From: Andrii Nakryiko <andrii@kernel.org>
To: bpf@vger.kernel.org, ast@kernel.org, daniel@iogearbox.net,
martin.lau@kernel.org
Cc: andrii@kernel.org, kernel-team@meta.com
Subject: [PATCH v2 bpf-next] selftests/bpf: make multi-uprobe tests work in RELEASE=1 mode
Date: Fri, 29 Mar 2024 12:04:10 -0700 [thread overview]
Message-ID: <20240329190410.4191353-1-andrii@kernel.org> (raw)
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>
---
tools/testing/selftests/bpf/Makefile | 2 +-
tools/testing/selftests/bpf/uprobe_multi.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index 3b9eb40d6343..b0ac3dd80acf 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -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 \
diff --git a/tools/testing/selftests/bpf/uprobe_multi.c b/tools/testing/selftests/bpf/uprobe_multi.c
index a61ceab60b68..7ffa563ffeba 100644
--- a/tools/testing/selftests/bpf/uprobe_multi.c
+++ b/tools/testing/selftests/bpf/uprobe_multi.c
@@ -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)
--
2.43.0
next reply other threads:[~2024-03-29 19:04 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-29 19:04 Andrii Nakryiko [this message]
2024-03-30 0:20 ` [PATCH v2 bpf-next] selftests/bpf: make multi-uprobe tests work in RELEASE=1 mode patchwork-bot+netdevbpf
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