We have a large cross-compilation environment that is essentially identical on both Linux and MacOS X hosts. The build system uses ccache to try to reduce redundant recompilation, but we're seeing radically different outcomes on OSX versus Linux hosts. We're still using ccache 2.4.
On Linux hosts, the aggregate performance seems to be roughly a 3:1 cache hit-to-miss ratio. However, on OSX, ccache seems to be providing almost no benefit: we see something like a 1:15 cache hit-to-miss ratio -- at which point we might as well not be using ccache at all. I've been looking into this a bit with 3.0 (actually tip of tree) on OSX. Using ccache 3 [in its default mode of direct mode then fallback to preprocessor], 90%+ of the misses that I see in the log are failure to find the manifest file at all, and I'm seeing a similar very low hit rate overall. Right now I'm doing some tests around using the new CCACHE_SLOPPINESS=file_macro tweak, and initial results are promising... but that begs the question of why the results on OSX with 2.4 are so poor in general. The obvious guess is that there's *something* about our cross-build chain and environment that differs from the Linux-hosted versions just enough to be upsetting ccache. Any tips on what I should go looking for? Thanks! -- chris tate android framework engineer _______________________________________________ ccache mailing list email@example.com https://lists.samba.org/mailman/listinfo/ccache