Re: RFC: less chatty system builds

On Thu, Dec 19, 2013 at 1:18 AM, David Chisnall <theraven_at_freebsd.org>wrote:

> On 16 Dec 2013, at 21:35, Dimitry Andric <dim_at_FreeBSD.org> wrote:
>
> > In any case, if anything like this is implemented, I would really prefer
> > something like CMake does, e.g. give you a percentage counter that
> > provides some information about how 'far' the build is progressing.
>
> I haven't seen this for a while, because I now use ninja exclusively for
> building any projects that use CMake.  The output of Ninja is pretty close
> to my ideal for a build system, and so I'd recommend that anyone hacking on
> this look at it.  It looks something like this while building:
>
> $ ninja
> [1/22] Building CXX object
> lib/Target/Mips/AsmParser/CMakeFiles/LLVMMipsAsmParser.dir/MipsAsmParser.cpp.o
>
> The [1/22] part is a counter of the number of build steps done and updates
> in place.  The 'Building CXX object ...' part tells you what the current
> rule is and what it's being applied to.  This is only approximate, as it
> usually does parallel builds, but it gives you some idea of what's
> happening.
>
>
the "Building CXX ... " is basically the same type of output that I was
proposing.
I am still unclear on how one can implement useful counters (see my other
email)
since the times of "build step" vary by 2-3 orders of magnitude.
Anyways, maybe just counting the number of targets in the first 2-3 levels
of
the tree can give an idea.

If a command produces warning output but exits with success, then that
> command's output is dumped to stdout (explicitly serialised by Ninja so
> that it's never interleaved with another command's output).
>
> If a command exits with a failure condition, then Ninja dumps the exact
> command line that was used, along with all of the output, and then stops.
>  Another side benefit is that Ninja always uses absolute paths for invoking
> the commands and for arguments, and so you can always just re-run that
> single failing command.
>
> Oh, and when I do a build of LLVM/Clang on my laptop using Ninja, it takes
> about 3-5 minutes, whereas when I do it with our build system it takes
> about 15.  When I do it on a 24-core server, it takes less than two minutes
> with Ninja and with ours it takes about 15 (no speedup over my laptop).
>  I'd therefore suggest that there might be more pressing things that need
> fixing with our antiquated build infrastructure than the prettiness of the
> output...
>

these are orthogonal issues though, and so radically different in
complexity that it does not seem a waste of energy to apply
the patch i suggested while someone comes up with an improved build
system.

cheers
luigi