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Date:   Sat, 29 Jul 2023 10:31:28 +0200
From:   Willy Tarreau <w@1wt.eu>
To:     Thomas =?iso-8859-1?Q?Wei=DFschuh?= <thomas@t-8ch.de>
Cc:     Zhangjin Wu <falcon@tinylab.org>, arnd@arndb.de,
        linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org
Subject: Re: [PATCH v3 12/12] selftests/nolibc: speed up some targets with
 multiple jobs
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On Sat, Jul 29, 2023 at 08:44:32AM +0200, Thomas Weißschuh wrote:
> On 2023-07-28 04:35:01+0800, Zhangjin Wu wrote:
> > The sysroot install and kernel build targets are time cost, let's use
> > -j<N> to parallelize them with multiple jobs.
> > 
> > Signed-off-by: Zhangjin Wu <falcon@tinylab.org>
> > ---
> >  tools/testing/selftests/nolibc/Makefile | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/tools/testing/selftests/nolibc/Makefile b/tools/testing/selftests/nolibc/Makefile
> > index ad2538ec5eb0..1b45c22f9a94 100644
> > --- a/tools/testing/selftests/nolibc/Makefile
> > +++ b/tools/testing/selftests/nolibc/Makefile
> > @@ -171,7 +171,7 @@ PHONY = sysroot/$(ARCH)/include
> >  sysroot/$(ARCH)/include:
> >  	$(Q)rm -rf sysroot/$(ARCH) sysroot/sysroot
> >  	$(QUIET_MKDIR)mkdir -p sysroot
> > -	$(Q)$(MAKE) -C ../../../include/nolibc ARCH=$(ARCH) OUTPUT=$(CURDIR)/sysroot/ headers_standalone
> > +	$(Q)$(MAKE) -j$$(nproc) -C ../../../include/nolibc ARCH=$(ARCH) OUTPUT=$(CURDIR)/sysroot/ headers_standalone
> 
> This should already work when the users specify -j on the make command
> line themselves.
> I'm not a fan of force-enabling it here.

Indeed, we must not do that, because some users might for instance
prefer to build multiple archs in parallel and benefit from a better
parallelism and now they'd end up with too many processes.

Willy