Commit bd74370b authored Apr 30, 2017 by Rabin Vincent Committed by Masahiro Yamada May 03, 2017

Makefile: evaluate LDFLAGS_BUILD_ID only once



Evaluate LDFLAGS_BUILD_ID (which involves invoking the compiler) only
once instead of over and over.

This provides a ~20% reduction in null build time with x86 allnoconfig:

$ make allnoconfig && make -j8
$ perf stat -r5 -e sched:sched_process_exec make -j8
-       2 119      sched:sched_process_exec
+       1 878      sched:sched_process_exec

-       1,238817018 seconds time elapsed
+       0,971020553 seconds time elapsed

Signed-off-by: Rabin Vincent <rabin@rab.in>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

parent e8a3118e

Makefile

+1 −1

Original line number	Diff line number	Diff line
		@@ -829,7 +829,7 @@ KBUILD_AFLAGS += $(ARCH_AFLAGS) $(KAFLAGS)
		KBUILD_CFLAGS += $(ARCH_CFLAGS) $(KCFLAGS)

		# Use --build-id when available.
		LDFLAGS_BUILD_ID = $(patsubst -Wl$(comma)%,%,\
		LDFLAGS_BUILD_ID := $(patsubst -Wl$(comma)%,%,\
		$(call cc-ldoption, -Wl$(comma)--build-id,))
		KBUILD_LDFLAGS_MODULE += $(LDFLAGS_BUILD_ID)
		LDFLAGS_vmlinux += $(LDFLAGS_BUILD_ID)