lists the results for building WrapITK with & without ccache (for 8-core Quad-Core Intel Xeon with Mac OSX Snow Leopard):

Without cache:

time make -j 12
real      46m58.307s
user     41m49.829s
sys	      4m22.580s

Repeated invocation:

make clean
time make -j 12
real	     44m3.667s
user    39m29.606s
sys	     3m49.870s

On enabling ccache, the build times reduce considerably as noted below ""With cache:""

time make -j 12
real    45m44.488s
user   40m3.881s
sys	    4m25.381s
 
 ccache -s
 cache hit (direct)                    19
 cache hit (preprocessed)      1
 cache miss                              2658
 called for link                          396
 compile failed                         22 
 preprocessor error                 12
 no input file                              21
 files in cache                           5307
 cache size                                593.9 Mbytes
 max cache size                       1.0 Gbytes

Repeated invocation:

make clean
time make -j 12

real	    2m48.801s
user    1m28.743s
sys	    0m40.986s

ccache -s
cache hit (direct)                  2435
cache hit (preprocessed)    0
cache miss                             0
called for link                      152
files in cache                      5307
cache size                         593.9 Mbytes
max cache size                 1.0 Gbytes