Re: [PATCH] meson: Pass -j option to sphinx

[Daniel P . Berrangé]

On Thu, Apr 27, 2023 at 02:24:59PM +0200, Thomas Huth wrote:
> On 26/04/2023 18.03, Fabiano Rosas wrote:
> > Save a bit of build time by passing the number of jobs option to
> > sphinx.
> > 
> > To avoid warnings from sphinx, alter our plugins to inform whether
> > they support parallelism. The two plugins touched are quite simple and
> > I don't see anything that would indicate they do not support being
> > called in parallel, so return True for both reads and writes.
> > 
> > before:
> >   $ time make -j16 man html
> >   ...
> >   [1/2] Generating docs/QEMU manual with a custom command
> >   [2/2] Generating docs/QEMU man pages with a custom command
> > 
> >   real    0m49.770s
> >   user    0m49.425s
> >   sys     0m0.716s
> > 
> > after:
> >   $ time make -j16 man html
> >   ...
> >   [1/2] Generating docs/QEMU manual with a custom command (wrapped by meson 
> > because command contains newlines)
> >   [2/2] Generating docs/QEMU man pages with a custom command (wrapped by 
> > meson because command contains newlines)
> >   real    0m30.153s
> >   user    1m5.945s
> >   sys     0m2.440s
> > 
> > Signed-off-by: Fabiano Rosas <farosas@suse.de>
> > ---
> >   docs/meson.build           | 12 ++++++++++++
> >   docs/sphinx/fakedbusdoc.py |  5 +++++
> >   docs/sphinx/qmp_lexer.py   |  5 +++++
> >   3 files changed, 22 insertions(+)
> > 
> > diff --git a/docs/meson.build b/docs/meson.build
> > index f220800e3e..9e4bed6fa0 100644
> > --- a/docs/meson.build
> > +++ b/docs/meson.build
> > @@ -10,6 +10,18 @@ if sphinx_build.found()
> >       SPHINX_ARGS += [ '-W', '-Dkerneldoc_werror=1' ]
> >     endif
> > +  sphinx_version = run_command(SPHINX_ARGS + ['--version'],
> > +                               check: false).stdout().split()[1]
> > +  if sphinx_version.version_compare('>=5.1.2')
> > +    SPHINX_ARGS += ['-j', 'auto']
> > +  else
> > +    nproc = find_program('nproc')
> > +    if nproc.found()
> > +      jobs = run_command(nproc, check:false).stdout()
> > +      SPHINX_ARGS += ['-j', jobs]
> > +    endif
> > +  endif
> 
> Wouldn't it be better to use the value from "make -jXX" instead of always
> running with the maximum number of processors here?

IIUC, this is not exposed by meson.

With regards,
Daniel
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