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selftests/bpf: Use auto-dependencies for test objects

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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: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Ihor Solodrai <ihor.solodrai@pm.me>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/VJihUTnvtwEgv_mOnpfy7EgD9D2MPNoHO-MlANeLIzLJPGhDeyOuGKIYyKgk0O6KPjfM-MuhtvPwZcngN8WFqbTnTRyCSMc2aMZ1ODm1T_g=@pm.me
This commit is contained in:
Ihor Solodrai 2024-07-18 22:57:43 +00:00 committed by Andrii Nakryiko
parent f157f9cb85
commit 844f7315e7
2 changed files with 33 additions and 11 deletions
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1
tools/testing/selftests/bpf/.gitignore vendored
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@ -31,6 +31,7 @@ test_tcp_check_syncookie_user
test_sysctl
xdping
test_cpp
*.d
*.subskel.h
*.skel.h
*.lskel.h

43
tools/testing/selftests/bpf/Makefile
View File

@ -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
@ -583,14 +596,19 @@ endif
# 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_EXTRA_HDRS) \
$(TRUNNER_BPF_OBJS) \
$(TRUNNER_BPF_SKELS) \
$(TRUNNER_BPF_LSKELS) \
$(TRUNNER_BPF_SKELS_LINKED) \
$$(BPFOBJ) | $(TRUNNER_OUTPUT)
$(TRUNNER_OUTPUT)/%.test.d
$$(call msg,TEST-OBJ,$(TRUNNER_BINARY),$$@)
$(Q)cd $$(@D) && $$(CC) -I. $$(CFLAGS) -c $(CURDIR)/$$< $$(LDLIBS) -o $$(@F)
$(Q)cd $$(@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_SKELS) \
$(TRUNNER_BPF_LSKELS) \
$(TRUNNER_BPF_SKELS_LINKED) \
$$(BPFOBJ) | $(TRUNNER_OUTPUT)
include $(wildcard $(TRUNNER_TEST_OBJS:.o=.d))
$(TRUNNER_EXTRA_OBJS): $(TRUNNER_OUTPUT)/%.o: \
%.c \
@ -608,6 +626,9 @@ ifneq ($2:$(OUTPUT),:$(shell pwd))
$(Q)rsync -aq $$^ $(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) \
@ -768,8 +789,8 @@ $(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 \
feature bpftool \
$(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)