svn commit: r263778 - in head: bin lib lib/clang sbin share/mk usr.bin usr.sbin

[Warner Losh]

(sorry for the top post)

This looks good to my eye. I’d be tempted to toss in a comment about the
__wait=.WAIT construct is due to the primitive nature of bmake’s parser
so it runs afoul of the .for/.if construction rules and this is needed to expand
the for variable. It tripped me up when I looked at it, until I recalled a comment
from similar code in NetBSD.

Warner

On Apr 21, 2014, at 7:15 AM, Ian Lepore <ian at FreeBSD.org> wrote:

> On Thu, 2014-03-27 at 20:44 +0100, Dimitry Andric wrote:
>> On 27 Mar 2014, at 19:12, Jilles Tjoelker <jilles at stack.nl> wrote:
>>> On Thu, Mar 27, 2014 at 11:05:00AM -0600, Warner Losh wrote:
>>>> On Mar 26, 2014, at 4:30 PM, Dimitry Andric <dim at freebsd.org> wrote:
>>>>> Author: dim
>>>>> Date: Wed Mar 26 22:30:38 2014
>>>>> New Revision: 263778
>>>>> URL: http://svnweb.freebsd.org/changeset/base/263778
>>> 
>>>>> Log:
>>>>> Add a SUBDIR_PARALLEL option to bsd.subdir.mk, to allow make to process
>>>>> all the SUBDIR entries in parallel, instead of serially.  Apply this
>>>>> option to a selected number of Makefiles, which can greatly speed up the
>>>>> build on multi-core machines, when using make -j.
>>> 
>>>>> This can be extended to more Makefiles later on, whenever they are
>>>>> verified to work correctly with parallel building.
>>> 
>>>> Why not have this ‘opt out’ rather than ‘opt in’ like it is now? Are
>>>> there any known bad dependencies this introduces?
>>> 
>>> I'm paranoid about build systems ;) It is easy to add dependencies
>>> across directories and as long as directories are built in sequence,
>>> nothing goes wrong.
>>> 
>>> In fact, I had enabled SUBDIR_PARALLEL in sys/modules/Makefile as well,
>>> but this caused mysterious failures with some kernels such as mips
>>> ADM5120.
>> 
>> There are a bunch of other parts that don't really like parallel builds
>> at the moment.  For example, gnu/usr.bin/binutils needs its libraries
>> (libbfd.a, etc) built first, before it can link the programs.  Similar
>> for gnu/usr.bin/cc, which needs libiberty, libcpp, etc before being able
>> to build the rest of gcc.
>> 
>> Most of these cases can hopefully be solved by adding .WAIT targets at
>> strategic points in the SUBDIR lists, but this also needs a bit of extra
>> logic in bsd.subdir.mk.
>> 
>> -Dimitry
>> 
> 
> It turns out I needed the .WAIT functionality to use SUBDIR_PARALLEL for
> $work, so I came up with the attached, does this look okay to commit?
> 
> -- Ian
> 
> diff -r 67802e319fc6 share/mk/bsd.subdir.mk
> --- a/share/mk/bsd.subdir.mk	Sun Apr 20 21:01:07 2014 -0600
> +++ b/share/mk/bsd.subdir.mk	Mon Apr 21 06:59:37 2014 -0600
> @@ -4,10 +4,10 @@
> # The include file <bsd.subdir.mk> contains the default targets
> # for building subdirectories.
> #
> -# For all of the directories listed in the variable SUBDIRS, the
> +# For all of the directories listed in the variable SUBDIR, the
> # specified directory will be visited and the target made. There is
> # also a default target which allows the command "make subdir" where
> -# subdir is any directory listed in the variable SUBDIRS.
> +# subdir is any directory listed in the variable SUBDIR.
> #
> #
> # +++ variables +++
> @@ -42,7 +42,7 @@ distribute:
> 
> _SUBDIR: .USE
> .if defined(SUBDIR) && !empty(SUBDIR) && !defined(NO_SUBDIR)
> -	@${_+_}for entry in ${SUBDIR}; do \
> +	@${_+_}for entry in ${SUBDIR:N.WAIT}; do \
> 		if test -d ${.CURDIR}/$${entry}.${MACHINE_ARCH}; then \
> 			${ECHODIR} "===> ${DIRPRFX}$${entry}.${MACHINE_ARCH} (${.TARGET:realinstall=install})"; \
> 			edir=$${entry}.${MACHINE_ARCH}; \
> @@ -57,7 +57,7 @@ distribute:
> 	done
> .endif
> 
> -${SUBDIR}: .PHONY
> +${SUBDIR:N.WAIT}: .PHONY
> 	${_+_}@if test -d ${.TARGET}.${MACHINE_ARCH}; then \
> 		cd ${.CURDIR}/${.TARGET}.${MACHINE_ARCH}; \
> 	else \
> @@ -65,13 +65,18 @@ distribute:
> 	fi; \
> 	${MAKE} all
> 
> +__wait=.WAIT
> .for __target in all all-man checkdpadd clean cleandepend cleandir \
>     depend distribute lint maninstall manlint \
>     obj objlink realinstall regress tags \
>     ${SUBDIR_TARGETS}
> .ifdef SUBDIR_PARALLEL
> +__subdir_targets=
> .for __dir in ${SUBDIR}
> -${__target}: ${__target}_subdir_${__dir}
> +.if ${__wait} == ${__dir}
> +__subdir_targets+= .WAIT
> +.else
> +__subdir_targets+= ${__target}_subdir_${__dir}
> ${__target}_subdir_${__dir}: .MAKE
> 	@${_+_}set -e; \
> 		if test -d ${.CURDIR}/${__dir}.${MACHINE_ARCH}; then \
> @@ -85,7 +90,9 @@ distribute:
> 		fi; \
> 		${MAKE} ${__target:realinstall=install} \
> 		    DIRPRFX=${DIRPRFX}$$edir/
> +.endif
> .endfor
> +${__target}: ${__subdir_targets}
> .else
> ${__target}: _SUBDIR
> .endif