Re: [PATCH] Makefile: evaluate LDFLAGS_BUILD_ID only once

[Masahiro Yamada]

2017-05-01 1:16 GMT+09:00 Rabin Vincent :
> 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 


Applied to linux-kbuild/kbuild.  Thanks!


-- 
Best Regards
Masahiro Yamada

[PATCH] Makefile: evaluate LDFLAGS_BUILD_ID only once

[Rabin Vincent]

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 
---
 Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Makefile b/Makefile
index 779302695453..c78a266594c1 100644
--- a/Makefile
+++ b/Makefile
@@ -815,7 +815,7 @@ 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)
-- 
2.11.0