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From: Masami Hiramatsu <mhiramat@kernel.org>
To: Jiri Olsa <jolsa@redhat.com>
Cc: Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>,
	netdev@vger.kernel.org, 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 00:24:35 +0900	[thread overview]
Message-ID: <20220106002435.d73e4010c93462fbee9ef074@kernel.org> (raw)
In-Reply-To: <20220104080943.113249-1-jolsa@kernel.org>

On Tue,  4 Jan 2022 09:09:30 +0100
Jiri Olsa <jolsa@redhat.com> wrote:

> hi,
> adding support to attach multiple kprobes within single syscall
> and speed up attachment of many kprobes.
> 
> The previous attempt [1] wasn't fast enough, so coming with new
> approach that adds new kprobe interface.

Yes, since register_kprobes() just registers multiple kprobes on
array. This is designed for dozens of kprobes.

> The attachment speed of of this approach (tested in bpftrace)
> is now comparable to ftrace tracer attachment speed.. fast ;-)

Yes, because that if ftrace, not kprobes.

> The limit of this approach is forced by using ftrace as attach
> layer, so it allows only kprobes on function's entry (plus
> return probes).

Note that you also need to multiply the number of instances.

> 
> This patchset contains:
>   - kprobes support to register multiple kprobes with current
>     kprobe API (patches 1 - 8)
>   - bpf support ot create new kprobe link allowing to attach
>     multiple addresses (patches 9 - 14)
> 
> We don't need to care about multiple probes on same functions
> because it's taken care on the ftrace_ops layer.

Hmm, I think there may be a time to split the "kprobe as an 
interface for the software breakpoint" and "kprobe as a wrapper
interface for the callbacks of various instrumentations", like
'raw_kprobe'(or kswbp) and 'kprobes'.
And this may be called as 'fprobe' as ftrace_ops wrapper.
(But if the bpf is enough flexible, this kind of intermediate layer
 may not be needed, it can use ftrace_ops directly, eventually)

Jiri, have you already considered to use ftrace_ops from the
bpf directly? Are there any issues?
(bpf depends on 'kprobe' widely?)

Thank you,

-- 
Masami Hiramatsu <mhiramat@kernel.org>

  parent reply	other threads:[~2022-01-05 15:24 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 [this message]
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
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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