[llvm-dev] Building with LLVM_PARALLEL_XXX_JOBS

Wed Mar 2 16:22:51 PST 2016

I got some more inspirations on how to speedup my build and integrated
the URLs into my scripts (attached).

For example to use GOLD as linker or to use '-O3' OptLevel maybe in
combination with LTO and PGO (using '-O3 -flto -fprofile-use').

Let's see when the v3.8.0 FINAL is released.

- Sedat -

On 3/2/16, Fabio Pagani <pagabuc at gmail.com> wrote:
> Hey Chris,
>
> Sedat was asking for a way to "to speedup my build" and those blog posts
> were really helpful to me.
> Anyway LLVM_DISTRIBUTION_COMPONENTS sounds very cool, hope you will push
> your code soon!
>
> On Tue, Mar 1, 2016 at 11:32 PM, Chris Bieneman <cbieneman at apple.com>
> wrote:
>
>> Fabio, the work I was mentioning here is an extension beyond those blog
>> posts.
>>
>> Some details:
>>
>> * The “almost 40%” number I referred to is a multi-stage clang build.
>> That
>> means we build a host-capable compiler, then build the actual compiler we
>> want to ship.
>> * I’m at Apple, so points 1 and 2 are already covered (we only use clang,
>> and ld64 is a fast linker).
>> * Our system compiler is PGO+LTO’d, but our stage1 isn’t. Stage1 isn’t
>> because the performance improvement of PGO+LTO is less than the time it
>> takes to build, and stage1 is basically a throwaway.
>> * We are using Ninja and CMake, but this configuration isn’t really
>> significantly faster than autoconf/make, and actually “ninja install” is
>> slower in my tests than the old autoconf “make install”. The slowdown is
>> almost entirely due to Ninja’s “all” target being a lot bigger.
>> * This performance is for clean builds, not incremental so ccache or
>> shared libraries would not be a valid optimization
>> * We do use optimized tablegen
>> * “Build Less” is exactly what the LLVM_DISTRIBUTION_COMPONENTS enables,
>> just in a friendly wrapper target.
>>
>> -Chris
>>
>>
>>
>> On Mar 1, 2016, at 1:12 PM, Fabio Pagani <pagabuc at gmail.com> wrote:
>>
>> 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
>>> >
>>> _______________________________________________
>>> LLVM Developers mailing list
>>> llvm-dev at lists.llvm.org
>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>>
>>
>>
>>
>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: build_llvm-toolchain_clang-cmake-ninja.sh
Type: application/x-sh
Size: 3728 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20160303/fa3f74c0/attachment.sh>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: install_llvm-toolchain_clang-cmake-ninja.sh
Type: application/x-sh
Size: 3223 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20160303/fa3f74c0/attachment-0001.sh>