From: Peter Zijlstra <peterz@infradead.org>
To: Suleiman Souhlal <suleiman@google.com>
Cc: linux-kernel@vger.kernel.org, "Thomas Gleixner" <tglx@kernel.org>,
"Ingo Molnar" <mingo@redhat.com>,
"Darren Hart" <dvhart@infradead.org>,
"Davidlohr Bueso" <dave@stgolabs.net>,
"André Almeida" <andrealmeid@igalia.com>,
"Juri Lelli" <juri.lelli@redhat.com>,
"Vincent Guittot" <vincent.guittot@linaro.org>,
"Dietmar Eggemann" <dietmar.eggemann@arm.com>,
"Steven Rostedt" <rostedt@goodmis.org>,
"Ben Segall" <bsegall@google.com>, "Mel Gorman" <mgorman@suse.de>,
"Valentin Schneider" <vschneid@redhat.com>,
"K Prateek Nayak" <kprateek.nayak@amd.com>,
"zhidao su" <soolaugust@gmail.com>,
"John Stultz" <jstultz@google.com>,
"Qais Yousef" <qyousef@google.com>,
ssouhlal@freebsd.org
Subject: Re: [RFC PATCH 00/12] FUTEX_PING: A stealable futex using Proxy Execution.
Date: Thu, 17 Sep 2026 10:58:05 +0200 [thread overview]
Message-ID: <20260917085805.GD2009045@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <20260917043339.2093426-1-suleiman@google.com>
On Thu, Sep 17, 2026 at 04:33:24AM +0000, Suleiman Souhlal wrote:
> Hello,
>
> This patch series adds a new type of PI futexes, PI Next Generation,
> or PING (name coined by Steven Rostedt) (but other name suggestions
> are welcome!), that differs from classic PI futexes in that they can
> be stolen from the top waiter, and use Proxy Execution instead of
> rtmutexes internally.
>
> The reason to allow the futexes to be stolen is that with classic PI
> futex's strict handoff to the top waiter, new contending lockers are
> now forced to wait in queue, which means that any locking operation
> now becomes a scheduling event. With stealing, a contending locker has
> the chance of taking the lock without blocking. The longer wait time
> of blocked tasks can be mitigated by forcing the lock to be handed
> off to them in a way that can't be stolen, when they've been stolen
> from too much, to ensure they don't get starved.
>
> The use of Proxy Execution lets us also get Priority Inheritance for
> for fair tasks, which PI futexes don't really allow.
https://patch.msgid.link/1490204338-1856-1-git-send-email-longman%40redhat.com
Also, the goal is to eventually delete rt_mutex and have it be the
normal mutex, in which case the existing FUTEX_*_PI things will
automagically work.
So I'm thinking all of this is way premature.
next prev parent reply other threads:[~2026-09-17 8:58 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-17 4:33 Suleiman Souhlal
2026-09-17 4:33 ` [RFC PATCH 01/12] sched: Abstract task_struct->blocked_on by locking primitive Suleiman Souhlal
2026-09-17 4:33 ` [RFC PATCH 02/12] futex: Switch PI futex to use p->pi_futex_lock instead of p->pi_lock Suleiman Souhlal
2026-09-17 15:38 ` Peter Zijlstra
2026-09-17 4:33 ` [RFC PATCH 03/12] futex: Add "ping" parameter to pi_state management functions and export them Suleiman Souhlal
2026-09-17 4:33 ` [RFC PATCH 04/12] futex: Introduce stealable PI futex, FUTEX_*_PING Suleiman Souhlal
2026-09-17 4:33 ` [RFC PATCH 05/12] futex: Implement exit_ping_state_list() Suleiman Souhlal
2026-09-17 4:33 ` [RFC PATCH 06/12] futex: Address aborting from futex_lock_ping() while owning ping_state Suleiman Souhlal
2026-09-17 4:33 ` [RFC PATCH 07/12] futex: Make FUTEX_*_PING use Proxy Execution Suleiman Souhlal
2026-09-17 13:18 ` Jihan LIN
2026-09-17 14:39 ` K Prateek Nayak
2026-09-17 15:36 ` Peter Zijlstra
2026-09-17 4:33 ` [RFC PATCH 08/12] futex: Implement PING futex handoff Suleiman Souhlal
2026-09-17 4:33 ` [RFC PATCH 09/12] futex: Wake up donor in PING futex unlock Suleiman Souhlal
2026-09-17 4:33 ` [RFC PATCH 10/12] futex: Optimistic spinning for PING futexes Suleiman Souhlal
2026-09-17 4:33 ` [RFC PATCH 11/12] futex: Allow userspace stealing " Suleiman Souhlal
2026-09-17 4:33 ` [RFC PATCH 12/12] tools/testing/futex: Add ping_bench, a tool for benchmarking futexes Suleiman Souhlal
2026-09-17 8:58 ` Peter Zijlstra [this message]
2026-09-17 17:53 ` [RFC PATCH 00/12] FUTEX_PING: A stealable futex using Proxy Execution John Stultz
2026-09-17 18:51 ` Steven Rostedt
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