Multi tool use

makefile run targets in parallel

I’ve the following makefile, with two rules.

Is there a way to run these two rules in parallel, I mean to maximize
the core’s capabilities? I see this section but not sure that I got how to use it for my purpose, since I want to handle it within the makefile and not from the command line.

I.e. run module1 & 2 targets in parallel.

This is the makefile:

all: module1 module2

.PHONY: module1
module1:
@echo "run module 1"
DIR=$(PWD)
@echo $(DIR)

.PHONY: module2
module2:
@echo "run module2”

cleanup:
fzr clean $(DIR)


make -j2

make

1 Answer
1

You can set make options that you usually pass to make via its command line invokation in the makefile itself. Add this line to your makefile

make

MAKEFLAGS += -j2


and you can invoke make without the -j flag, it will still spawn two processes to build targets in parallel, when they aren't dependent on each other. To automatically determine the number of jobs to spawn, you can use this on linux

make

-j

NPROCS = $(shell grep -c 'processor' /proc/cpuinfo)
MAKEFLAGS += -j$(NPROCS)


and on MacOS

NPROCS = $(shell sysctl hw.ncpu | grep -o '[0-9]+')
MAKEFLAGS += -j$(NPROCS)


MAKEFLAGS += -j$(shell nproc || printf 1)

|| printf 1

nproc

1

@echo $(NPROCS)

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