From 8a78756eb545a6fb8007fa154a626ca2bc208027 Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Mon, 13 Nov 2017 19:29:37 +0900 Subject: kbuild: create object directories simpler and faster For the out-of-tree build, scripts/Makefile.build creates output directories, but this operation is not efficient. scripts/Makefile.lib calculates obj-dirs as follows: obj-dirs := $(dir $(multi-objs) $(obj-y)) Please notice $(sort ...) is not used here. Usually the result is as many "./" as objects here. For a lot of duplicated paths, the following command is invoked. _dummy := $(foreach d,$(obj-dirs), $(shell [ -d $(d) ] || mkdir -p $(d))) Then, the costly shell command is run over and over again. I see many points for optimization: [1] Use $(sort ...) to cut down duplicated paths before passing them to system call [2] Use single $(shell ...) instead of repeating it with $(foreach ...) This will reduce forking. [3] We can calculate obj-dirs more simply. Most of objects are already accumulated in $(targets). So, $(dir $(targets)) is fine and more comprehensive. I also removed ugly code in arch/x86/entry/vdso/Makefile. This is now really unnecessary. Signed-off-by: Masahiro Yamada Acked-by: Ingo Molnar Tested-by: Douglas Anderson --- scripts/Makefile.lib | 5 ----- 1 file changed, 5 deletions(-) (limited to 'scripts/Makefile.lib') diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib index 4d88ad70fd96..5fbc46daa0f8 100644 --- a/scripts/Makefile.lib +++ b/scripts/Makefile.lib @@ -50,15 +50,11 @@ single-used-m := $(sort $(filter-out $(multi-used-m),$(obj-m))) # objects depend on those (obviously) multi-objs-y := $(foreach m, $(multi-used-y), $($(m:.o=-objs)) $($(m:.o=-y))) multi-objs-m := $(foreach m, $(multi-used-m), $($(m:.o=-objs)) $($(m:.o=-y))) -multi-objs := $(multi-objs-y) $(multi-objs-m) # $(subdir-obj-y) is the list of objects in $(obj-y) which uses dir/ to # tell kbuild to descend subdir-obj-y := $(filter %/built-in.o, $(obj-y)) -# $(obj-dirs) is a list of directories that contain object files -obj-dirs := $(dir $(multi-objs) $(obj-y)) - # Replace multi-part objects by their individual parts, look at local dir only real-objs-y := $(foreach m, $(filter-out $(subdir-obj-y), $(obj-y)), $(if $(strip $($(m:.o=-objs)) $($(m:.o=-y))),$($(m:.o=-objs)) $($(m:.o=-y)),$(m))) $(extra-y) real-objs-m := $(foreach m, $(obj-m), $(if $(strip $($(m:.o=-objs)) $($(m:.o=-y)) $($(m:.o=-m))),$($(m:.o=-objs)) $($(m:.o=-y)) $($(m:.o=-m)),$(m))) @@ -81,7 +77,6 @@ multi-used-m := $(addprefix $(obj)/,$(multi-used-m)) multi-objs-y := $(addprefix $(obj)/,$(multi-objs-y)) multi-objs-m := $(addprefix $(obj)/,$(multi-objs-m)) subdir-ym := $(addprefix $(obj)/,$(subdir-ym)) -obj-dirs := $(addprefix $(obj)/,$(obj-dirs)) # These flags are needed for modversions and compiling, so we define them here # $(modname_flags) defines KBUILD_MODNAME as the name of the module it will -- cgit v1.2.1