New comment by pullmoll on void-packages repository https://github.com/void-linux/void-packages/issues/26508#issuecomment-730645253 Comment: 1) You probably cannot expect a single hit between chromium-86 and chromium-87 because headers changed and a change in a central header (think `version.h`) prevents a cache hit. 2) You need to make sure to re-bootstrap your environment, i.e. do `./xbps-src zap` and `./xbps-src binary-bootstrap` again to make the `etc/conf` (not `etc/config` AFAICT) change take effect. 3) Any change in the compiler binary invalidates the entire current cache, because a checksum of the compiler binary (`/usr/bin/clang++` in this case) is used to make sure that compilation results will indeed be identical. So the update of llvm10 to llvm11 already invalidated all your existing cache entries for `clang` / `clang++`. You can clean and zap the cache (`ccache -C` and `ccache -Z`) in such a case, except perhaps if you also have lots of `gcc` and `g++` cache entries. I have a separate 1TB SSD for ccache and currently have 653 GiB of 768 GiB used with a cache hit rate of 8.06%. I'm building literally tens of thousands of packages for all architectures and can confirm that `ccache` indeed works as it is supposed to. Just to show you the figures this is the output of `ccache -s`. In my user's environment I have `CCACHE_DIR=/work/void/ccache` i.e. the same directory which is used from inside the chroot: ``` cache directory /work/void/ccache primary config /work/void/ccache/ccache.conf secondary config (readonly) /etc/ccache.conf stats updated Thu Nov 19 22:29:31 2020 cache hit (direct) 819345 cache hit (preprocessed) 178710 cache miss 11381469 cache hit rate 8.06 % called for link 994196 called for preprocessing 994011 multiple source files 1762 compiler produced stdout 9438 compiler produced no output 77 compiler produced empty output 10314 compile failed 200101 ccache internal error 613 preprocessor error 145901 can't use precompiled header 89380 bad compiler arguments 162657 unsupported source language 62376 autoconf compile/link 867964 unsupported compiler option 93317 unsupported code directive 1051 output to stdout 4 could not write to output file 6 no input file 345577 cleanups performed 2489 files in cache 8008769 cache size 654.3 GB max cache size 768.0 GB ```