[llvm-dev] (Thin)LTO llvm build

Carsten Mattner via llvm-dev llvm-dev at lists.llvm.org
Fri Sep 16 18:13:52 PDT 2016

On Sat, Sep 17, 2016 at 2:07 AM, Teresa Johnson via llvm-dev
<llvm-dev at lists.llvm.org> wrote:

> Yes and to add on - the ThinLTO backend by default will
> kick off  std::thread::hardware_concurrency # of threads, which I'm finding is

Is it just me or does that sound not very intuitive or at least a
little unexpected?
It's good that it uses the resources eagerly, but in terms of build systems this
is certainly surprising if there's no control of that parameter via

> too much for machines with hyperthreading. If that ends up being an issue I can
> give you a workaround (I've been struggling to find a way that works on various
> OS and arches to compute the max number of physical cores to fix this in the source).

I've been using ninja -jN so far. I suppose when building with ThinLTO I should
run ninja -j1. Would that

What's the workaround?

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