linux-kernel - Re: [PATCH bpf-next v3] bpf: make the attach target more accurate

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Message-ID: <CAADnVQKmUE3_5RHDFLmKzNSDkLD=Z2g3bkfT2aRsPkFiMPd-4Q@mail.gmail.com>
Date: Mon, 14 Jul 2025 12:52:28 -0700
From: Alexei Starovoitov <alexei.starovoitov@...il.com>
To: Menglong Dong <menglong8.dong@...il.com>
Cc: Alexei Starovoitov <ast@...nel.org>, Daniel Borkmann <daniel@...earbox.net>, 
	John Fastabend <john.fastabend@...il.com>, Andrii Nakryiko <andrii@...nel.org>, 
	Martin KaFai Lau <martin.lau@...ux.dev>, Eduard <eddyz87@...il.com>, Song Liu <song@...nel.org>, 
	Yonghong Song <yonghong.song@...ux.dev>, KP Singh <kpsingh@...nel.org>, 
	Stanislav Fomichev <sdf@...ichev.me>, Hao Luo <haoluo@...gle.com>, Jiri Olsa <jolsa@...nel.org>, 
	bpf <bpf@...r.kernel.org>, LKML <linux-kernel@...r.kernel.org>, 
	Menglong Dong <dongml2@...natelecom.cn>
Subject: Re: [PATCH bpf-next v3] bpf: make the attach target more accurate

On Thu, Jul 10, 2025 at 12:10 AM Menglong Dong <menglong8.dong@...il.com> wrote:
>                         } else {
> -                               addr = kallsyms_lookup_name(tname);
> +                               ret = bpf_lookup_attach_addr(NULL, tname, &addr);
>                         }

Not sure why your benchmarking doesn't show the difference,
but above is a big regression.
kallsyms_lookup_name() is a binary search whereas your
bpf_lookup_attach_addr() is linear.
You should see a massive degradation in multi-kprobe attach speeds.

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