From: Steven Rostedt <rostedt@goodmis.org>
To: Jiri Olsa <olsajiri@gmail.com>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
Ingo Molnar <mingo@redhat.com>, bpf <bpf@vger.kernel.org>,
Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
Yonghong Song <yhs@fb.com>,
John Fastabend <john.fastabend@gmail.com>,
KP Singh <kpsingh@chromium.org>,
Stanislav Fomichev <sdf@google.com>, Hao Luo <haoluo@google.com>
Subject: Re: [RFC] ftrace: Add support to keep some functions out of ftrace
Date: Fri, 22 Jul 2022 23:53:58 -0400 [thread overview]
Message-ID: <20220722235358.0eaa62d0@rorschach.local.home> (raw)
In-Reply-To: <20220722174120.688768a3@gandalf.local.home>
On Fri, 22 Jul 2022 17:41:20 -0400
Steven Rostedt <rostedt@goodmis.org> wrote:
> > I think I understand the fentry/ftrace equivalence you see, I remember
> > the perl mcount script ;-)
>
> It's even more than that. We worked with the compiler folks to get fentry
> for ftrace purposes (namely to speed it up, and not rely on frame
> pointers, which mcount did). fentry never existed until then. Like I said.
> fentry was created *for* ftrace. And currently it's x86 specific, as it
> relies on the calling convention that a call does both, push the return
> address onto the stack, and jump to a function. The blr
> (branch-link-register) method is more complex, which is where the
> "patchable" work comes from.
If you are interested in more details about the birth of fentry, here's
the email that started it all:
https://lore.kernel.org/lkml/1258657614.22249.824.camel@gandalf.stny.rr.com/
-- Steve
next prev parent reply other threads:[~2022-07-23 3:54 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-22 11:08 [RFC] ftrace: Add support to keep some functions out of ftrace Jiri Olsa
2022-07-22 11:26 ` Steven Rostedt
2022-07-22 16:04 ` Alexei Starovoitov
2022-07-22 16:08 ` Steven Rostedt
2022-07-22 16:25 ` Steven Rostedt
2022-07-22 16:53 ` Alexei Starovoitov
2022-07-22 17:14 ` Steven Rostedt
2022-07-22 21:05 ` Jiri Olsa
2022-07-22 21:41 ` Steven Rostedt
2022-07-23 3:53 ` Steven Rostedt [this message]
2022-07-23 3:56 ` Steven Rostedt
2022-07-25 7:00 ` Jiri Olsa
2022-07-23 21:39 ` Jiri Olsa
2022-08-12 21:18 ` Jiri Olsa
2022-08-12 21:50 ` Steven Rostedt
2022-08-13 19:02 ` Steven Rostedt
2022-08-14 11:32 ` Steven Rostedt
2022-08-14 15:22 ` Jiri Olsa
2022-08-15 2:07 ` Chen Zhongjin
2022-08-15 8:04 ` Jiri Olsa
2022-08-15 11:01 ` Björn Töpel
2022-08-15 11:29 ` Jiri Olsa
2022-08-15 12:19 ` Björn Töpel
2022-08-15 12:30 ` Björn Töpel
2022-08-15 8:03 ` Peter Zijlstra
2022-08-15 9:44 ` Jiri Olsa
2022-08-15 12:37 ` Peter Zijlstra
2022-08-15 14:25 ` Alexei Starovoitov
2022-08-15 14:33 ` Peter Zijlstra
2022-08-15 14:45 ` Alexei Starovoitov
2022-08-15 15:02 ` Peter Zijlstra
2022-08-15 15:17 ` Alexei Starovoitov
2022-08-15 15:28 ` Peter Zijlstra
2022-08-15 15:35 ` Alexei Starovoitov
2022-08-15 15:44 ` Steven Rostedt
2022-08-15 15:53 ` Alexei Starovoitov
2022-08-15 16:13 ` Steven Rostedt
2022-08-15 15:48 ` Peter Zijlstra
2022-08-16 6:56 ` Jiri Olsa
2022-08-17 9:29 ` Jiri Olsa
2022-08-17 16:57 ` Alexei Starovoitov
2022-08-17 19:39 ` Jiri Olsa
2022-08-15 15:41 ` Peter Zijlstra
2022-08-15 15:49 ` Alexei Starovoitov
2022-08-15 16:08 ` Steven Rostedt
2022-08-18 20:27 ` Jiri Olsa
2022-08-18 20:50 ` Steven Rostedt
2022-08-18 21:00 ` Alexei Starovoitov
2022-08-18 21:05 ` Steven Rostedt
2022-08-18 21:32 ` Jiri Olsa
2022-08-19 11:45 ` Jiri Olsa
2022-08-23 17:23 ` Alexei Starovoitov
2022-08-26 8:00 ` Jiri Olsa
2022-08-18 21:14 ` Jiri Olsa
2022-08-15 15:32 ` Steven Rostedt
2022-07-22 16:26 ` Jiri Olsa
2022-07-22 16:37 ` Steven Rostedt
2022-07-22 16:54 ` Alexei Starovoitov
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