From: Peter Zijlstra <peterz@infradead.org>
To: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Joel Fernandes <joel@joelfernandes.org>,
Frederic Weisbecker <fweisbec@gmail.com>,
Thomas Gleixner <tglx@linutronix.de>,
linux-kernel@vger.kernel.org, Boqun Feng <boqun.feng@gmail.com>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>
Subject: Re: RCU vs NOHZ
Date: Thu, 29 Sep 2022 21:08:42 +0200 [thread overview]
Message-ID: <YzXtOi7rjjWI0ea0@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20220929163624.GN4196@paulmck-ThinkPad-P17-Gen-1>
On Thu, Sep 29, 2022 at 09:36:24AM -0700, Paul E. McKenney wrote:
> > How has this been tried; and why did the energy cost go up? Is this
> > because the offload thread ends up waking up the CPU we just put to
> > sleep?
>
> Because doing the additional work consumes energy. I am not clear on
> exactly what you are asking for here, given the limitations of the tools
> that measure energy consumption.
What additional work? Splicing the cpu pending list onto another list
with or without atomic op barely qualifies for work. The main point is
making sure the pending list isn't in the way of going (deep) idle.
next prev parent reply other threads:[~2022-09-29 19:08 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-15 8:39 Peter Zijlstra
2022-09-15 15:37 ` Joel Fernandes
2022-09-15 16:06 ` Paul E. McKenney
2022-09-15 18:50 ` Peter Zijlstra
2022-09-15 19:14 ` Paul E. McKenney
2022-09-15 22:30 ` Peter Zijlstra
2022-09-16 3:40 ` Joel Fernandes
2022-09-16 7:58 ` Paul E. McKenney
2022-09-16 9:20 ` Peter Zijlstra
2022-09-16 18:11 ` Joel Fernandes
2022-09-17 13:35 ` Peter Zijlstra
2022-09-17 13:52 ` Joel Fernandes
2022-09-17 14:28 ` Paul E. McKenney
2022-09-17 14:25 ` Paul E. McKenney
2022-09-21 21:36 ` Paul E. McKenney
2022-09-23 15:12 ` Joel Fernandes
2022-09-23 16:01 ` Paul E. McKenney
2022-09-23 17:47 ` Joel Fernandes
2022-09-23 18:15 ` Paul E. McKenney
2022-09-29 11:06 ` Peter Zijlstra
2022-09-29 10:55 ` Peter Zijlstra
2022-09-29 15:20 ` Paul E. McKenney
2022-09-29 15:46 ` Paul E. McKenney
2022-09-29 16:05 ` Joel Fernandes
2022-09-29 16:23 ` Peter Zijlstra
2022-09-29 16:42 ` Paul E. McKenney
2022-09-29 19:01 ` Peter Zijlstra
2022-09-29 19:52 ` Paul E. McKenney
2022-09-29 16:18 ` Peter Zijlstra
2022-09-29 16:36 ` Paul E. McKenney
2022-09-29 19:08 ` Peter Zijlstra [this message]
2022-09-29 19:56 ` Paul E. McKenney
2022-09-30 14:48 ` Paul E. McKenney
2022-09-23 19:47 Joel Fernandes
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