From: Steven Rostedt <rostedt@goodmis.org>
To: "Alexei Starovoitov" <alexei.starovoitov@gmail.com>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>,
"Shuah Khan" <shuah@kernel.org>,
"Mathieu Desnoyers" <mathieu.desnoyers@efficios.com>,
<linux-kernel@vger.kernel.org>,
<linux-trace-kernel@vger.kernel.org>,
<linux-kselftest@vger.kernel.org>, <bpf@vger.kernel.org>
Subject: Re: [RFC PATCH 2/4] tracing/probes: Compile all fetchargs into a single BPF program per event
Date: Wed, 1 Jul 2026 14:47:26 -0400 [thread overview]
Message-ID: <20260701144726.0a5f2204@gandalf.local.home> (raw)
In-Reply-To: <DJNGE5JG5ZY4.FEO5DZ21TL7Z@gmail.com>
On Wed, 01 Jul 2026 11:41:26 -0700
"Alexei Starovoitov" <alexei.starovoitov@gmail.com> wrote:
> Nack.
> I really don't like it.
So the nack is mostly your opinion and not technical?
> There were days in the past when the kernel generating bpf directly was appealing.
> These days are gone. Performance improvements for fetchargs is not a good reason
Why is performance *not* a good reason?
> to add all this complexity and bypass verifier checks.
The code lives in the kernel. What reason is there to add verification
checks? The point of verification is because we don't trust user space. Why
do we not trust the kernel?
> bpf insns should come from user space.
Why?
-- Steve
next prev parent reply other threads:[~2026-07-01 18:47 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-01 13:45 [RFC PATCH 0/4] tracing/probes: Optimize fetcharg with BPF Masami Hiramatsu (Google)
2026-07-01 13:45 ` [RFC PATCH 1/4] tools/tracing: Add fetcharg performance micro-benchmark Masami Hiramatsu (Google)
2026-07-01 13:45 ` [RFC PATCH 2/4] tracing/probes: Compile all fetchargs into a single BPF program per event Masami Hiramatsu (Google)
2026-07-01 18:41 ` Alexei Starovoitov
2026-07-01 18:47 ` Steven Rostedt [this message]
2026-07-01 18:53 ` Alexei Starovoitov
2026-07-01 22:40 ` Masami Hiramatsu
2026-07-02 0:01 ` Alexei Starovoitov
2026-07-02 1:01 ` Masami Hiramatsu
2026-07-02 14:04 ` Steven Rostedt
2026-07-01 13:45 ` [RFC PATCH 3/4] tracing: Add disable_bpf trace option to ignore eBPF for fetchargs Masami Hiramatsu (Google)
2026-07-01 13:46 ` [RFC PATCH 4/4] selftests/ftrace: Add a test for eBPF compiled fetchargs Masami Hiramatsu (Google)
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