Question

64

How do I set up ccache?

rated 0 times [ 64] [ 0] / answers: 1 / hits: 89015 / 1 Year ago, fri, november 18, 2022, 10:26:53

I want to use ccache to speed up compilation.

I came across How do I enable ccache?.

This is what I have done so far:

$ sudo apt-get install -y ccache

$ dpkg -l ccache

ii  ccache  3.1.6-1   Compiler cache for fast recompilation of C/C++ code

$ whereis ccache

ccache: /usr/bin/ccache /usr/lib/ccache /usr/bin/X11/ccache /usr/share/man/man1/ccache.1.gz

I appended ccache to the path by adding it to my ~/.bashrc file:

$ export PATH="/usr/lib/ccache:$PATH"

$ source ~/.bashrc

$ echo $PATH

/usr/lib/ccache:/usr/local/cuda-5.5/bin/:/usr/lib/lightdm/lightdm:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games

The symbolic links look fine:

$ ll /usr/lib/ccache/

total 76

drwxr-xr-x   2 root root  4096 mai   22 10:48 ./

drwxr-xr-x 253 root root 69632 mai   22 10:48 ../

lrwxrwxrwx   1 root root    16 mai   22 10:48 avr-g++ -> ../../bin/ccache*

lrwxrwxrwx   1 root root    16 mai   22 10:48 avr-gcc -> ../../bin/ccache*

lrwxrwxrwx   1 root root    16 mai   22 10:48 avr-gcc-4.5.3 -> ../../bin/ccache*

lrwxrwxrwx   1 root root    16 mai   22 10:48 c++ -> ../../bin/ccache*

lrwxrwxrwx   1 root root    16 mai   22 10:48 c89-gcc -> ../../bin/ccache*

lrwxrwxrwx   1 root root    16 mai   22 10:48 c99-gcc -> ../../bin/ccache*

lrwxrwxrwx   1 root root    16 mai   22 10:48 cc -> ../../bin/ccache*

lrwxrwxrwx   1 root root    16 mai   22 10:48 g++ -> ../../bin/ccache*

lrwxrwxrwx   1 root root    16 mai   22 10:48 g++-4.6 -> ../../bin/ccache*

lrwxrwxrwx   1 root root    16 mai   22 10:48 gcc -> ../../bin/ccache*

lrwxrwxrwx   1 root root    16 mai   22 10:48 gcc-4.6 -> ../../bin/ccache*

lrwxrwxrwx   1 root root    16 mai   22 10:48 x86_64-linux-gnu-g++ -> ../../bin/ccache*

lrwxrwxrwx   1 root root    16 mai   22 10:48 x86_64-linux-gnu-g++-4.6 -> ../../bin/ccache*

lrwxrwxrwx   1 root root    16 mai   22 10:48 x86_64-linux-gnu-gcc -> ../../bin/ccache*

lrwxrwxrwx   1 root root    16 mai   22 10:48 x86_64-linux-gnu-gcc-4.6 -> ../../bin/ccache*

The link looks good:

$ which g++

/usr/lib/ccache/g++



$ make

g++ -o affine_euler affine_euler.cpp -O3 -DEIGEN_NO_DEBUG -I/usr/include/eigen3

g++ -o test_eigen test_eigen.cpp -O3 -DEIGEN_NO_DEBUG -I/usr/include/eigen3

But the cache is empty:

$ ccache -s

cache directory                     /home/dell/.ccache

cache hit (direct)                     0

cache hit (preprocessed)               0

cache miss                             0

files in cache                         0

cache size                             0 Kbytes

max cache size                       1.0 Gbytes

Where am I wrong?

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brailloni

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answered 1 Year ago odyroc · Accepted Answer

Installation:

# Install package

sudo apt install -y ccache



# Update symlinks

sudo /usr/sbin/update-ccache-symlinks



# Prepend ccache into the PATH

echo 'export PATH="/usr/lib/ccache:$PATH"' | tee -a ~/.bashrc



# Source bashrc to test the new PATH

source ~/.bashrc && echo $PATH

Your path (at least the beginning) should look like:

/usr/lib/ccache:/usr/local/cuda-5.5/bin/:/usr/lib/lightdm/lightdm:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games

And g++/gcc should now point to:

which g++ gcc

/usr/lib/ccache/g++

/usr/lib/ccache/gcc

Configuration:

If you want no limit to the number of files and size of the cache:

ccache -F 0

ccache -M 0

Show cache statistics:

ccache -s

Empty the cache and reset the stats:

ccache -C -z

Usage:

Every time you call gcc or g++; ccache is called. My mistake was that I didn't delete already-compiled files. Just delete all your CMake/output files and configure/compile again.

Your ccache shouldn't be empty then. Now try a make clean and make and you'll see it is much faster than re-compiling everything thanks to the cache.