[llvm-dev] Disk space and RAM requirements in docs

Petr Penzin via llvm-dev llvm-dev at lists.llvm.org
Fri May 3 19:59:12 PDT 2019

Thank you for all the replies.

I deleted the build directory and re-ran CMake from scratch, still got 
to 70 GB on FreeBSD. My Linux debug build is around 40 GB, which is what 
is everyone seem to expect, so I have two questions:

- Would it be reasonable to update the Getting Started document to bump 
up the size of statically linked debug build to 30-40 GB?

- I am also very curious about the size disparity between the build on 
my machine and David's, any pointers would be greatly appreciated.

On 4/30/19 6:23 AM, David Chisnall wrote:
> On 30/04/2019 04:29, Petr Penzin via llvm-dev wrote:
>> Hi,
>> Have anybody recently built LLVM in Debug mode /within/ space 
>> requirements from the Getting Started doc?
>> https://llvm.org/docs/GettingStarted.html#hardware
>>  > An LLVM-only build will need about 1-3 GB of space. A full build 
>> of LLVM and Clang will need around 15-20 GB of disk space.
>>  From my experience this numbers looks drastically low. On FreeBSD my 
>> recent builds consumed more than 70 GB and on Linux - more than 60. I 
>> am building LLVM, Clang, and LLD with all default targets and default 
>> settings. On FreeBSD I am also building Polly. Also, building 
>> `clang-check` target adds around to 20 GB to the build directory size.
> It looks as if running the tests is adding a lot of space to your 
> builds.  I have three LLVM trunk build directories on this machine 
> (FreeBSD):
> Release, building clang, clang-tools-extras, and lld: 1.2GB
> Debug, building clang, clang-tools-extras, and lld: 36GB
> Debug + ASan, building clang, lldb, and lld: 40GB

Can you please share your build settings for debug builds (any extra 
CMake variables that you set)? Are you using the system toolchain? I'll 
try to compare build output structure to the structure of Linux build 
next week, may be there are some clues.



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