[llvm-dev] LLVM building problem

[Dimitry Andric via llvm-dev]

On 19 Sep 2019, at 11:24, Enrique González via llvm-dev <llvm-dev at lists.llvm.org> wrote:
> 
> I'm using a Virtual Machine with Ubuntu 18.04 at VIrtualBox and I'm trying to build the LLVM project from https://github.com/llvm/llvm-project.git.
> 
> This VM has 6 cores (from an intel core i-7 8th gen), 11GB of RAM and 300GB of storage (from a 1TB HDD) at a laptop, this is the model: MSI GS63 Stealth 8RE.
> 
> Then, I'm doing exactly that this tutorial says to build LLVM: https://llvm.org/docs/GettingStarted.html
> 
> 1) Clone the project from git: "git clone  https://github.com/llvm/llvm-project.git".
> 2) Use cmake at the build directory: "cmake -G 'Ninja' ../llvm".
> 3) Build the project with ninja: "ninja" (i do not use any flag).
> 
> It seems to build well until i reach the final part, where the build try to link CXX executables. At this point, the VM freeze and I cannot do anything. I also have tried to expand the SWAP memory creating a second swap file with 90GB and the VM also freeze.

Try adding -D LLVM_PARALLEL_LINK_JOBS=1 to your CMake command line.  The problem is that ninja will likely start 12 (on your system at least) link jobs at the same time, since these tend to bunch together.  That will rapidly exhaust almost any machine's memory.

If -D LLVM_PARALLEL_LINK_JOBS=1 works, you can try increasing it bit by bit until the memory usage is acceptable.

And yes, this setting should most likely be a default... :)

-Dimitry

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