On Tue, Jul 28, 2020 at 15:08:11 +0100, Daniel Berrange wrote:
> On Tue, Jul 28, 2020 at 04:04:39PM +0200, Pavel Hrdina wrote:
> > On Tue, Jul 28, 2020 at 03:48:29PM +0200, Peter Krempa wrote:
> > > On Thu, Jul 16, 2020 at 11:59:38 +0200, Pavel Hrdina wrote:
> > > > Signed-off-by: Pavel Hrdina <phrdina@xxxxxxxxxx>
> > > > ---
> > > > build-aux/Makefile.in | 9 +++
> > > > .../Makefile.nonreentrant | 0
> > > > build-aux/meson.build | 30 +++++++++
> > > > build-aux/syntax-check.mk | 62 +++++++++----------
> > > > meson.build | 2 +
> > > > 5 files changed, 72 insertions(+), 31 deletions(-)
> > > > create mode 100644 build-aux/Makefile.in
> > > > rename Makefile.nonreentrant => build-aux/Makefile.nonreentrant (100%)
> > > > create mode 100644 build-aux/meson.build
> > >
> > > [...]
> > >
> > > > +make_prog = find_program('make')
> > > > +
> > > > +# There is no way how to pass value to -j using run_target so let's use
> > > > +# it without any value to run all tests in parallel.
> > > > +run_target(
> > > > + 'syntax-check',
> > > > + command: [
> > > > + make_prog, '-C', meson.current_build_dir(), '-j', 'syntax-check',
> > > > + ],
> > >
> > > While I do run syntax check with unlimited '-j'. I don't think it's
> > > entirely cool to impose that on everybody. Specifically overcommiting
> > > the system is not cool. Since meson is automagically scaling can't we
> > > use the meson-detected cpu number here?
> >
> > Unfortunately no, that was the first thing I was trying to figure out
> > by going through meson code as well. It's not ideal I know.
> >
> > Other options are to not use -j at all which is no-go or we can add some
> > code to detect the available number of CPUs. But again it would not
> > reflect the fact if user runs 'ninja -j N'.
>
> In libosinfo we put "syntax-check" as part of the unit tests, rather
> than as a separate meson target. With that you don't need to pass
> -j to syntax-check, because other unit tests are running in parallel
> already, and chances are syntax-check will finish first even when
> serialized.
Unfortunately it's not even close.
Serialized syntax-check:
real 0m22.139s
user 0m24.209s
sys 0m6.788s
test suite:
real 0m4.833s
user 0m12.408s
sys 0m3.918s
syntax-check with -j == ncpus: (24 thread box)
real 0m2.099s
user 0m28.558s
sys 0m7.739s
As said, I'm a big fan of -jncpus or -j. so I really want to keep it
especially given the data above, but on the other hand I don't want to
set the CI boxes on fire.
