[llvm-dev] Building with LLVM_PARALLEL_XXX_JOBS

Tue Mar 1 13:12:01 PST 2016

For faster builds and rebuilds you should definitely read:
https://blogs.s-osg.org/an-introduction-to-accelerating-your-build-with-clang/
https://blogs.s-osg.org/a-conclusion-to-accelerating-your-build-with-clang/

Hope this helps!

On Tue, Mar 1, 2016 at 9:17 PM, ChrisBieneman via llvm-dev <
llvm-dev at lists.llvm.org> wrote:

>
>
> > On Mar 1, 2016, at 10:01 AM, Mehdi Amini <mehdi.amini at apple.com> wrote:
> >
> >
> >> On Mar 1, 2016, at 9:57 AM, Chris Bieneman <cbieneman at apple.com> wrote:
> >>
> >> There are a few notes I'd like to add to this thread.
> >>
> >> (1) we have a number of places throughout out CMake build where we use
> features from newer CMakes gated by version checks. Most of these features
> are performance or usability related. None of them are correctness. Using
> the latest CMake release will often result in faster builds, so I encourage
> it.
> >>
> >> (2) CMake's "install" target will pretty much always be slower from
> clean than the old autoconf/make "install" target. This is because in CMake
> "install" depends on "all", and our CMake builds more stuff in "all" than
> autoconf did. To help with this or CMake system has lots of convenient
> "install-${name}" targets that support component-based installation. Not
> every component has one of these rules, but if one you need is missing let
> me know. I also recently (r261681) added a new option
> (LLVM_DISTRIBUTION_COMPONENTS) that allows you to specify a list of
> components that have custom install targets. It then creates a new
> "install-distribution" target that wraps just the components you want. For
> Apple this is almost a 40% speed up over "ninja install".
> >
> > That sounds great, I want to use it!
> > It would even be more awesome with an description/example in
> docs/CMake.rst :)
>
> Once I get the last of the kinks worked out for our internal adoption I'm
> going to open source our config files that use it.
>
> I've also made a note to remind myself to document it in docs/CMake.rst. I
> need to do a pass updating that with a bunch of the cool new things we're
> doing with CMake. Thanks for the reminder.
>
> -Chris
>
> >
> > --
> > Mehdi
> >>
> >> On Feb 25, 2016, at 11:08 AM, Sedat Dilek via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
> >>
> >>>> Which combination of cmake/ninja versions are you using (latest are
> >>>> v3.4.3 and v1.6.0)?
> >>>
> >>> With this combination I could reduce build-time down from approx. 3h
> >>> down to 01h20m.
> >>>
> >>> $ egrep -i 'jobs|ninja' llvm-build/CMakeCache.txt
> >>> //Program used to build from build.ninja files.
> >>> CMAKE_MAKE_PROGRAM:FILEPATH=/opt/cmake/bin/ninja
> >>> //Define the maximum number of concurrent compilation jobs.
> >>> LLVM_PARALLEL_COMPILE_JOBS:STRING=3
> >>> //Define the maximum number of concurrent link jobs.
> >>> LLVM_PARALLEL_LINK_JOBS:STRING=1
> >>> CMAKE_GENERATOR:INTERNAL=Ninja
> >>>
> >>> $ LC_ALL=C ls -alt
> logs/3.8.0rc3_clang-3-8-0-rc3_cmake-3-4-3_ninja-1-6-0/
> >>> total 360
> >>> drwxr-xr-x 2 wearefam wearefam   4096 Feb 25 19:58 .
> >>> drwxr-xr-x 6 wearefam wearefam   4096 Feb 25 19:58 ..
> >>> -rw-r--r-- 1 wearefam wearefam 130196 Feb 25 19:54
> >>> install-log_llvm-toolchain-3.8.0rc3.txt
> >>> -rw-r--r-- 1 wearefam wearefam 205762 Feb 25 19:51
> >>> build-log_llvm-toolchain-3.8.0rc3.txt
> >>> -rw-r--r-- 1 wearefam wearefam  14331 Feb 25 18:30
> >>> configure-log_llvm-toolchain-3.8.0rc3.txt
> >>>
> >>> $ LC_ALL=C du -s -m llvm* /opt/llvm-toolchain-3.8.0rc3
> >>> 315     llvm
> >>> 941     llvm-build
> >>> 609     /opt/llvm-toolchain-3.8.0rc3
> >>>
> >>> - Sedat -
> >>>
> >>> [1] https://cmake.org/files/v3.5/cmake-3.5.0-rc3-Linux-x86_64.tar.gz
> >>> _______________________________________________
> >>> LLVM Developers mailing list
> >>> llvm-dev at lists.llvm.org
> >>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
> >
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