* [PATCH v2] perf build: Make libunwind opt-in rather than opt-out
@ 2024-10-28 19:36 Ian Rogers
2024-10-28 21:49 ` Arnaldo Carvalho de Melo
2024-11-05 16:41 ` Namhyung Kim
0 siblings, 2 replies; 3+ messages in thread
From: Ian Rogers @ 2024-10-28 19:36 UTC (permalink / raw)
To: Peter Zijlstra, Ingo Molnar, Arnaldo Carvalho de Melo,
Namhyung Kim, Mark Rutland, Alexander Shishkin, Jiri Olsa,
Ian Rogers, Adrian Hunter, Kan Liang, linux-perf-users,
linux-kernel
Having multiple unwinding libraries makes the perf code harder to
understand and we have unused/untested code paths.
Perf made BPF support an opt-out rather than opt-in feature. As libbpf
has a libelf dependency, elfutils that provides libelf will also
provide libdw. When libdw is present perf will use libdw unwinding
rather than libunwind unwinding even if libunwind support is compiled
in.
Rather than have libunwind built into perf and never used, explicitly
disable the support and make it opt-in.
Signed-off-by: Ian Rogers <irogers@google.com>
Closes: https://lore.kernel.org/linux-perf-users/CAP-5=fUXkp-d7gkzX4eF+nbjb2978dZsiHZ9abGHN=BN1qAcbg@mail.gmail.com/
---
v2: update build tests.
---
tools/perf/Makefile.config | 4 ++++
tools/perf/Makefile.perf | 2 +-
tools/perf/tests/make | 6 +++---
3 files changed, 8 insertions(+), 4 deletions(-)
diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
index b93ed2b7623f..707d7355ff18 100644
--- a/tools/perf/Makefile.config
+++ b/tools/perf/Makefile.config
@@ -91,6 +91,10 @@ ifneq ($(SRCARCH),$(filter $(SRCARCH),x86 arm arm64 powerpc s390 csky riscv loon
NO_LIBDW_DWARF_UNWIND := 1
endif
+ifneq ($(LIBUNWIND),1)
+ NO_LIBUNWIND := 1
+endif
+
ifeq ($(LIBUNWIND_LIBS),)
NO_LIBUNWIND := 1
endif
diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf
index b4dee7c20ed1..d74241a15131 100644
--- a/tools/perf/Makefile.perf
+++ b/tools/perf/Makefile.perf
@@ -52,7 +52,7 @@ include ../scripts/utilities.mak
#
# Define NO_LIBELF if you do not want libelf dependency (e.g. cross-builds)
#
-# Define NO_LIBUNWIND if you do not want libunwind dependency for dwarf
+# Define LIBUNWIND if you do not want libunwind dependency for dwarf
# backtrace post unwind.
#
# Define NO_BACKTRACE if you do not want stack backtrace debug feature
diff --git a/tools/perf/tests/make b/tools/perf/tests/make
index a5040772043f..a7fcbd589752 100644
--- a/tools/perf/tests/make
+++ b/tools/perf/tests/make
@@ -81,7 +81,7 @@ make_no_gtk2 := NO_GTK2=1
make_no_ui := NO_SLANG=1 NO_GTK2=1
make_no_demangle := NO_DEMANGLE=1
make_no_libelf := NO_LIBELF=1
-make_no_libunwind := NO_LIBUNWIND=1
+make_libunwind := LIBUNWIND=1
make_no_libdw_dwarf_unwind := NO_LIBDW_DWARF_UNWIND=1
make_no_backtrace := NO_BACKTRACE=1
make_no_libcapstone := NO_CAPSTONE=1
@@ -121,7 +121,7 @@ make_static := LDFLAGS=-static NO_PERF_READ_VDSO32=1 NO_PERF_READ_VDSOX3
# all the NO_* variable combined
make_minimal := NO_LIBPERL=1 NO_LIBPYTHON=1 NO_GTK2=1
-make_minimal += NO_DEMANGLE=1 NO_LIBELF=1 NO_LIBUNWIND=1 NO_BACKTRACE=1
+make_minimal += NO_DEMANGLE=1 NO_LIBELF=1 NO_BACKTRACE=1
make_minimal += NO_LIBNUMA=1 NO_LIBAUDIT=1 NO_LIBBIONIC=1
make_minimal += NO_LIBDW_DWARF_UNWIND=1 NO_AUXTRACE=1 NO_LIBBPF=1
make_minimal += NO_LIBCRYPTO=1 NO_SDT=1 NO_JVMTI=1 NO_LIBZSTD=1
