Commit 844f7315 authored by Ihor Solodrai's avatar Ihor Solodrai Committed by Andrii Nakryiko
Browse files

selftests/bpf: Use auto-dependencies for test objects 



Make use of -M compiler options when building .test.o objects to
generate .d files and avoid re-building all tests every time.

Previously, if a single test bpf program under selftests/bpf/progs/*.c
has changed, make would rebuild all the *.bpf.o, *.skel.h and *.test.o
objects, which is a lot of unnecessary work.

A typical dependency chain is:
progs/x.c -> x.bpf.o -> x.skel.h -> x.test.o -> trunner_binary

However for many tests it's not a 1:1 mapping by name, and so far
%.test.o have been simply dependent on all %.skel.h files, and
%.skel.h files on all %.bpf.o objects.

Avoid full rebuilds by instructing the compiler (via -MMD) to
produce *.d files with real dependencies, and appropriately including
them. Exploit make feature that rebuilds included makefiles if they
were changed by setting %.test.d as prerequisite for %.test.o files.

A couple of examples of compilation time speedup (after the first
clean build):

$ touch progs/verifier_and.c && time make -j8
Before: real	0m16.651s
After:  real	0m2.245s
$ touch progs/read_vsyscall.c && time make -j8
Before: real	0m15.743s
After:  real	0m1.575s

A drawback of this change is that now there is an overhead due to make
processing lots of .d files, which potentially may slow down unrelated
targets. However a time to make all from scratch hasn't changed
significantly:

$ make clean && time make -j8
Before: real	1m31.148s
After:  real	1m30.309s

Suggested-by: default avatarEduard Zingerman <eddyz87@gmail.com>
Signed-off-by: default avatarIhor Solodrai <ihor.solodrai@pm.me>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/VJihUTnvtwEgv_mOnpfy7EgD9D2MPNoHO-MlANeLIzLJPGhDeyOuGKIYyKgk0O6KPjfM-MuhtvPwZcngN8WFqbTnTRyCSMc2aMZ1ODm1T_g=@pm.me
parent f157f9cb

tools/testing/selftests/bpf/.gitignore

+1 −0
Original line number Diff line number Diff line
@@ -31,6 +31,7 @@ test_tcp_check_syncookie_user 
test_sysctl

xdping

test_cpp

*.d

*.subskel.h

*.skel.h

*.lskel.h

tools/testing/selftests/bpf/Makefile

+32 −11
Original line number Diff line number Diff line
@@ -477,7 +477,8 @@ xsk_xdp_progs.skel.h-deps := xsk_xdp_progs.bpf.o 
xdp_hw_metadata.skel.h-deps := xdp_hw_metadata.bpf.o

xdp_features.skel.h-deps := xdp_features.bpf.o



LINKED_BPF_SRCS := $(patsubst %.bpf.o,%.c,$(foreach skel,$(LINKED_SKELS),$($(skel)-deps)))

LINKED_BPF_OBJS := $(foreach skel,$(LINKED_SKELS),$($(skel)-deps))

LINKED_BPF_SRCS := $(patsubst %.bpf.o,%.c,$(LINKED_BPF_OBJS))



# Set up extra TRUNNER_XXX "temporary" variables in the environment (relies on

# $eval()) and pass control to DEFINE_TEST_RUNNER_RULES.
@@ -556,7 +557,11 @@ $(TRUNNER_BPF_LSKELS): %.lskel.h: %.bpf.o $(BPFTOOL) | $(TRUNNER_OUTPUT) 
	$(Q)$$(BPFTOOL) gen skeleton -L $$(<:.o=.llinked3.o) name $$(notdir $$(<:.bpf.o=_lskel)) > $$@

	$(Q)rm -f $$(<:.o=.llinked1.o) $$(<:.o=.llinked2.o) $$(<:.o=.llinked3.o)



$(TRUNNER_BPF_SKELS_LINKED): $(TRUNNER_BPF_OBJS) $(BPFTOOL) | $(TRUNNER_OUTPUT)

$(LINKED_BPF_OBJS): %: $(TRUNNER_OUTPUT)/%



# .SECONDEXPANSION here allows to correctly expand %-deps variables as prerequisites

.SECONDEXPANSION:

$(TRUNNER_BPF_SKELS_LINKED): $(TRUNNER_OUTPUT)/%: $$$$(%-deps) $(BPFTOOL) | $(TRUNNER_OUTPUT)

	$$(call msg,LINK-BPF,$(TRUNNER_BINARY),$$(@:.skel.h=.bpf.o))

