Hi, Otto! On Dec 28, Otto Kekäläinen wrote:
The time saving is huge. My full git-buildpackage run went down from 25-33 minutes to about 4 minutes.
...
By the way, why does not the buildbot infrastructure use ccache? It could have a common nfs mounted /var/ccache directory that all the builds share that could presists from build-to-build? Most of the commits just touch a few files so ccache would be able to save lots of compilation time as only the changed files would be compiled.
Because nobody implemented that. And, I suspect, that's because compiling is the fastest step in buildbot already. Downloading the sources (from buildmaster to buildslaves) and uploading packages (back to buildmaster) used to be the slowest step (1-2 hours was not uncommon, 3 hours was possible). Testing usually takes about half an hour. Compiling with its mere 15 minutes is simply not worth optimizing. I've recently fixed the downloading step - it wasn't network at all, something was wrong on twisted or buildbot level. Now I need to fix uploading. Then testing will be next in line - we already have a solution for that, GSoC project of this year, implemented by Pablo Estrada with Elena being the mentor. And only when testing will be taking ~5 minutes (ok, below 10), then one can start thinking about optimizing the build. Otherwise that won't make any noticeable difference to the buildbot throughput. Regards, Sergei