From 2cdfb9c04c5b37bee103eaf6b7e73f39f3b62b75 Mon Sep 17 00:00:00 2001
From: dim <dim@ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f>
Date: Wed, 9 Apr 2014 18:16:58 +0000
Subject: [PATCH] MFC r263778:

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.

I tested this on a 24-core machine, with make -j48 buildworld (N = 6):

		before    stddev       after    stddev
		=======   ======       =======  ======
real time        1741.1     16.5         959.8     2.7
user time       12468.7     16.4       14393.0    16.8
sys  time        1825.0     54.8        2110.6    22.8

(user+sys)/real     8.2                   17.1

E.g. the build was approximately 45% faster in real time.  On machines
with less cores, or with lower -j settings, the speedup will not be as
impressive.  But at least you can now almost max out a machine with
buildworld!

Submitted by:	jilles

MFC r263833:

Enable parallel building for gnu/usr.bin and usr.bin/clang too.


git-svn-id: svn://svn.freebsd.org/base/stable/8@264303 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
---
 bin/Makefile           |  2 ++
 gnu/usr.bin/Makefile   |  2 ++
 lib/Makefile           |  4 ++++
 sbin/Makefile          |  2 ++
 share/mk/bsd.subdir.mk | 19 +++++++++++++++++++
 usr.bin/Makefile       |  2 ++
 usr.sbin/Makefile      |  2 ++
 7 files changed, 33 insertions(+)

diff --git a/bin/Makefile b/bin/Makefile
index 3114e6700..765dd88e3 100644
--- a/bin/Makefile
+++ b/bin/Makefile
@@ -54,4 +54,6 @@ _rmail=	rmail
 _csh=	csh
 .endif
 
+SUBDIR_PARALLEL=
+
 .include <bsd.subdir.mk>
diff --git a/gnu/usr.bin/Makefile b/gnu/usr.bin/Makefile
index 9afd8ef14..cdf00a90e 100644
--- a/gnu/usr.bin/Makefile
+++ b/gnu/usr.bin/Makefile
@@ -63,4 +63,6 @@ _cc=		cc
 _gdb=		gdb
 .endif
 
+SUBDIR_PARALLEL=
+
 .include <bsd.subdir.mk>
diff --git a/lib/Makefile b/lib/Makefile
index 33ff1bcbb..0a2cce4f7 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -203,4 +203,8 @@ _libusbhid=	libusbhid
 _libusb=	libusb
 .endif
 
+.if !make(install)
+SUBDIR_PARALLEL=
+.endif
+
 .include <bsd.subdir.mk>
diff --git a/sbin/Makefile b/sbin/Makefile
index 72f4bff77..8cc016e12 100644
--- a/sbin/Makefile
+++ b/sbin/Makefile
@@ -154,4 +154,6 @@ _mca=		mca
 _sunlabel=	sunlabel
 .endif
 
+SUBDIR_PARALLEL=
+
 .include <bsd.subdir.mk>
diff --git a/share/mk/bsd.subdir.mk b/share/mk/bsd.subdir.mk
index b0d0a3c08..ea2b3b03f 100644
--- a/share/mk/bsd.subdir.mk
+++ b/share/mk/bsd.subdir.mk
@@ -69,7 +69,26 @@ ${SUBDIR}: .PHONY
     depend distribute lint maninstall manlint \
     obj objlink realinstall regress tags \
     ${SUBDIR_TARGETS}
+.ifdef SUBDIR_PARALLEL
+.for __dir in ${SUBDIR}
+${__target}: ${__target}_subdir_${__dir}
+${__target}_subdir_${__dir}: .MAKE
+	@${_+_}set -e; \
+		if test -d ${.CURDIR}/${__dir}.${MACHINE_ARCH}; then \
+			${ECHODIR} "===> ${DIRPRFX}${__dir}.${MACHINE_ARCH} (${__target:realinstall=install})"; \
+			edir=${__dir}.${MACHINE_ARCH}; \
+			cd ${.CURDIR}/$${edir}; \
+		else \
+			${ECHODIR} "===> ${DIRPRFX}${__dir} (${__target:realinstall=install})"; \
+			edir=${__dir}; \
+			cd ${.CURDIR}/$${edir}; \
+		fi; \
+		${MAKE} ${__target:realinstall=install} \
+		    DIRPRFX=${DIRPRFX}$$edir/
+.endfor
+.else
 ${__target}: _SUBDIR
+.endif
 .endfor
 
 .for __target in files includes
diff --git a/usr.bin/Makefile b/usr.bin/Makefile
index 6321c4579..8f046bfbc 100644
--- a/usr.bin/Makefile
+++ b/usr.bin/Makefile
@@ -393,4 +393,6 @@ _smbutil=	smbutil
 _smbutil=	smbutil
 .endif
 
+SUBDIR_PARALLEL=
+
 .include <bsd.subdir.mk>
diff --git a/usr.sbin/Makefile b/usr.sbin/Makefile
index 0a88bf14d..75fa704d8 100644
--- a/usr.sbin/Makefile
+++ b/usr.sbin/Makefile
@@ -520,4 +520,6 @@ _eeprom=	eeprom
 _ofwdump=	ofwdump
 .endif
 
+SUBDIR_PARALLEL=
+
 .include <bsd.subdir.mk>
-- 
2.45.0