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From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>, Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>,
	Network Development <netdev@vger.kernel.org>,
	bpf <bpf@vger.kernel.org>, lkml <linux-kernel@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>,
	Steven Rostedt <rostedt@goodmis.org>,
	"Naveen N. Rao" <naveen.n.rao@linux.ibm.com>,
	Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>,
	"David S. Miller" <davem@davemloft.net>
Subject: Re: [RFC 00/13] kprobe/bpf: Add support to attach multiple kprobes
Date: Thu, 6 Jan 2022 16:20:05 -0800	[thread overview]
Message-ID: <CAADnVQ+mZxxm=96pQ4ekV3rbjV=svPOKg3TG+K0396g+iMjTbA@mail.gmail.com> (raw)
In-Reply-To: <20220107085203.14f9c06e0537ea6b00779842@kernel.org>

On Thu, Jan 6, 2022 at 3:52 PM Masami Hiramatsu <mhiramat@kernel.org> wrote:
>
> On Thu, 6 Jan 2022 09:40:17 -0800
> Alexei Starovoitov <alexei.starovoitov@gmail.com> wrote:
>
> > On Thu, Jan 6, 2022 at 5:59 AM Masami Hiramatsu <mhiramat@kernel.org> wrote:
> > >
> > > That seems to bind your mind. The program type is just a programing
> > > 'model' of the bpf. You can choose the best implementation to provide
> > > equal functionality. 'kprobe' in bpf is just a name that you call some
> > > instrumentations which can probe kernel code.
> >
> > No. We're not going to call it "fprobe" or any other name.
> > From bpf user's pov it's going to be "multi attach kprobe",
> > because this is how everyone got to know kprobes.
> > The 99% usage is at the beginning of the funcs.
> > When users say "kprobe" they don't care how kernel attaches it.
> > The func entry limitation for "multi attach kprobe" is a no-brainer.
>
> Agreed. I think I might mislead you. From the bpf user pov, it always be
> shown as 'multi attached kprobes (but only for the function entry)'
> the 'fprobe' is kernel internal API name.
>
> > And we need both "multi attach kprobe" and "multi attach kretprobe"
> > at the same time. It's no go to implement one first and the other
> > some time later.
>
> You can provide the interface to user space, but the kernel implementation
> is optimized step by step. We can start it with using real multiple
> kretprobes, and then, switch to 'fprobe' after integrating fgraph
> callback. :)

Sounds good to me.
My point was that users often want to say:
"profile speed of all foo* functions".
To perform such a command a tracer would need to
attach kprobes and kretprobes to all such functions.
The speed of attach/detach has to be fast.
Currently tracers artificially limit the regex just because
attach/detach is so slow that the user will likely Ctrl-C
instead of waiting for many seconds.

  reply	other threads:[~2022-01-07  0:20 UTC|newest]

Thread overview: 54+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-01-04  8:09 [RFC 00/13] kprobe/bpf: Add support to attach multiple kprobes Jiri Olsa
2022-01-04  8:09 ` [PATCH 01/13] ftrace: Add ftrace_set_filter_ips function Jiri Olsa
2022-01-04  8:09 ` [PATCH 02/13] kprobe: Keep traced function address Jiri Olsa
2022-01-05 14:32   ` Masami Hiramatsu
2022-01-06  8:30     ` Jiri Olsa
2022-01-06  4:30   ` Andrii Nakryiko
2022-01-06  8:31     ` Jiri Olsa
2022-01-04  8:09 ` [PATCH 03/13] kprobe: Add support to register multiple ftrace kprobes Jiri Olsa
2022-01-05 15:00   ` Masami Hiramatsu
2022-01-04  8:09 ` [PATCH 04/13] kprobe: Add support to register multiple ftrace kretprobes Jiri Olsa
2022-01-04  8:09 ` [PATCH 05/13] kprobe: Allow to get traced function address for multi ftrace kprobes Jiri Olsa
2022-01-06  4:30   ` Andrii Nakryiko
2022-01-04  8:09 ` [PATCH 06/13] samples/kprobes: Add support for multi kprobe interface Jiri Olsa
2022-01-04  8:09 ` [PATCH 07/13] samples/kprobes: Add support for multi kretprobe interface Jiri Olsa
2022-01-04  8:09 ` [PATCH 08/13] bpf: Add kprobe link for attaching raw kprobes Jiri Olsa
2022-01-06  4:30   ` Andrii Nakryiko
2022-01-06  8:41     ` Jiri Olsa
2022-01-06 16:32       ` Alexei Starovoitov
2022-01-06 21:53         ` Andrii Nakryiko
2022-01-04  8:09 ` [PATCH 09/13] libbpf: Add libbpf__kallsyms_parse function Jiri Olsa
2022-01-04  8:09 ` [PATCH 10/13] libbpf: Add bpf_link_create support for multi kprobes Jiri Olsa
2022-01-04  8:09 ` [PATCH 11/13] libbpf: Add bpf_program__attach_kprobe_opts " Jiri Olsa
2022-01-04  8:09 ` [PATCH 12/13] selftest/bpf: Add raw kprobe attach test Jiri Olsa
2022-01-04  8:09 ` [PATCH 13/13] selftest/bpf: Add bpf_cookie test for raw_k[ret]probe Jiri Olsa
2022-01-04 18:53 ` [RFC 00/13] kprobe/bpf: Add support to attach multiple kprobes Alexei Starovoitov
2022-01-05  9:15   ` Jiri Olsa
2022-01-05 15:24 ` Masami Hiramatsu
2022-01-06  8:29   ` Jiri Olsa
2022-01-06 13:59     ` Masami Hiramatsu
2022-01-06 14:57       ` Jiri Olsa
2022-01-07  5:42         ` Masami Hiramatsu
2022-01-06 15:02       ` Steven Rostedt
2022-01-06 17:40       ` Alexei Starovoitov
2022-01-06 23:52         ` Masami Hiramatsu
2022-01-07  0:20           ` Alexei Starovoitov [this message]
2022-01-07 12:55             ` Masami Hiramatsu
2022-01-11 15:00 ` [RFC PATCH 0/6] fprobe: Introduce fprobe function entry/exit probe Masami Hiramatsu
2022-01-11 15:00   ` [RFC PATCH 1/6] fprobe: Add ftrace based probe APIs Masami Hiramatsu
2022-01-11 15:00   ` [RFC PATCH 2/6] rethook: Add a generic return hook Masami Hiramatsu
2022-01-11 15:00   ` [RFC PATCH 3/6] rethook: x86: Add rethook x86 implementation Masami Hiramatsu
2022-01-11 15:01   ` [RFC PATCH 4/6] fprobe: Add exit_handler support Masami Hiramatsu
2022-01-12 22:28     ` kernel test robot
2022-01-13  2:29     ` kernel test robot
2022-01-13  2:29       ` kernel test robot
2022-01-24 22:24     ` kernel test robot
2022-01-11 15:01   ` [RFC PATCH 5/6] fprobe: Add sample program for fprobe Masami Hiramatsu
2022-01-11 15:01   ` [RFC PATCH 6/6] bpf: Add kprobe link for attaching raw kprobes Masami Hiramatsu
2022-01-12 22:18     ` kernel test robot
2022-01-12 23:19     ` kernel test robot
2022-01-12 23:19       ` kernel test robot
2022-01-12 23:40     ` kernel test robot
2022-01-11 22:39   ` [RFC PATCH 0/6] fprobe: Introduce fprobe function entry/exit probe Alexei Starovoitov
2022-01-12  7:33     ` Masami Hiramatsu
2022-01-12 11:08       ` Masami Hiramatsu

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