CCACHE

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CCACHE is an application that caches compilation results and reuses it in future compilations in order to achieve faster compile times. This short tutorial will show you how to use it on your system.

Note: CCACHE can cause build failures. If it does, please try to compile the application without CCACHE enabled. Bug reports reported with CCACHE enabled will be closed.

Contents

Installing CCACHE

To emerge dev-util/ccache, run the following:

# emerge ccache

Once it finishes emerging, enable it in portage. This is very easy. Just open up /etc/portage/make.conf with your favorite text editor and add the following:

FEATURES="ccache"

That's it. If you want to check how much the cache is taking up on your disk and other info, you can run the following command:

# CCACHE_DIR="/var/tmp/ccache" ccache -s

You must pass the CCACHE_DIR option since ccache normally defaults to the user's home directory, and portage uses /var/tmp/ccache.

Tweaking CCACHE

Disabling the CACHE limit

If you want to let the cache have the flexibility to grow to whatever size it needs to (unlimited size cache), just do the following:

# CCACHE_DIR="/var/tmp/ccache" ccache -M 0

This will let the cache grow to whatever size it needs to grow to over time.

Tricks

Using CCACHE to compile your kernel faster

In order to do this you need to change a few variables, you probably only want to change these variables temporarily, but you could change them permanently if you want to. Since we just want to do this temporarily for this example, make a new file called build.sh and put the following inside of it:

#!/bin/bash

export CCACHE_DIR="/var/tmp/ccache"
export PATH="/usr/lib/ccache/bin:${PATH}"

cd /usr/src/linux
time make bzImage modules

Give the file execute permission:

# chmod u+x build.sh

This will temporarily export the variables neccessary, then go into the /usr/src/linux folder (whatever you declared with 'eselect kernel') and then compile the kernel.