On Thu, Jul 18, 2024 at 3:57 PM Ihor Solodrai <ihor.solodrai@xxxxx> wrote: > > 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@xxxxxxxxx> > Signed-off-by: Ihor Solodrai <ihor.solodrai@xxxxx> > > --- > v3 -> v4: Make $(TRUNNER_BPF_OBJS) order only prereq of trunner binary > v2 -> v3: Restore dependency on $(TRUNNER_BPF_OBJS) > v1 -> v2: Make %.test.d prerequisite order only > --- > tools/testing/selftests/bpf/.gitignore | 1 + > tools/testing/selftests/bpf/Makefile | 44 +++++++++++++++++++------- > 2 files changed, 34 insertions(+), 11 deletions(-) > It seems to behave correctly, but it reports wrong flavor when building .bpf.o, e.g.,: $ touch progs/test_vmlinux.c $ make -j90 CLNG-BPF [test_maps] test_vmlinux.bpf.o CLNG-BPF [test_maps] test_vmlinux.bpf.o CLNG-BPF [test_maps] test_vmlinux.bpf.o GEN-SKEL [test_progs] test_vmlinux.skel.h GEN-SKEL [test_progs-cpuv4] test_vmlinux.skel.h GEN-SKEL [test_progs-no_alu32] test_vmlinux.skel.h TEST-OBJ [test_progs] vmlinux.test.o TEST-OBJ [test_progs-no_alu32] vmlinux.test.o EXT-COPY [test_progs-no_alu32] urandom_read bpf_testmod.ko bpf_test_no_cfi.ko liburandom_read.so xdp_synproxy sign-file uprobe_multi ima_setup.sh verify_sig_setup.sh btf_dump_test_case_bitfields.c btf_dump_test_case_multidim.c btf_dump_test_case_namespacing.c btf_dump_test_case_ordering.c btf_dump_test_case_packing.c btf_dump_test_case_padding.c btf_dump_test_case_syntax.c TEST-OBJ [test_progs-cpuv4] vmlinux.test.o EXT-COPY [test_progs-cpuv4] urandom_read bpf_testmod.ko bpf_test_no_cfi.ko liburandom_read.so xdp_synproxy sign-file uprobe_multi ima_setup.sh verify_sig_setup.sh btf_dump_test_case_bitfields.c btf_dump_test_case_multidim.c btf_dump_test_case_namespacing.c btf_dump_test_case_ordering.c btf_dump_test_case_packing.c btf_dump_test_case_padding.c btf_dump_test_case_syntax.c make[1]: Nothing to be done for 'docs'. BINARY test_progs BINARY test_progs-no_alu32 BINARY test_progs-cpuv4 $ ls -la test_vmlinux.bpf.o no_alu32/test_vmlinux.bpf.o cpuv4/test_vmlinux.bpf.o -rw-r--r-- 1 andriin users 21344 Jul 19 11:08 cpuv4/test_vmlinux.bpf.o -rw-r--r-- 1 andriin users 21408 Jul 19 11:08 no_alu32/test_vmlinux.bpf.o -rw-r--r-- 1 andriin users 21408 Jul 19 11:08 test_vmlinux.bpf.o Note [test_maps] for all three variants (I expected test_maps/test_progs + no_alu32 + cpuv4, just like we see for skel.h). Can you please double check what's going on? Looking at timestamps it seems like they are actually regenerated, though. BTW, if you get a chance, see if you can avoid unnecessary EXT-COPY as well (probably a bit smarter rule dependency should be set up, e.g., phony target that then depends on actual files or something like that). Regardless, this is a massive improvement and seems to work correctly, so I've applied this and will wait for follow ups. Thanks a lot! BTW, are you planning to look into vmlinux.h optimization as well? > diff --git a/tools/testing/selftests/bpf/.gitignore b/tools/testing/selftests/bpf/.gitignore > index 5025401323af..4e4aae8aa7ec 100644 > --- a/tools/testing/selftests/bpf/.gitignore > +++ b/tools/testing/selftests/bpf/.gitignore > @@ -31,6 +31,7 @@ test_tcp_check_syncookie_user > test_sysctl > xdping > test_cpp > +*.d > *.subskel.h > *.skel.h > *.lskel.h [...]
