Date: Thu, 13 Feb 2014 14:14:01 -0500 From: Glen Barber <gjb@FreeBSD.org> To: Marcel Moolenaar <marcel@xcllnt.net> Cc: freebsd-toolchain@FreeBSD.org Subject: Re: bmake(1) "sometimes" honors '-j' ? Message-ID: <20140213191401.GJ1667@glenbarber.us> In-Reply-To: <2510126A-ECD7-4DC7-A936-23824B233821@xcllnt.net> References: <20140209213618.GA63417@glenbarber.us> <2510126A-ECD7-4DC7-A936-23824B233821@xcllnt.net>
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On Thu, Feb 13, 2014 at 09:23:19AM -0800, Marcel Moolenaar wrote:
>=20
> On Feb 9, 2014, at 1:36 PM, Glen Barber <gjb@FreeBSD.org> wrote:
>=20
> > Maybe there is an obvious answer to this, or maybe I just do not
> > understand how computers work.
> >=20
> > For snapshot builds for RPI-B and BEAGLEBONE, I am hard-coding '-j10'
> > for buildworld and '-j6' for buildkernel, because these values are
> > somewhat "safe" considering various race conditions with high '-j'
> > values. Crochet sets the '-j' value to '1', if WORLDJOBS and
> > KERNJOBS are not set, so what I end up with is basically:
> > 'make [...] -j10 -j1 ${.TARGET}'.
> >=20
> > What I see in ps(1) is a bit confusing to me, though.
> >=20
> > For example, the following suggests '-j10' is being honored for the
> > 'libraries' target, but '-j1' is being forced for the 'buildworld'
> > target, and I'm not sure I understand why. (Lines broken up for
> > readability.)
> >=20
> > root@grind:~ # ps auxww | grep make | grep 'j'
> >=20
> > root 67766 0.0 0.0 9024 1048 4 S+ 7:20PM 0:03.02 make
> > TARGET_ARCH=3Darmv6 SRCCONF=3D/dev/null __MAKE_CONF=3D/dev/null -j10 -=
j 1 buildworld
> >=20
> > root 13112 0.0 0.0 9024 1488 4 S 8:24PM 0:00.94 make
> > -j10 -f Makefile.inc1 DESTDIR=3D/usr/obj/arm.armv6/usr/src/tmp -DNO_FS=
CHG
> > -DWITHOUT_HTML -DWITHOUT_INFO -DNO_LINT -DWITHOUT_MAN -DNO_PROFILE
> > -DNO_TESTS libraries
> >=20
> > So, if I am reading this correctly, the 'libraries' target is honoring
> > the '-j10', and 'buildworld' is honoring the later-specified '-j1'.
> >=20
> > Am I reading this incorrectly, or is this something I just do not
> > understand about our toolchain?
>=20
> I can't give an authoritative answer, but there are a few
> things to consider:
>=20
> 1. MAKEFLAGS is set by make(1) for later use. There's also the
> .MAKEFLAGS variant. I don't know the *exact* difference
> between them, but our makefile, including Makefile.inc1, uses
> the variable and passes it to sub-makes.
> 2. make/bmake itself sets MAKEFLAGS/.MAKEFLAGS and automatically
> passes it to sub-makes. So when a makefile sets it, it's to
> override the default.
> 3. The .MAKEFLAGS variable holds the exact set of options passed
> to make. For example:
> % make -j10 -j1 -V .MAKEFLAGS
> -j 10 -j 1 -V .MAKEFLAGS
>=20
> What this means is that -j10 gets passed around and as such
> can be used, not withstanding the fact that -j1 follows and
> make itself may use that instead. Point 1 above applies.
>=20
> For best results, pass only 1 -j flag or alternatively we need
> to fix our makefiles to only keep the last -j in MAKEFLAGS, etc.
>=20
In this specific scenario, it was not intentional. I had left out
a configuration entry, and the intended '-j10' was being overridden.
Anyway, thank you for the explanation. It does make sense.
Glen
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