iv/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

selftests/bpf: make multi-uprobe tests work in RELEASE=1 mode

Browse Source 
When BPF selftests are built in RELEASE=1 mode with -O2 optimization
level, uprobe_multi binary, called from multi-uprobe tests is optimized
to the point that all the thousands of target uprobe_multi_func_XXX
functions are eliminated, breaking tests.

So ensure they are preserved by using weak attribute.

But, actually, compiling uprobe_multi binary with -O2 takes a really
long time, and is quite useless (it's not a benchmark). So in addition
to ensuring that uprobe_multi_func_XXX functions are preserved, opt-out
of -O2 explicitly in Makefile and stick to -O0. This saves a lot of
compilation time.

With -O2, just recompiling uprobe_multi:

  $ touch uprobe_multi.c
  $ time make RELEASE=1 -j90
  make RELEASE=1 -j90  291.66s user 2.54s system 99% cpu 4:55.52 total

With -O0:
  $ touch uprobe_multi.c
  $ time make RELEASE=1 -j90
  make RELEASE=1 -j90  22.40s user 1.91s system 99% cpu 24.355 total

5 minutes vs (still slow, but...) 24 seconds.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240329190410.4191353-1-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Andrii Nakryiko 2024-03-29 12:04:10 -07:00 committed by Alexei Starovoitov
parent 59f2f84117
commit 623bdd58be
2 changed files with 2 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
tools/testing/selftests/bpf/Makefile
View File

@ -759,7 +759,7 @@ $(OUTPUT)/veristat: $(OUTPUT)/veristat.o
$(OUTPUT)/uprobe_multi: uprobe_multi.c
$(call msg,BINARY,,$@)
$(Q)$(CC) $(CFLAGS) $(LDFLAGS) $^ $(LDLIBS) -o $@
$(Q)$(CC) $(CFLAGS) -O0 $(LDFLAGS) $^ $(LDLIBS) -o $@
EXTRA_CLEAN := $(SCRATCH_DIR) $(HOST_SCRATCH_DIR) \
prog_tests/tests.h map_tests/tests.h verifier/tests.h \

2
tools/testing/selftests/bpf/uprobe_multi.c
View File

@ -9,7 +9,7 @@
#define NAME(name, idx) PASTE(name, idx)
#define DEF(name, idx) int NAME(name, idx)(void) { return 0; }
#define DEF(name, idx) int __attribute__((weak)) NAME(name, idx)(void) { return 0; }
#define CALL(name, idx) NAME(name, idx)();
#define F(body, name, idx) body(name, idx)