linux-kernel - Re: [PATCH] ring-buffer: Use a housekeeping CPU to wake up waiters

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20260109111506.66ad545a@gandalf.local.home>
Date: Fri, 9 Jan 2026 11:15:06 -0500
From: Steven Rostedt <rostedt@...dmis.org>
To: Petr Tesarik <ptesarik@...e.com>
Cc: Masami Hiramatsu <mhiramat@...nel.org>, Mathieu Desnoyers
 <mathieu.desnoyers@...icios.com>, Sebastian Andrzej Siewior
 <bigeasy@...utronix.de>, Clark Williams <clrkwllms@...nel.org>,
 linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org,
 linux-rt-devel@...ts.linux.dev
Subject: Re: [PATCH] ring-buffer: Use a housekeeping CPU to wake up waiters

On Fri, 9 Jan 2026 09:57:56 +0100
Petr Tesarik <ptesarik@...e.com> wrote:

> I have removed both "inline" and "noinline" in v2, leaving it at the
> discretion of the compiler. If you believe it deserves a "noinline",
> feel free to add it. FWIW on x86-64, I didn't observe any measurable
> diference either in latency or instruction cache footprint.

Please add the noinline. I went through and added strategic "noinline" and
"__always_inline", as well as placing "likely()" and "unlikely()" and
dropped the cost of adding an event from just under 300ns down to less than
150ns.

This code is called during function tracing (hit at every function call),
and yes, every little bit helps!

-- Steve