On 13.04.2011 14:24, Toralf Förster wrote:
> Hello,
>
> related to the parallel build capabilities I'm wondering how make does
> optimize the build process.
>
Make do not make copy of itself unless you invoke it for recursive build:
SHELL = /bin/sh
parallel-build:
make -C $(dir1) & make -C $(dir2) &
Above example have disadvantage as main Make do not wait for spawned
child processes.
You can simulate parallel building with waiting with GNU xargs utility:
DIR_LIST := $(patsubst %/.,%,$(wildcard */.))
CPUCNT := 4
# $(1) list of subdirs
# $(2) target name
define process-subdirs
for d in $(1); do \
[ -f $$d/Makefile ] && echo $$d || :; \
done | xargs --max-procs=$(CPUCNT) --no-run-if-empty -n 1 make $(2) -C
endef
.PHONY: all
all:
$(call process-subdirs,$(DIR_LIST),$@)
Make can run in parallel independent targets in processing of single
Makefile by -j NUM option.
--
С уважением, Александр Гавенко.
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