%.bpf.o objects depend on vmlinux.h, which makes them transitively dependent on unnecessary libbpf headers. However vmlinux.h doesn't actually change as often. Compute and save vmlinux.h checksum, and change $(TRUNNER_BPF_OBJS) dependencies so that they are rebuilt only if vmlinux.h contents was changed. Also explicitly list libbpf headers required for test progs. Example of build time improvement (after first clean build): $ touch ../../../lib/bpf/bpf.h $ time make -j8 Before: real 1m37.592s After: real 0m27.310s You may notice that the speed gain is caused by skipping %.bpf.o gen. Link: https://lore.kernel.org/bpf/CAEf4BzY1z5cC7BKye8=A8aTVxpsCzD=p1jdTfKC7i0XVuYoHUQ@xxxxxxxxxxxxxx Signed-off-by: Ihor Solodrai <ihor.solodrai@xxxxx> --- tools/testing/selftests/bpf/Makefile | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-) diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile index ec7d425c4022..4f23d9ddc8b8 100644 --- a/tools/testing/selftests/bpf/Makefile +++ b/tools/testing/selftests/bpf/Makefile @@ -407,6 +407,14 @@ else $(Q)cp "$(VMLINUX_H)" $@ endif +VMLINUX_H_CHECKSUM := $(INCLUDE_DIR)/vmlinux.h.md5 + +$(VMLINUX_H_CHECKSUM): $(INCLUDE_DIR)/vmlinux.h + $(shell md5sum $(INCLUDE_DIR)/vmlinux.h > .tmp.md5) + $(shell md5sum -c .tmp.md5 $(VMLINUX_H_CHECKSUM) --status \ + || cp -f .tmp.md5 $(VMLINUX_H_CHECKSUM)) + $(shell rm .tmp.md5) + $(RESOLVE_BTFIDS): $(HOST_BPFOBJ) | $(HOST_BUILD_DIR)/resolve_btfids \ $(TOOLSDIR)/bpf/resolve_btfids/main.c \ $(TOOLSDIR)/lib/rbtree.c \ @@ -515,6 +523,12 @@ xdp_features.skel.h-deps := xdp_features.bpf.o LINKED_BPF_OBJS := $(foreach skel,$(LINKED_SKELS),$($(skel)-deps)) LINKED_BPF_SRCS := $(patsubst %.bpf.o,%.c,$(LINKED_BPF_OBJS)) +HEADERS_FOR_BPF_OBJS := $(wildcard $(BPFDIR)/*.bpf.h) \ + $(addprefix $(BPFDIR)/, bpf_core_read.h \ + bpf_endian.h \ + bpf_helpers.h \ + bpf_tracing.h) + # Set up extra TRUNNER_XXX "temporary" variables in the environment (relies on # $eval()) and pass control to DEFINE_TEST_RUNNER_RULES. # Parameters: @@ -564,9 +578,8 @@ $(TRUNNER_BPF_PROGS_DIR)$(if $2,-)$2-bpfobjs := y $(TRUNNER_BPF_OBJS): $(TRUNNER_OUTPUT)/%.bpf.o: \ $(TRUNNER_BPF_PROGS_DIR)/%.c \ $(TRUNNER_BPF_PROGS_DIR)/*.h \ - $$(INCLUDE_DIR)/vmlinux.h \ - $(wildcard $(BPFDIR)/bpf_*.h) \ - $(wildcard $(BPFDIR)/*.bpf.h) \ + $(VMLINUX_H_CHECKSUM) \ + $(HEADERS_FOR_BPF_OBJS) \ | $(TRUNNER_OUTPUT) $$(BPFOBJ) $$(call $(TRUNNER_BPF_BUILD_RULE),$$<,$$@, \ $(TRUNNER_BPF_CFLAGS) \ -- 2.34.1
