| Message ID | patch-v3-5.9-16f2e3ff35b-20220225T090127Z-avarab@gmail.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | Makefile: optimize noop runs, add shared.mak | expand |
Ævar Arnfjörð Bjarmason <avarab@gmail.com> writes: > This was added in 30248886ce8 (Makefile: disable default implicit > rules, 2010-01-26), let's move it to the top of "shared.mak" so it'll > apply to all our Makefiles. > > This doesn't benefit the main Makefile at all, since it already had > the rule, but since we're including shared.mak in other Makefiles > starts to benefit them. E.g. running the 'man" target is now faster: Nice.
diff --git a/Makefile b/Makefile index 185bfa71df3..1462016a3f4 100644 --- a/Makefile +++ b/Makefile @@ -2580,8 +2580,6 @@ ASM_SRC := $(wildcard $(OBJECTS:o=S)) ASM_OBJ := $(ASM_SRC:S=o) C_OBJ := $(filter-out $(ASM_OBJ),$(OBJECTS)) -.SUFFIXES: - $(C_OBJ): %.o: %.c GIT-CFLAGS $(missing_dep_dirs) $(missing_compdb_dir) $(QUIET_CC)$(CC) -o $*.o -c $(dep_args) $(compdb_args) $(ALL_CFLAGS) $(EXTRA_CPPFLAGS) $< $(ASM_OBJ): %.o: %.S GIT-CFLAGS $(missing_dep_dirs) $(missing_compdb_dir) diff --git a/shared.mak b/shared.mak index 29f0e69ecb9..1dda948df09 100644 --- a/shared.mak +++ b/shared.mak @@ -9,6 +9,11 @@ %:: s.% %:: SCCS/s.% +## Likewise delete default $(SUFFIXES). See: +## +## info make --index-search=.SUFFIXES +.SUFFIXES: + ### Flags affecting all rules # A GNU make extension since gmake 3.72 (released in late 1994) to
This was added in 30248886ce8 (Makefile: disable default implicit rules, 2010-01-26), let's move it to the top of "shared.mak" so it'll apply to all our Makefiles. This doesn't benefit the main Makefile at all, since it already had the rule, but since we're including shared.mak in other Makefiles starts to benefit them. E.g. running the 'man" target is now faster: $ git -c hyperfine.hook.setup= hyperfine -L rev HEAD~1,HEAD~0 -s 'make -C Documentation man' 'make -C Documentation -j1 man' Benchmark 1: make -C Documentation -j1 man' in 'HEAD~1 Time (mean ± σ): 121.7 ms ± 8.8 ms [User: 105.8 ms, System: 18.6 ms] Range (min … max): 112.8 ms … 148.4 ms 26 runs Benchmark 2: make -C Documentation -j1 man' in 'HEAD~0 Time (mean ± σ): 97.5 ms ± 8.0 ms [User: 80.1 ms, System: 20.1 ms] Range (min … max): 89.8 ms … 111.8 ms 32 runs Summary 'make -C Documentation -j1 man' in 'HEAD~0' ran 1.25 ± 0.14 times faster than 'make -C Documentation -j1 man' in 'HEAD~1' The reason for that can be seen when comparing that run with "--debug=a". Without this change making a target like "git-status.1" will cause "make" to consider not only "git-status.txt", but "git-status.txt.o", as well as numerous other implicit suffixes such as ".c", ".cc", ".cpp" etc. See [1] for a more detailed before/after example. So this is causing us to omit a bunch of work we didn't need to do. For making "git-status.1" the "--debug=a" output is reduced from ~140k lines to ~6k. 1. https://lore.kernel.org/git/220222.86bkyz875k.gmgdl@evledraar.gmail.com/ Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> --- Makefile | 2 -- shared.mak | 5 +++++ 2 files changed, 5 insertions(+), 2 deletions(-)