From: Leon Hwang <leon.hwang@linux.dev>
To: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: bpf@vger.kernel.org, Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
John Fastabend <john.fastabend@gmail.com>,
Andrii Nakryiko <andrii@kernel.org>,
Eduard Zingerman <eddyz87@gmail.com>,
Kumar Kartikeya Dwivedi <memxor@gmail.com>,
Martin KaFai Lau <martin.lau@linux.dev>,
Song Liu <song@kernel.org>,
Yonghong Song <yonghong.song@linux.dev>,
Jiri Olsa <jolsa@kernel.org>,
Emil Tsalapatis <emil@etsalapatis.com>,
Ihor Solodrai <ihor.solodrai@linux.dev>,
Quentin Monnet <qmo@kernel.org>, Shuah Khan <shuah@kernel.org>,
Mykyta Yatsenko <yatsenko@meta.com>,
Avinash Duduskar <avinash.duduskar@gmail.com>,
Anton Protopopov <a.s.protopopov@gmail.com>,
Amery Hung <ameryhung@gmail.com>, Jordan Rife <jordan@jrife.io>,
Rong Tao <rongtao@cestc.cn>, Eyal Birger <eyal.birger@gmail.com>,
Pu Lehui <pulehui@huawei.com>,
Jingguo Tan <tanjingguo@huawei.com>, Lin Ma <malin89@huawei.com>,
linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org,
linux-kselftest@vger.kernel.org
Subject: Re: [PATCH bpf-next 00/13] bpf: Add tracing_multi link support for bpf progs
Date: Tue, 25 Aug 2026 13:15:23 +0800 [thread overview]
Message-ID: <7f18980c-0c15-4862-af1f-f451ca12dac5@linux.dev> (raw)
In-Reply-To: <CAEf4BzZpB-qkhu3SAu5MrYYAT2+ZN8WaXqpmnKruOOdjJOLK2A@mail.gmail.com>
On 25/8/26 04:02, Andrii Nakryiko wrote:
> On Sun, Aug 23, 2026 at 10:00 PM Leon Hwang <leon.hwang@linux.dev> wrote:
>>
>> On 22/8/26 01:46, Andrii Nakryiko wrote:
>>> On Sun, Aug 16, 2026 at 11:20 PM Leon Hwang <leon.hwang@linux.dev> wrote:
>>>>
>>>> On 15/8/26 04:14, Andrii Nakryiko wrote:
>>>>> On Sun, Aug 9, 2026 at 8:01 AM Leon Hwang <leon.hwang@linux.dev> wrote:
>>>>>>
>>>>>> Similar to the tracing_multi link support for kernel functions [1], add
>>>>>> support for bpf progs.
>>>>>>
>>>>>> When attaching to bpf progs, it must attaches to the target by text poke
>>>>>> way.
>>>>>>
>>>>>
>>>>> Please spend a bit more human effort on justification for the change
>>>>> and explaining your use case. In what case you'll be attaching to a
>>>>> large amount of BPF programs such that attachment speed-up (if there
>>>>> is any) matters.
>>>>
>>>> Will update the cover letter with justification and my use case.
>>>>
>>>> Here's my use case:
>>>>
>>>> I'm planning to enhance the function-graph feature of bpfsnoop [1]. It
>>>> will trace all bpf progs, including their subprogs, to draw a full
>>>> function call graph including bpf prog call sites.
>>>>
>>>
>>> fair enough, interesting use case, definitely outline that in the next
>>> revision (and provide before/after attach time as well for such use
>>> case, please)
>>>
>> Will include my use case.
>>
>> Implemented the attachment micro-benchmark. Here's the result on an
>> x86_64 16c16g VM:
>>
>> ./bench tracing-multi-attach-progs
>> Setting up benchmark 'tracing-multi-attach-progs'...
>> tracing-multi-attach-progs: prepared 1000 identical BPF program targets
>> tracing-multi-attach-progs: fentry created and attached 1000
>> programs/links in 679.324ms
>> tracing-multi-attach-progs: fentry.multi created one program and
>> attached one 1000-target link in 470.042ms
>> tracing-multi-attach-progs: fentry.multi creation/attachment speedup is
>> 1.45x
>>
>> The speedup 1.45x looks good. But attaching to 1000 progs via fentry
>
> I'd say "meh". If 500ms is ok, 700ms is not that much more noticeable.
>
Besides the attachment speedup, this series provides a way to attach to
multiple bpf progs via one link. The current revision reuses the
ftrace-based attachment, which relies on
CONFIG_HAVE_SINGLE_FTRACE_DIRECT_OPS. In the next revision, it will get
rid of CONFIG_HAVE_SINGLE_FTRACE_DIRECT_OPS with its own attachment
implementation. Hence, this series will be able to run on those arches
that have trampoline support.
Thanks,
Leon
next prev parent reply other threads:[~2026-08-25 5:15 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-09 15:00 [PATCH bpf-next 00/13] bpf: Add tracing_multi link support for bpf progs Leon Hwang
2026-08-09 15:00 ` [PATCH bpf-next 01/13] bpf: Initialize ftrace_managed in bpf_trampoline_get Leon Hwang
2026-08-09 15:01 ` [PATCH bpf-next 02/13] bpf: Factor out update_fentry_multi helper Leon Hwang
2026-08-09 15:01 ` [PATCH bpf-next 03/13] bpf: Drop unnecessary ftrace_location() in update_fentry_multi() Leon Hwang
2026-08-09 15:01 ` [PATCH bpf-next 04/13] bpf: Add tracing_multi link support for bpf progs Leon Hwang
2026-08-10 13:13 ` Jiri Olsa
2026-08-11 6:12 ` Leon Hwang
2026-08-09 15:01 ` [PATCH bpf-next 05/13] libbpf: " Leon Hwang
2026-08-09 15:01 ` [PATCH bpf-next 06/13] bpf: Add tracing_multi link fdinfo " Leon Hwang
2026-08-09 16:20 ` bot+bpf-ci
2026-08-12 4:04 ` Leon Hwang
2026-08-09 15:01 ` [PATCH bpf-next 07/13] bpf: Add tracing_multi link info " Leon Hwang
2026-08-09 15:01 ` [PATCH bpf-next 08/13] selftests/bpf: Add tracing_multi bpf prog attach test Leon Hwang
2026-08-09 15:01 ` [PATCH bpf-next 09/13] selftests/bpf: Add tracing_multi bpf prog attach failure tests Leon Hwang
2026-08-09 15:01 ` [PATCH bpf-next 10/13] selftests/bpf: Add tracing_multi bpf prog cookie test Leon Hwang
2026-08-09 16:20 ` bot+bpf-ci
2026-08-12 4:06 ` Leon Hwang
2026-08-09 15:01 ` [PATCH bpf-next 11/13] selftests/bpf: Add tracing_multi bpf prog rollback test Leon Hwang
2026-08-09 15:01 ` [PATCH bpf-next 12/13] selftests/bpf: Add tracing_multi bpf prog link info test Leon Hwang
2026-08-09 15:01 ` [PATCH bpf-next 13/13] selftests/bpf: Test tailcall with fentry.multi Leon Hwang
2026-08-14 20:14 ` [PATCH bpf-next 00/13] bpf: Add tracing_multi link support for bpf progs Andrii Nakryiko
2026-08-17 6:20 ` Leon Hwang
2026-08-21 17:46 ` Andrii Nakryiko
2026-08-24 5:00 ` Leon Hwang
2026-08-24 20:02 ` Andrii Nakryiko
2026-08-25 5:15 ` Leon Hwang [this message]
2026-08-25 18:27 ` Andrii Nakryiko
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