parallel-subdirs.mak: snippet to include in Makefiles to build subdirectories in...

Build sub-directories in parallel if make -jN is used. We'll descend
into the sub-directories a second time after the first parallel run,
but at that point there shouldn't be anything left to do. Assumes
there are no dependencies between any of the sub-directories.

diff --git a/parallel-subdirs.mak b/parallel-subdirs.mak
new file mode 100644 (file)
index 0000000..36885df
--- /dev/null
+++ b/parallel-subdirs.mak
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+# include this at the end of $MODULE/ext/Makefile.am to force make to
+# build subdirectories in parallel when make -jN is used. We will end up
+# descending into all subdirectories a second time, but only after the first
+# (parallel) run has finished, so it should go right through the second time.
+
+.PHONY: independent-subdirs $(SUBDIRS)
+
+independent-subdirs: $(SUBDIRS)
+
+$(SUBDIRS):
+       $(MAKE) -C $@
+
+all-recursive: independent-subdirs