linux-kernel - Re: [PATCH bpf-next v2 0/6] bpf trampoline support "jmp" mode

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Message-ID: <5027922.GXAFRqVoOG@7950hx>
Date: Tue, 18 Nov 2025 14:34:34 +0800
From: Menglong Dong <menglong.dong@...ux.dev>
To: Menglong Dong <menglong8.dong@...il.com>,
 Alexei Starovoitov <alexei.starovoitov@...il.com>
Cc: Alexei Starovoitov <ast@...nel.org>, Steven Rostedt <rostedt@...dmis.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>, Masami Hiramatsu <mhiramat@...nel.org>,
 Mark Rutland <mark.rutland@....com>,
 Mathieu Desnoyers <mathieu.desnoyers@...icios.com>, jiang.biao@...ux.dev,
 bpf <bpf@...r.kernel.org>, LKML <linux-kernel@...r.kernel.org>,
 linux-trace-kernel <linux-trace-kernel@...r.kernel.org>
Subject: Re: [PATCH bpf-next v2 0/6] bpf trampoline support "jmp" mode

On 2025/11/18 14:31, Alexei Starovoitov wrote:
> On Sun, Nov 16, 2025 at 7:49 PM Menglong Dong <menglong8.dong@...il.com> wrote:
> >
> > For now, the bpf trampoline is called by the "call" instruction. However,
> > it break the RSB and introduce extra overhead in x86_64 arch.
> 
> Please include performance numbers in the cover letter when you respin.

Hmm...I included a little performance, do you mean more performance
data? Current description:

As we can see above, the RSB is totally balanced. After the modification,
the performance of fexit increases from 76M/s to 130M/s.

> 
>