[Buildroot] [PATCH 1/2] jack2: use -j only when is PARALLEL_JOBS is defined

[Fabio Porcedda]

On Sun, Mar 29, 2015 at 3:17 PM, Thomas Petazzoni
<thomas.petazzoni at free-electrons.com> wrote:
> Dear Fabio Porcedda,
>
> On Sun, 29 Mar 2015 09:35:33 +0200, Fabio Porcedda wrote:
>> When top-level parallel makefile is being used the PARALLEL_JOBS is
>> empty but the build system of jack2 does not accept a -j without an
>> argument so don't use the -j option when PARALLEL_JOBS is empty.
>
> This is not quite true. PARALLEL_JOBS is empty because your
> recommendation of using:
>
>         make BR2_JLEVEL= -j$((`getconf _NPROCESSORS_ONLN`+1))
>
> for top-level parallel build is maybe not the most appropriate one.

Good idea!

> In addition, even when top-level parallel build is used, using purely
> sequential build in each package may not be the good solution. Imagine
> you have a number of packages to build, and one of them is particularly
> long: if you don't build this package in parallel, the build time may
> be increased.
>
> So I believe that with the introduction of top-level parallel build, we
> need a way of calculating a default reasonable BR2_JLEVEL, preferably
> taking into account the make -jX value passed to the top-level make. We
> indeed need to play on the number of jobs at the top-level, and the
> number of jobs at the per-package level.

About taking in account the value passed to -j i don't know an
automatic way to do it.

At least checking the MAKEFLAGS we can know if the -j options was used
so we can use something like this:

diff --git a/package/Makefile.in b/package/Makefile.in
index 803b162..698626f 100644
--- a/package/Makefile.in
+++ b/package/Makefile.in
@@ -18,7 +18,7 @@ PARALLEL_JOBS := $(BR2_JLEVEL)
 endif

 MAKE1 := $(HOSTMAKE) -j1
-MAKE := $(HOSTMAKE) $(if $(PARALLEL_JOBS),-j$(PARALLEL_JOBS))
+override MAKE = $(HOSTMAKE) $(if $(findstring j,$(filter-out
--%,$(MAKEFLAGS))),,-j$(PARALLEL_JOBS))

 ifeq ($(BR2_TOOLCHAIN_BUILDROOT),y)
 TARGET_VENDOR = $(call qstrip,$(BR2_TOOLCHAIN_BUILDROOT_VENDOR))

With this change we use can use the followin command line:
  make -jX

That way we  don't need to set as empty the BR2_JLEVEL  variable and
we can leave unchanged the lines that use the PARALLEL_JOBS variable.

> Also, your patch series does not handle all packages that use
> $(PARALLEL_JOBS) :
>
> package/boost/boost.mk: (cd $(@D) && ./b2 -j$(PARALLEL_JOBS) -q -d+1 \
> package/boost/boost.mk: (cd $(@D) && ./b2 -j$(PARALLEL_JOBS) -q -d+1 \
> package/boost/boost.mk: (cd $(@D) && ./b2 -j$(PARALLEL_JOBS) -q -d+1 \
> package/boost/boost.mk: (cd $(@D) && ./bjam -j$(PARALLEL_JOBS) -d+1 \
> package/cmake/cmake.mk:                 --parallel=$(PARALLEL_JOBS) -- \
> package/jack2/jack2.mk: (cd $(@D); $(HOST_DIR)/usr/bin/python2 ./waf build -j $(PARALLEL_JOBS))
> package/midori/midori.mk:       (cd $(@D); $(HOST_DIR)/usr/bin/python2 ./waf build -j $(PARALLEL_JOBS))
> package/qt/qt.mk:               MAKEFLAGS="$(MAKEFLAGS) -j$(PARALLEL_JOBS)" ./configure \
> package/qt5/qt5base/qt5base.mk:         MAKEFLAGS="$(MAKEFLAGS) -j$(PARALLEL_JOBS)" \
>
> We probably need to convert all of these to:
>
>         $(if $(PARALLEL_JOBS),-j$(PARALLEL_JOBS))
>
> like is done for the global $(MAKE) variable.

You are right.

Thanks for reviewing.
-- 
Fabio Porcedda