Hi Masahiro-san, On 11/09/2017 11:41 PM, Masahiro Yamada wrote: > 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 resulted > obj-dirs is as many "./" as objects. > > For those 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 bad code in arch/x86/entry/vdso/Makefile. This is now > really unnecessary. > > Signed-off-by: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx> > --- > > arch/x86/entry/vdso/Makefile | 4 ---- > scripts/Makefile.build | 15 ++++++--------- > scripts/Makefile.host | 11 ----------- > scripts/Makefile.lib | 5 ----- > 4 files changed, 6 insertions(+), 29 deletions(-) > > diff --git a/arch/x86/entry/vdso/Makefile b/arch/x86/entry/vdso/Makefile > index d540966..f8e3d85 100644 > --- a/arch/x86/entry/vdso/Makefile > +++ b/arch/x86/entry/vdso/Makefile > @@ -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)) $(obj)/vdso32/ > - > targets += vdso32/vdso32.lds > targets += vdso32/note.o vdso32/system_call.o vdso32/sigreturn.o > targets += vdso32/vclock_gettime.o > diff --git a/scripts/Makefile.build b/scripts/Makefile.build > index 62d5314..89ac180 100644 > --- a/scripts/Makefile.build > +++ b/scripts/Makefile.build > @@ -64,15 +64,6 @@ ifneq ($(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 directory does not exist > +obj-dirs := $(sort $(obj) $(patsubst %/,%, $(dir $(targets)))) > +$(shell mkdir -p $(obj-dirs)) > +endif > + I just take a quick glance: is "$(obj)" here necessary? I think all $(targets) are under directory $(obj) when we descend into $(obj) to recursive make, if I don't miss anything. -- Sincerely, Cao jin > # 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. > > diff --git a/scripts/Makefile.host b/scripts/Makefile.host > index 9cfd5c8..3a5460d 100644 > --- a/scripts/Makefile.host > +++ b/scripts/Makefile.host > @@ -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)) > @@ -68,8 +59,6 @@ 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 > > diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib > index 4d88ad7..5fbc46d 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 > -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
