[LLVMdev] RFC: Upcoming Build System Changes
ofv at wanadoo.es
Tue Nov 1 16:33:01 PDT 2011
greened at obbligato.org (David A. Greene) writes:
> Joachim Durchholz <jo at durchholz.org> writes:
>> On the reasons why make-based builds are slow, Peter Miller has some
>> insight to offer:
>> http://miller.emu.id.au/pmiller/books/rmch/ .
>> I'm not sure how widely recognized that paper is. Maybe it's widely
>> known and today's build times stem from other things than recursive make.
> The paper is widely recognized. Its lessons, unfortunatly, are not.
> Chris is absolutely on-target as to why the current build is slow. It's
> slow because recursive make hides the parallelism. It hides the
> parallelism because it hides the dependencies. There is no way to get
> around that problem with a recursive make build system.
You keep repeating that and I say that it is wrong. Can you mention a
serialization point on the LLVM build caused by recursive make?
(GenLibDeps is not such example, as described on a previous message.)
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