@@ -153,7 +153,7 @@ run += make_no_gtk2
run += make_no_ui
run += make_no_demangle
run += make_no_libelf
-run += make_no_libunwind
+run += make_libunwind
run += make_no_libdw_dwarf_unwind
run += make_no_backtrace
run += make_no_libcapstone
--
2.47.0.163.g1226f6d8fa-goog
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH v2] perf build: Make libunwind opt-in rather than opt-out
2024-10-28 19:36 [PATCH v2] perf build: Make libunwind opt-in rather than opt-out Ian Rogers
@ 2024-10-28 21:49 ` Arnaldo Carvalho de Melo
2024-11-05 16:41 ` Namhyung Kim
1 sibling, 0 replies; 3+ messages in thread
From: Arnaldo Carvalho de Melo @ 2024-10-28 21:49 UTC (permalink / raw)
To: Ian Rogers
Cc: Peter Zijlstra, Ingo Molnar, Namhyung Kim, Mark Rutland,
Alexander Shishkin, Jiri Olsa, Adrian Hunter, Kan Liang,
linux-perf-users, linux-kernel
On Mon, Oct 28, 2024 at 12:36:19PM -0700, Ian Rogers wrote:
> Having multiple unwinding libraries makes the perf code harder to
> understand and we have unused/untested code paths.
> Perf made BPF support an opt-out rather than opt-in feature. As libbpf
> has a libelf dependency, elfutils that provides libelf will also
> provide libdw. When libdw is present perf will use libdw unwinding
> rather than libunwind unwinding even if libunwind support is compiled
> in.
> Rather than have libunwind built into perf and never used, explicitly
> disable the support and make it opt-in.
Looks ok and testing it does what is advertised:
⬢ [acme@toolbox perf-tools-next]$ ldd ~/bin/perf | grep libunwind
⬢ [acme@toolbox perf-tools-next]$ perf check feature libunwind
libunwind: [ OFF ] # HAVE_LIBUNWIND_SUPPORT
⬢ [acme@toolbox perf-tools-next]$
Since I have libunwind-devel installed:
Auto-detecting system features:
<SNIP
... libunwind: [ on ]
<SNIP
If I uninstall libunwind-devel, just to complete the cycle, even this
patch not touching that part:
Auto-detecting system features:
<SNIP>
... libunwind: [ OFF ]
<SNIP>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
- Arnaldo
> Signed-off-by: Ian Rogers <irogers@google.com>
> Closes: https://lore.kernel.org/linux-perf-users/CAP-5=fUXkp-d7gkzX4eF+nbjb2978dZsiHZ9abGHN=BN1qAcbg@mail.gmail.com/
> ---
> v2: update build tests.
> ---
> tools/perf/Makefile.config | 4 ++++
> tools/perf/Makefile.perf | 2 +-
> tools/perf/tests/make | 6 +++---
> 3 files changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
> index b93ed2b7623f..707d7355ff18 100644
> --- a/tools/perf/Makefile.config
> +++ b/tools/perf/Makefile.config
> @@ -91,6 +91,10 @@ ifneq ($(SRCARCH),$(filter $(SRCARCH),x86 arm arm64 powerpc s390 csky riscv loon
> NO_LIBDW_DWARF_UNWIND := 1
> endif
>
> +ifneq ($(LIBUNWIND),1)
> + NO_LIBUNWIND := 1
> +endif
> +
> ifeq ($(LIBUNWIND_LIBS),)
> NO_LIBUNWIND := 1
> endif
> diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf
> index b4dee7c20ed1..d74241a15131 100644
> --- a/tools/perf/Makefile.perf
> +++ b/tools/perf/Makefile.perf
> @@ -52,7 +52,7 @@ include ../scripts/utilities.mak
> #
> # Define NO_LIBELF if you do not want libelf dependency (e.g. cross-builds)
> #
> -# Define NO_LIBUNWIND if you do not want libunwind dependency for dwarf
> +# Define LIBUNWIND if you do not want libunwind dependency for dwarf
> # backtrace post unwind.
