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Date: Thu, 8 Jun 2023 18:51:42 -0400
From: Steven Rostedt <rostedt@goodmis.org>
To: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>, Alexei Starovoitov <ast@kernel.org>,
 Andrii Nakryiko <andrii.nakryiko@gmail.com>, Daniel Borkmann
 <daniel@iogearbox.net>, Andrii Nakryiko <andrii@kernel.org>,
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 <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>, "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: [PATCH v12 bpf-next 02/12] fprobe: Add ftrace based probe APIs
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On Tue, 15 Mar 2022 23:00:38 +0900
Masami Hiramatsu <mhiramat@kernel.org> wrote:

> +static void fprobe_init(struct fprobe *fp)
> +{
> +	fp->nmissed = 0;
> +	fp->ops.func = fprobe_handler;
> +	fp->ops.flags |= FTRACE_OPS_FL_SAVE_REGS;
> +}
> +

Masami,

I thought one of the advantages of fprobes over kprobes was that it did not
need to use SAVE_REGS, as that causes more overhead than SAVE_ARGS?

If fprobes uses save regs, what is the advantage of it over kprobes?

-- Steve