From: Steven Rostedt <rostedt@goodmis.org>
To: Boqun Feng <boqun.feng@gmail.com>
Cc: rcu@vger.kernel.org, "Paul E. McKenney" <paulmck@kernel.org>,
Frederic Weisbecker <frederic@kernel.org>,
Neeraj Upadhyay <neeraj.upadhyay@kernel.org>,
Joel Fernandes <joel@joelfernandes.org>,
Josh Triplett <josh@joshtriplett.org>,
Uladzislau Rezki <urezki@gmail.com>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Lai Jiangshan <jiangshanlai@gmail.com>,
Zqiang <qiang.zhang1211@gmail.com>,
Davidlohr Bueso <dave@stgolabs.net>,
Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Juri Lelli <juri.lelli@redhat.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
Valentin Schneider <vschneid@redhat.com>,
Masami Hiramatsu <mhiramat@kernel.org>,
Shuah Khan <shuah@kernel.org>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Clark Williams <clrkwllms@kernel.org>,
linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org,
linux-kselftest@vger.kernel.org, linux-rt-devel@lists.linux.dev,
Ankur Arora <ankur.a.arora@oracle.com>
Subject: Re: [PATCH rcu 06/11] osnoise: provide quiescent states
Date: Tue, 4 Mar 2025 14:21:27 -0500 [thread overview]
Message-ID: <20250304142127.391ca6bd@gandalf.local.home> (raw)
In-Reply-To: <20250225035516.26443-7-boqun.feng@gmail.com>
On Mon, 24 Feb 2025 19:55:11 -0800
Boqun Feng <boqun.feng@gmail.com> wrote:
> From: Ankur Arora <ankur.a.arora@oracle.com>
>
> To reduce RCU noise for nohz_full configurations, osnoise depends
> on cond_resched() providing quiescent states for PREEMPT_RCU=n
> configurations. For PREEMPT_RCU=y configurations -- where
> cond_resched() is a stub -- we do this by directly calling
> rcu_momentary_eqs().
>
> With (PREEMPT_LAZY=y, PREEMPT_DYNAMIC=n), however, we have a
> configuration with (PREEMPTION=y, PREEMPT_RCU=n) where neither
> of the above can help.
>
> Handle that by providing an explicit quiescent state here for all
> configurations.
>
> As mentioned above this is not needed for non-stubbed cond_resched(),
> but, providing a quiescent state here just pulls in one that a future
> cond_resched() would provide, so doesn't cause any extra work for
> this configuration.
>
> Cc: Paul E. McKenney <paulmck@kernel.org>
> Cc: Daniel Bristot de Oliveira <bristot@kernel.org>
> Cc: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
-- Steve
> Suggested-by: Paul E. McKenney <paulmck@kernel.org>
> Acked-by: Daniel Bristot de Oliveira <bristot@kernel.org>
> Signed-off-by: Ankur Arora <ankur.a.arora@oracle.com>
> Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
> Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
> ---
next prev parent reply other threads:[~2025-03-04 19:20 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-02-25 3:55 [PATCH rcu 00/11] Lazy Preempt changes for v6.15 Boqun Feng
2025-02-25 3:55 ` [PATCH rcu 01/11] rcu: fix header guard for rcu_all_qs() Boqun Feng
2025-02-25 3:55 ` [PATCH rcu 02/11] rcu: rename PREEMPT_AUTO to PREEMPT_LAZY Boqun Feng
2025-02-25 3:55 ` [PATCH rcu 03/11] sched: update __cond_resched comment about RCU quiescent states Boqun Feng
2025-02-25 3:55 ` [PATCH rcu 04/11] rcu: handle unstable rdp in rcu_read_unlock_strict() Boqun Feng
2025-02-25 3:55 ` [PATCH rcu 05/11] rcu: handle quiescent states for PREEMPT_RCU=n, PREEMPT_COUNT=y Boqun Feng
2025-02-25 3:55 ` [PATCH rcu 06/11] osnoise: provide quiescent states Boqun Feng
2025-03-04 19:21 ` Steven Rostedt [this message]
2025-03-05 2:54 ` Boqun Feng
2025-02-25 3:55 ` [PATCH rcu 07/11] rcutorture: Update rcutorture_one_extend_check() for lazy preemption Boqun Feng
2025-02-25 3:55 ` [PATCH rcu 08/11] rcutorture: Update ->extendables check " Boqun Feng
2025-02-25 3:55 ` [PATCH rcu 09/11] rcu: limit PREEMPT_RCU configurations Boqun Feng
2025-02-25 3:55 ` [PATCH rcu 10/11] rcutorture: Make scenario TREE10 build CONFIG_PREEMPT_LAZY=y Boqun Feng
2025-02-25 3:55 ` [PATCH rcu 11/11] rcutorture: Make scenario TREE07 " Boqun Feng
2025-02-27 23:33 ` [PATCH rcu 00/11] Lazy Preempt changes for v6.15 Ankur Arora
2025-02-27 23:47 ` Paul E. McKenney
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20250304142127.391ca6bd@gandalf.local.home \
--to=rostedt@goodmis.org \
--cc=ankur.a.arora@oracle.com \
--cc=bigeasy@linutronix.de \
--cc=boqun.feng@gmail.com \
--cc=bsegall@google.com \
--cc=clrkwllms@kernel.org \
--cc=dave@stgolabs.net \
--cc=dietmar.eggemann@arm.com \
--cc=frederic@kernel.org \
--cc=jiangshanlai@gmail.com \
--cc=joel@joelfernandes.org \
--cc=josh@joshtriplett.org \
--cc=juri.lelli@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-kselftest@vger.kernel.org \
--cc=linux-rt-devel@lists.linux.dev \
--cc=linux-trace-kernel@vger.kernel.org \
--cc=mathieu.desnoyers@efficios.com \
--cc=mgorman@suse.de \
--cc=mhiramat@kernel.org \
--cc=mingo@redhat.com \
--cc=neeraj.upadhyay@kernel.org \
--cc=paulmck@kernel.org \
--cc=peterz@infradead.org \
--cc=qiang.zhang1211@gmail.com \
--cc=rcu@vger.kernel.org \
--cc=shuah@kernel.org \
--cc=urezki@gmail.com \
--cc=vincent.guittot@linaro.org \
--cc=vschneid@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
all inboxes | Powered by JetHome®