> #
> # Define NO_BACKTRACE if you do not want stack backtrace debug feature
> diff --git a/tools/perf/tests/make b/tools/perf/tests/make
> index a5040772043f..a7fcbd589752 100644
> --- a/tools/perf/tests/make
> +++ b/tools/perf/tests/make
> @@ -81,7 +81,7 @@ make_no_gtk2 := NO_GTK2=1
> make_no_ui := NO_SLANG=1 NO_GTK2=1
> make_no_demangle := NO_DEMANGLE=1
> make_no_libelf := NO_LIBELF=1
> -make_no_libunwind := NO_LIBUNWIND=1
> +make_libunwind := LIBUNWIND=1
> make_no_libdw_dwarf_unwind := NO_LIBDW_DWARF_UNWIND=1
> make_no_backtrace := NO_BACKTRACE=1
> make_no_libcapstone := NO_CAPSTONE=1
> @@ -121,7 +121,7 @@ make_static := LDFLAGS=-static NO_PERF_READ_VDSO32=1 NO_PERF_READ_VDSOX3
>
> # all the NO_* variable combined
> make_minimal := NO_LIBPERL=1 NO_LIBPYTHON=1 NO_GTK2=1
> -make_minimal += NO_DEMANGLE=1 NO_LIBELF=1 NO_LIBUNWIND=1 NO_BACKTRACE=1
> +make_minimal += NO_DEMANGLE=1 NO_LIBELF=1 NO_BACKTRACE=1
> make_minimal += NO_LIBNUMA=1 NO_LIBAUDIT=1 NO_LIBBIONIC=1
> make_minimal += NO_LIBDW_DWARF_UNWIND=1 NO_AUXTRACE=1 NO_LIBBPF=1
> make_minimal += NO_LIBCRYPTO=1 NO_SDT=1 NO_JVMTI=1 NO_LIBZSTD=1
> @@ -153,7 +153,7 @@ run += make_no_gtk2
> run += make_no_ui
> run += make_no_demangle
> run += make_no_libelf
> -run += make_no_libunwind
> +run += make_libunwind
> run += make_no_libdw_dwarf_unwind
> run += make_no_backtrace
> run += make_no_libcapstone
> --
> 2.47.0.163.g1226f6d8fa-goog
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH v2] perf build: Make libunwind opt-in rather than opt-out
2024-10-28 19:36 [PATCH v2] perf build: Make libunwind opt-in rather than opt-out Ian Rogers
2024-10-28 21:49 ` Arnaldo Carvalho de Melo
@ 2024-11-05 16:41 ` Namhyung Kim
1 sibling, 0 replies; 3+ messages in thread
From: Namhyung Kim @ 2024-11-05 16:41 UTC (permalink / raw)
To: Peter Zijlstra, Ingo Molnar, Arnaldo Carvalho de Melo,
Mark Rutland, Alexander Shishkin, Jiri Olsa, Adrian Hunter,
Kan Liang, linux-perf-users, linux-kernel, Ian Rogers
On Mon, 28 Oct 2024 12:36:19 -0700, Ian Rogers wrote:
> Having multiple unwinding libraries makes the perf code harder to
> understand and we have unused/untested code paths.
>
> Perf made BPF support an opt-out rather than opt-in feature. As libbpf
> has a libelf dependency, elfutils that provides libelf will also
> provide libdw. When libdw is present perf will use libdw unwinding
> rather than libunwind unwinding even if libunwind support is compiled
> in.
>
> [...]
Applied to perf-tools-next, thanks!
Best regards,
Namhyung
^ permalink raw reply [flat|nested] 3+ messages in thread
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2024-11-05 16:41 ` Namhyung Kim
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