	$(Q)$$(BPFTOOL) gen object $$(@:.skel.h=.linked1.o) $$(addprefix $(TRUNNER_OUTPUT)/,$$($$(@F)-deps))

	$(Q)$$(BPFTOOL) gen object $$(@:.skel.h=.linked2.o) $$(@:.skel.h=.linked1.o)
@@ -566,6 +571,14 @@ $(TRUNNER_BPF_SKELS_LINKED): $(TRUNNER_BPF_OBJS) $(BPFTOOL) | $(TRUNNER_OUTPUT) 
	$(Q)$$(BPFTOOL) gen skeleton $$(@:.skel.h=.linked3.o) name $$(notdir $$(@:.skel.h=)) > $$@

	$(Q)$$(BPFTOOL) gen subskeleton $$(@:.skel.h=.linked3.o) name $$(notdir $$(@:.skel.h=)) > $$(@:.skel.h=.subskel.h)

	$(Q)rm -f $$(@:.skel.h=.linked1.o) $$(@:.skel.h=.linked2.o) $$(@:.skel.h=.linked3.o)



# When the compiler generates a %.d file, only skel basenames (not

# full paths) are specified as prerequisites for corresponding %.o

# file. This target makes %.skel.h basename dependent on full paths,

# linking generated %.d dependency with actual %.skel.h files.

$(notdir %.skel.h): $(TRUNNER_OUTPUT)/%.skel.h

	@true



endif



# ensure we set up tests.h header generation rule just once
@@ -582,15 +595,20 @@ endif 
# compile individual test files

# Note: we cd into output directory to ensure embedded BPF object is found

$(TRUNNER_TEST_OBJS): $(TRUNNER_OUTPUT)/%.test.o:			\

		      $(TRUNNER_TESTS_DIR)/%.c				\

		      $(TRUNNER_OUTPUT)/%.test.d

	$$(call msg,TEST-OBJ,$(TRUNNER_BINARY),$$@)

	$(Q)cd $$(@D) && $$(CC) -I. $$(CFLAGS) -MMD -MT $$@ -c $(CURDIR)/$$< $$(LDLIBS) -o $$(@F)



$(TRUNNER_TEST_OBJS:.o=.d): $(TRUNNER_OUTPUT)/%.test.d:			\

			    $(TRUNNER_TESTS_DIR)/%.c			\

			    $(TRUNNER_EXTRA_HDRS)			\

		      $(TRUNNER_BPF_OBJS)				\

			    $(TRUNNER_BPF_SKELS)			\

			    $(TRUNNER_BPF_LSKELS)			\

			    $(TRUNNER_BPF_SKELS_LINKED)			\

			    $$(BPFOBJ) | $(TRUNNER_OUTPUT)

	$$(call msg,TEST-OBJ,$(TRUNNER_BINARY),$$@)

	$(Q)cd $$(@D) && $$(CC) -I. $$(CFLAGS) -c $(CURDIR)/$$< $$(LDLIBS) -o $$(@F)



include $(wildcard $(TRUNNER_TEST_OBJS:.o=.d))



$(TRUNNER_EXTRA_OBJS): $(TRUNNER_OUTPUT)/%.o:				\

		       %.c						\
@@ -608,6 +626,9 @@ ifneq ($2:$(OUTPUT),:$(shell pwd)) 
	$(Q)rsync -aq $$^ $(TRUNNER_OUTPUT)/

endif



# some X.test.o files have runtime dependencies on Y.bpf.o files

$(OUTPUT)/$(TRUNNER_BINARY): | $(TRUNNER_BPF_OBJS)



$(OUTPUT)/$(TRUNNER_BINARY): $(TRUNNER_TEST_OBJS)			\

			     $(TRUNNER_EXTRA_OBJS) $$(BPFOBJ)		\

			     $(RESOLVE_BTFIDS)				\
@@ -769,7 +790,7 @@ $(OUTPUT)/uprobe_multi: uprobe_multi.c 
EXTRA_CLEAN := $(SCRATCH_DIR) $(HOST_SCRATCH_DIR)			\

	prog_tests/tests.h map_tests/tests.h verifier/tests.h		\

	feature bpftool 						\

	$(addprefix $(OUTPUT)/,*.o *.skel.h *.lskel.h *.subskel.h	\

	$(addprefix $(OUTPUT)/,*.o *.d *.skel.h *.lskel.h *.subskel.h	\

			       no_alu32 cpuv4 bpf_gcc bpf_testmod.ko	\

			       bpf_test_no_cfi.ko			\

			       liburandom_read.so)