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| author | Ihor Solodrai <ihor.solodrai@pm.me> | 2024-08-28 17:46:23 +0000 |
|---|---|---|
| committer | Andrii Nakryiko <andrii@kernel.org> | 2024-08-30 11:54:14 -0700 |
| commit | 2ad6d23f465a4f851e3bcf6d74c315ce7b2c205b (patch) | |
| tree | 3000c6c0a7ffede66896137e75d7205270bc2ce0 | |
| parent | 38960ac8f916d1e60d4ceb4735a93740c4308d9c (diff) | |
selftests/bpf: Do not update vmlinux.h unnecessarily
%.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.
When generating vmlinux.h, compare it to a previous version and update
it only if there are changes.
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
Notice that %.bpf.o gen step is skipped if vmlinux.h hasn't changed.
Signed-off-by: Ihor Solodrai <ihor.solodrai@pm.me>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/CAEf4BzY1z5cC7BKye8=A8aTVxpsCzD=p1jdTfKC7i0XVuYoHUQ@mail.gmail.com
Link: https://lore.kernel.org/bpf/20240828174608.377204-2-ihor.solodrai@pm.me
| -rw-r--r-- | tools/testing/selftests/bpf/Makefile | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile index 53cc13b92ee2..7660d19b66c2 100644 --- a/tools/testing/selftests/bpf/Makefile +++ b/tools/testing/selftests/bpf/Makefile @@ -399,10 +399,14 @@ $(HOST_BPFOBJ): $(wildcard $(BPFDIR)/*.[ch] $(BPFDIR)/Makefile) \ DESTDIR=$(HOST_SCRATCH_DIR)/ prefix= all install_headers endif +# vmlinux.h is first dumped to a temprorary file and then compared to +# the previous version. This helps to avoid unnecessary re-builds of +# $(TRUNNER_BPF_OBJS) $(INCLUDE_DIR)/vmlinux.h: $(VMLINUX_BTF) $(BPFTOOL) | $(INCLUDE_DIR) ifeq ($(VMLINUX_H),) $(call msg,GEN,,$@) - $(Q)$(BPFTOOL) btf dump file $(VMLINUX_BTF) format c > $@ + $(Q)$(BPFTOOL) btf dump file $(VMLINUX_BTF) format c > $(INCLUDE_DIR)/.vmlinux.h.tmp + $(Q)cmp -s $(INCLUDE_DIR)/.vmlinux.h.tmp $@ || mv $(INCLUDE_DIR)/.vmlinux.h.tmp $@ else $(call msg,CP,,$@) $(Q)cp "$(VMLINUX_H)" $@ |