Re: OOM while building ghc 9.4.5

On Sat, Jul 29, 2023 at 2:44 AM Ilias Tsitsimpis <[email protected]> wrote:
>
> On Fri, Jul 28, 2023 at 05:09PM, Jeffrey Walton wrote:
> > Break that source file up into two or three more manageable pieces.
> >
> > If I am parsing the command line correctly, the source file is
> > Instances.hs and the output file is Instances.p_o. I would try to
> > create Instances_1.hs, Instances_2.hs and Instances_3.hs, and then let
> > the linker combine their object files later.
> >
> > What I don't know is, is it possible to do that in Haskell. Some
> > languages are picky about things like that. C# and Java come to mind.
>
> This was suggested as a solution by upstream as well (see [1]) but they
> found it was too difficult to do and ended up using to -O0 instead.
>
> [1] https://gitlab.haskell.org/ghc/ghc/-/issues/18256

The 18256 issue looks like it is a different complaint. 18256 tries to
speed up compile time. An OOM kill is a different problem.

Looking at the original command, the project is using -O, which is
-O2. Maybe you can drop it to -O1 -fno-inline.

>From Crypto++, I've found there's no material difference between -O1,
-O2 or -O3. Crypto++ provides SSE/AVX/NEON/ASIMD/Altivec acceleration
where it matters, so compiler optimizations make almost no difference
at runtime according to benchmarks.

I see Debian has https://wiki.debian.org/ReduceBuildMemoryOverhead,
but it does not look too helpful. (I updated with your discussion).