From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <SRS1=k69q=kernel.org==Nw5j=BG=goodmis.org=rostedt@sourceware.org>
Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1])
	by sourceware.org (Postfix) with ESMTPS id B30733858C41
	for <libc-alpha@sourceware.org>; Wed, 17 May 2023 18:36:55 +0000 (GMT)
DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org B30733858C41
Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=goodmis.org
Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=kernel.org
Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140])
	(using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits))
	(No client certificate requested)
	by dfw.source.kernel.org (Postfix) with ESMTPS id 42C3664A0F;
	Wed, 17 May 2023 18:36:55 +0000 (UTC)
Received: by smtp.kernel.org (Postfix) with ESMTPSA id 701ACC433D2;
	Wed, 17 May 2023 18:36:52 +0000 (UTC)
Date: Wed, 17 May 2023 14:36:50 -0400
From: Steven Rostedt <rostedt@goodmis.org>
To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Peter Zijlstra <peterz@infradead.org>, linux-kernel@vger.kernel.org,
 Thomas Gleixner <tglx@linutronix.de>, "Paul E . McKenney"
 <paulmck@kernel.org>, Boqun Feng <boqun.feng@gmail.com>, "H . Peter Anvin"
 <hpa@zytor.com>, Paul Turner <pjt@google.com>, linux-api@vger.kernel.org,
 Christian Brauner <brauner@kernel.org>, Florian Weimer <fw@deneb.enyo.de>,
 David.Laight@ACULAB.COM, carlos@redhat.com, Peter Oskolkov <posk@posk.io>,
 Alexander Mikhalitsyn <alexander@mihalicyn.com>, Chris Kennelly
 <ckennelly@google.com>, Ingo Molnar <mingo@redhat.com>, Darren Hart
 <dvhart@infradead.org>, Davidlohr Bueso <dave@stgolabs.net>,
 =?UTF-8?B?QW5kcsOp?= Almeida <andrealmeid@igalia.com>,
 libc-alpha@sourceware.org, Jonathan Corbet <corbet@lwn.net>
Subject: Re: [RFC PATCH 0/4] Extend rseq with sched_state field
Message-ID: <20230517143650.55eb8ce7@gandalf.local.home>
In-Reply-To: <20230517152654.7193-1-mathieu.desnoyers@efficios.com>
References: <20230517152654.7193-1-mathieu.desnoyers@efficios.com>
X-Mailer: Claws Mail 3.17.8 (GTK+ 2.24.33; x86_64-pc-linux-gnu)
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: quoted-printable
X-Spam-Status: No, score=-2.3 required=5.0 tests=BAYES_00,HEADER_FROM_DIFFERENT_DOMAINS,KAM_DMARC_STATUS,SPF_HELO_NONE,SPF_PASS,TXREP,T_SCC_BODY_TEXT_LINE autolearn=no autolearn_force=no version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org
List-Id: <libc-alpha.sourceware.org>

On Wed, 17 May 2023 11:26:50 -0400
Mathieu Desnoyers <mathieu.desnoyers@efficios.com> wrote:

> This prototype extends struct rseq with a new sched_state field, which
> contains a "on-cpu" flag kept up-to-date by the scheduler.
>=20
> It is meant to be used by userspace adaptative mutexes to decide between
> busy-wait and futex wait system call (releasing the CPU) behaviors based
> on the current state of the mutex owner.

Woot!

I'm so glad I talked Jon into hanging around for Andr=C3=A9's spurious talk.
He's the one that brought up rseq (as he mentioned in his article), and I
guess you read that :-)

Unfortunately, I'm in the process of a lot of trips and
meetings/presentations over the next few weeks, and I will not be able to
look into this. But I hope that Andr=C3=A9 could test it out.

Cheers!

-- Steve