From: Frederic Weisbecker <frederic@kernel.org>
To: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Joel Fernandes <joel@joelfernandes.org>,
Uladzislau Rezki <urezki@gmail.com>,
"Zhuo, Qiuxu" <qiuxu.zhuo@intel.com>,
linux-kernel@vger.kernel.org,
Lai Jiangshan <jiangshanlai@gmail.com>,
linux-doc@vger.kernel.org, rcu@vger.kernel.org
Subject: Re: [PATCH RFC v2] rcu: Add a minimum time for marking boot as completed
Date: Tue, 28 Feb 2023 00:40:38 +0100 [thread overview]
Message-ID: <Y/0/dnmIk508sidK@lothringen> (raw)
In-Reply-To: <20230227230502.GJ2948950@paulmck-ThinkPad-P17-Gen-1>
On Mon, Feb 27, 2023 at 03:05:02PM -0800, Paul E. McKenney wrote:
> On Mon, Feb 27, 2023 at 02:10:30PM -0500, Joel Fernandes wrote:
>
> The combination of sysfs manipulated by userspace and a kernel failsafe
> makes sense to me. Especially if by default triggering the failsafe
> splats. That way, bugs where userspace fails to update the sysfs file
> get caught.
>
> The non-default silent-failsafe mode is also useful to allow some power
> savings in advance of userspace getting the sysfs updating in place.
> And of course the default splatting setup can be used in internal testing
> with the release software being more tolerant of userspace foibles.
I'm wondering, this is all about CONFIG_RCU_LAZY, right? Or does also expedited
GP turned off a bit early or late on boot matter for anybody in practice?
So shouldn't we disable lazy callbacks by default when CONFIG_RCU_LAZY=y and then
turn it on with "sysctl kernel.rcu.lazy=1" only whenever userspace feels ready
about it? We can still keep the current call to rcu_end_inkernel_boot().
And if suddenly disabling lazy by default is an ABI breakage we can still add
CONFIG_RCU_LAZY_DEFAULT_DISABLED.
next prev parent reply other threads:[~2023-02-27 23:40 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-25 3:34 [PATCH RFC v2] rcu: Add a minimum time for marking boot as completed Joel Fernandes (Google)
2023-02-25 3:36 ` Randy Dunlap
2023-02-26 19:45 ` Frederic Weisbecker
2023-02-26 23:07 ` Joel Fernandes
2023-02-27 7:53 ` Zhuo, Qiuxu
2023-02-27 13:22 ` Joel Fernandes
2023-02-27 14:55 ` Paul E. McKenney
2023-02-27 15:16 ` Joel Fernandes
2023-02-27 18:06 ` Uladzislau Rezki
2023-02-27 18:15 ` Joel Fernandes
2023-02-27 18:20 ` Uladzislau Rezki
2023-02-27 18:27 ` Joel Fernandes
2023-02-27 18:57 ` Uladzislau Rezki
2023-02-27 19:10 ` Joel Fernandes
2023-02-27 23:05 ` Paul E. McKenney
2023-02-27 23:24 ` Joel Fernandes
2023-02-27 23:40 ` Frederic Weisbecker [this message]
2023-02-28 1:30 ` Joel Fernandes
2023-02-28 11:04 ` Frederic Weisbecker
2023-02-28 20:09 ` Joel Fernandes
2023-03-01 17:11 ` Frederic Weisbecker
2023-03-01 21:31 ` Joel Fernandes
2023-03-02 0:49 ` Paul E. McKenney
2023-03-02 1:08 ` Joel Fernandes
2023-03-02 1:19 ` Paul E. McKenney
2023-02-28 11:42 ` Uladzislau Rezki
2023-02-28 6:40 ` Zhuo, Qiuxu
2023-02-28 14:27 ` Joel Fernandes
2023-03-01 1:34 ` Zhuo, Qiuxu
2023-03-01 15:57 ` Joel Fernandes
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