It uses a single generated Makefile, that is not the problem. The slow
code is extracting the dependencies.
Unlike the broken make dep, kbuild 2.5 extracts accurate dependencies
by using the -MD option of cpp and post processing the cpp list. The
post processing code is slow because the current design requires every
compile to read a complete list of all the files, giving O(n^2)
effects. Mark 2 of the core code will use a shared database with
concurrent update so post processing is limited to looking up just the
required files, instead of reading the complete list every time.
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to email@example.com
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/