FYI, Just to help document the issue here. Using ccache on Linux can improve your compile time from a few minutes to a few seconds depending the use case.
On my machine Ubuntu 16.04 up to date as of 06/26/2016 using: sudo apt-get install ccache System Information: Model Name : Intel(R) Xeon(R) CPU E5-2699 v3 @ 2.30GHz sysname : Linux release : 4.4.0-24-generic version : #43-Ubuntu SMP Wed Jun 8 19:27:37 UTC 2016 machine : x86_64 CPU Information: nthreads : 2 ncores : 18 nsockets : 2 nbooks : 1 nlcores : 72 72 lcores, 2 socket(s), 18 cores per socket, 2 hyper-thread(s) per core Note: I have added the environment variable ?CCACHE_CPP2=yes Builds using DPDK 16.07-rc0 on 06/27/2016 Build with ?time CCACHE_DISABLE=true make install T=x86_64-native-linuxapp-clang? gives: real 2m52.844s user 2m32.220s sys 0m15.548s Rebuild with no changes, just issue the above line again: real 0m9.929s user 0m5.056s sys 0m3.036s If you issue the above line with ?j appended give: real 0m4.292s user 0m5.304s sys 0m4.348s remove x86_64-native-linuxapp-clang build directory. Build with ?time CCACHE_DISABLE=true make install T=x86_64-native-linuxapp-clang -j? gives: real 0m29.681s user 3m18.104s sys 0m34.876s cd x86_64-native-linuxapp-clang directory make clean time CCACHE_DISABLE=true make real 3m13.992s user 2m45.044s sys 0m21.784s make clean make # just to fill the ccache make clean time make real 0m15.066s user 0m6.776s sys 0m3.684s make clean time make ?j real 0m4.527s user 0m7.060s sys 0m5.428s As you can see the performance gain is very nice and I ccache does seem to work correctly except in a few cases. It appears the ccache and clang have a few problems without the global having the environment variable set: export CCACHE_CPP2=yes Without this environment variable clang starts to complain about a number of issues. If you see a compile problem please rebuild with ccache disabled using ?sudo CCACHE_DISABLE=true ?? or uninstall ccache ?sudo apt-get remove ccache? It is possible that GCC will also have compiler issues, but I do not seem to see any, just try without ccache to verify. Here is a link to help explain more details: See e.g. http://petereisentraut.blogspot.com/2011/09/ccache-and-clang-part-2.html If the build works then I have not found any issues with using ccache except a faster build time ? YMMV Regards, Keith
