On 28-6-2018 16:03, Erwan Velu wrote: > Hi Folks, > > I've been wondering why the ccache was that inefficient on the CI. > It appear and that is confirmed by local builds that two consecutives builds of the exact same code leads to < 1% of cache hit. > This is actually a very bad cache performance : As the cache hit is very low, the needed time to create the cache is not compensated, leading to a 10% loss of performance regarding a build without ccache. These are my current ccache stats, and they are of different filesets: % ccache -s cache directory /home/wjw/.ccache primary config /home/wjw/.ccache/ccache.conf secondary config (readonly) /usr/local/etc/ccache.conf cache hit (direct) 4002 cache hit (preprocessed) 740 cache miss 14242 cache hit rate 24.98 % called for link 4312 compile failed 85 preprocessor error 27 unsupported source language 1167 cleanups performed 775 files in cache 1238 cache size 4.4 GB max cache size 5.0 GB Also note that changing one of the more used header files, sort of renders you cache useless, because then everything needs to be recompiled. --WjW -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
