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authorMasahiro Yamada <yamada.masahiro@socionext.com>2017-11-13 13:29:37 +0300
committerMasahiro Yamada <yamada.masahiro@socionext.com>2017-11-16 03:07:35 +0300
commit8a78756eb545a6fb8007fa154a626ca2bc208027 (patch)
treea5f6f791cf742128df2d9af0cfba1393cae0b0c4 /scripts/Makefile.build
parent591f66899784ae0afa13ff9a3eb5ce0a4358e48b (diff)
downloadlinux-8a78756eb545a6fb8007fa154a626ca2bc208027.tar.xz
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 $(targets)) is fine and more comprehensive. I also removed ugly code in arch/x86/entry/vdso/Makefile. This is now really unnecessary. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Acked-by: Ingo Molnar <mingo@kernel.org> Tested-by: Douglas Anderson <dianders@chromium.org>
Diffstat (limited to 'scripts/Makefile.build')
-rw-r--r--scripts/Makefile.build15
1 files changed, 6 insertions, 9 deletions
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 6f603770b08e..496ecd825c71 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -64,15 +64,6 @@ ifneq ($(hostprogs-y)$(hostprogs-m)$(hostlibs-y)$(hostlibs-m)$(hostcxxlibs-y)$(h
include scripts/Makefile.host
endif
-ifneq ($(KBUILD_SRC),)
-# Create output directory if not already present
-_dummy := $(shell [ -d $(obj) ] || mkdir -p $(obj))
-
-# Create directories for object files if directory does not exist
-# Needed when obj-y := dir/file.o syntax is used
-_dummy := $(foreach d,$(obj-dirs), $(shell [ -d $(d) ] || mkdir -p $(d)))
-endif
-
ifndef obj
$(warning kbuild: Makefile.build is included improperly)
endif
@@ -589,6 +580,12 @@ ifneq ($(cmd_files),)
include $(cmd_files)
endif
+ifneq ($(KBUILD_SRC),)
+# Create directories for object files if they do not exist
+obj-dirs := $(sort $(obj) $(patsubst %/,%, $(dir $(targets))))
+$(shell mkdir -p $(obj-dirs))
+endif
+
# Declare the contents of the .PHONY variable as phony. We keep that
# information in a variable se we can use it in if_changed and friends.