Messages in this thread Patch in this message | | | From | Song Liu <> | Subject | Re: [RFC] perf/core: allow ftrace for functions in kernel/event/core.c | Date | Fri, 24 Sep 2021 17:15:01 +0000 |
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> On Jun 5, 2020, at 3:02 PM, Steven Rostedt <rostedt@goodmis.org> wrote: > > On Fri, 5 Jun 2020 21:58:48 +0000 > Song Liu <songliubraving@fb.com> wrote: > >> >> How does this work in your tests? > > I started it, but got distracted by other work. It did not crash with > the little testing I did do. I wanted to also look at my patch that > adds tracing to the ftrace directory too. > > I'll try to remember to address this some more next week. Feel free to > ping me again then.
It looks like we dropped the ball more than a year ago.
Adding Andrii and KP, who both hit this limitation in their recent work. I also hit this again recently. I was trying to use kernel live patch to fix a perf issue, but realized the whole kernel/events directory is not ftrace-able. :(
Hi Steven,
I am not sure whether you have got chance to test it more thoroughly. Optimistically assuming it didn't crash easily :-) , what would you suggest for our next steps?
Thanks, Song
Attaching the original RFC/PATCH below.
From: Song Liu <songliubraving@fb.com> Subject: [RFC] perf/core: allow ftrace for functions in kernel/event/core.c
It is useful to trace functions in kernel/event/core.c. Allow ftrace for them by removing $(CC_FLAGS_FTRACE) from Makefile.
Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Steven Rostedt (VMware) <rostedt@goodmis.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Alexey Budankov <alexey.budankov@linux.intel.com> Signed-off-by: Song Liu <songliubraving@fb.com> --- kernel/events/Makefile | 5 ----- 1 file changed, 5 deletions(-)
diff --git a/kernel/events/Makefile b/kernel/events/Makefile index 3c022e33c109..8591c180b52b 100644 --- a/kernel/events/Makefile +++ b/kernel/events/Makefile @@ -1,10 +1,5 @@ # SPDX-License-Identifier: GPL-2.0 -ifdef CONFIG_FUNCTION_TRACER -CFLAGS_REMOVE_core.o =3D $(CC_FLAGS_FTRACE) -endif - obj-y :=3D core.o ring_buffer.o callchain.o =20 obj-$(CONFIG_HAVE_HW_BREAKPOINT) +=3D hw_breakpoint.o obj-$(CONFIG_UPROBES) +=3D uprobes.o - --=20 2.24.1
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