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Re: WPA stream_out form & memory consumption


> Hello,
>    I've been compiling Chromium with LTO and I noticed that WPA
> stream_out forks and do parallel:
> http://gcc.gnu.org/ml/gcc-patches/2013-11/msg02621.html.
> 
> I am unable to fit in 16GB memory: ld uses about 8GB and lto1 about
> 6GB. When WPA start to fork, memory consumption increases so that
> lto1 is killed. I would appreciate an --param option to disable this
> WPA fork. The number of forks is taken from build system (-flto=9)
> which is fine for ltrans phase, because LD releases aforementioned
> 8GB.
> 
> What do you think about that?

I can take a look - our measurements suggested that the WPA memory will
be later dominated by ltrans.  Perhaps Chromium does something that makes
WPA to explode that would be interesting to analyze.  I did not managed
to get through Chromium LTO build process recently (ninja builds are not
my friends), can you send me the instructions?

Honza
> 
> Thanks,
> Martin


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