Kernel/linux-next
1
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git synced 2024-12-29 17:22:07 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

kbuild: create object directories simpler and faster

Browse Source 
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>
This commit is contained in:
Masahiro Yamada 2017-11-13 19:29:37 +09:00
parent 591f668997
commit 8a78756eb5
4 changed files with 6 additions and 30 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
arch/x86/entry/vdso/Makefile
View File

@ -129,10 +129,6 @@ $(obj)/vdsox32.so.dbg: $(src)/vdsox32.lds $(vobjx32s) FORCE
CPPFLAGS_vdso32.lds = $(CPPFLAGS_vdso.lds)
VDSO_LDFLAGS_vdso32.lds = -m32 -Wl,-m,elf_i386 -Wl,-soname=linux-gate.so.1
# This makes sure the $(obj) subdirectory exists even though vdso32/
# is not a kbuild sub-make subdirectory.
override obj-dirs = $(dir $(obj)) $(obj)/vdso32/
targets += vdso32/vdso32.lds
targets += vdso32/note.o vdso32/system_call.o vdso32/sigreturn.o
targets += vdso32/vclock_gettime.o

15
scripts/Makefile.build
View File

@ -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.

12
scripts/Makefile.host
View File

@ -48,15 +48,6 @@ host-cxxobjs := $(sort $(foreach m,$(host-cxxmulti),$($(m)-cxxobjs)))
host-cshobjs := $(sort $(foreach m,$(host-cshlib),$($(m:.so=-objs))))
host-cxxshobjs := $(sort $(foreach m,$(host-cxxshlib),$($(m:.so=-objs))))
# output directory for programs/.o files
# hostprogs-y := tools/build may have been specified.
# Retrieve also directory of .o files from prog-objs or prog-cxxobjs notation
host-objdirs := $(dir $(__hostprogs) $(host-cobjs) $(host-cxxobjs))
host-objdirs := $(strip $(sort $(filter-out ./,$(host-objdirs))))
__hostprogs := $(addprefix $(obj)/,$(__hostprogs))
host-csingle := $(addprefix $(obj)/,$(host-csingle))
host-cmulti := $(addprefix $(obj)/,$(host-cmulti))
host-cobjs := $(addprefix $(obj)/,$(host-cobjs))
@ -66,9 +57,6 @@ host-cshlib := $(addprefix $(obj)/,$(host-cshlib))
host-cxxshlib := $(addprefix $(obj)/,$(host-cxxshlib))
host-cshobjs := $(addprefix $(obj)/,$(host-cshobjs))
host-cxxshobjs := $(addprefix $(obj)/,$(host-cxxshobjs))
host-objdirs := $(addprefix $(obj)/,$(host-objdirs))
obj-dirs += $(host-objdirs)
#####
# Handle options to gcc. Support building with separate output directory

5
scripts/Makefile.lib
View File

@ -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