On Fri, Oct 26, 2018 at 7:57 AM Stefan Seefeld via Boost-build <boost-build@lists.boost.org> wrote:

On 2018-10-25 10:46 p.m., Rene Rivera via Boost-build wrote:

While adding the "--debug" option for building I added LTO to the release build. And that gives an overall 11% perf improvement (with xcode 10 clang).

That's quite impressive. I'd be curious to see a heat map showing where the time is spent. I was expecting most of the time being spent in running subprocesses (the actual commands), rather than within b2 itself. So an overall performance improvement of 11% based on work on b2 itself suggests that assumption is wrong.

I should have mentioned that I don't measure with build times. The improvements are *only* the b2 parsing and make generation. What I do is run a fake build on the Boost tree like this:

time ../../bfgroup/b2-c --build-type=complete -n -d0 --layout=versioned

I run it multiple times so it's mostly hot code already. And the config checks are all cached.