From: Frederic Weisbecker <fweisbec@gmail.com>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Chris Metcalf <cmetcalf@mellanox.com>,
Thomas Gleixner <tglx@linutronix.de>,
"linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
Christoph Lameter <cl@linux.com>, Michal Hocko <mhocko@suse.com>,
Gilad Ben Yossef <giladb@mellanox.com>,
Andrew Morton <akpm@linux-foundation.org>,
Viresh Kumar <viresh.kumar@linaro.org>,
Linux API <linux-api@vger.kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Ingo Molnar <mingo@kernel.org>, Tejun Heo <tj@kernel.org>,
Rik van Riel <riel@redhat.com>, Will Deacon <will.deacon@arm.com>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH v15 04/13] task_isolation: add initial support
Date: Tue, 27 Sep 2016 16:22:20 +0200 [thread overview]
Message-ID: <20160927142219.GC6242@lerouge> (raw)
In-Reply-To: <CALCETrXrsZjMjdd1jACbrz8GMXQC5FmF8BbkHobmMCbG5GPN7w@mail.gmail.com>
On Fri, Sep 02, 2016 at 10:28:00AM -0700, Andy Lutomirski wrote:
>
> Unless I'm missing something (which is reasonably likely), couldn't
> the isolation code just force or require rcu_nocbs on the isolated
> CPUs to avoid this problem entirely.
rcu_nocb is already implied by nohz_full. Which means that RCU callbacks
are offlined outside the nohz_full set of CPUs.
>
> I admit I still don't understand why the RCU context tracking code
> can't just run the callback right away instead of waiting however many
> microseconds in general. I feel like paulmck has explained it to me
> at least once, but that doesn't mean I remember the answer.
The RCU context tracking doesn't take care of callbacks. It's only there
to tell the RCU core whether the CPU runs code that may or may not run
RCU read side critical sections. This is assumed by "kernel may use RCU,
userspace can't".
next prev parent reply other threads:[~2016-09-27 14:22 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-16 21:19 [PATCH v15 00/13] support "task_isolation" mode Chris Metcalf
2016-08-16 21:19 ` [PATCH v15 04/13] task_isolation: add initial support Chris Metcalf
2016-08-29 16:33 ` Peter Zijlstra
2016-08-29 16:40 ` Chris Metcalf
2016-08-29 16:48 ` Peter Zijlstra
2016-08-29 16:53 ` Chris Metcalf
2016-08-30 7:59 ` Peter Zijlstra
2016-08-30 7:58 ` Peter Zijlstra
[not found] ` <20160830075854.GZ10153-ndre7Fmf5hadTX5a5knrm8zTDFooKrT+cvkQGrU6aU0@public.gmane.org>
2016-08-30 15:32 ` Chris Metcalf
2016-08-30 16:30 ` Andy Lutomirski
2016-08-30 17:02 ` Chris Metcalf
2016-08-30 18:43 ` Andy Lutomirski
2016-08-30 19:37 ` Chris Metcalf
2016-08-30 19:50 ` Andy Lutomirski
2016-09-02 14:04 ` Chris Metcalf
[not found] ` <3f84f736-ed7f-adff-d5f0-4f7db664208f-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
2016-09-02 17:28 ` Andy Lutomirski
2016-09-09 17:40 ` Chris Metcalf
2016-09-12 17:41 ` Andy Lutomirski
2016-09-12 19:25 ` Chris Metcalf
2016-09-27 14:22 ` Frederic Weisbecker [this message]
2016-09-27 14:39 ` Peter Zijlstra
2016-09-27 14:51 ` Frederic Weisbecker
2016-09-27 14:48 ` Paul E. McKenney
2016-09-30 16:59 ` Chris Metcalf
2016-09-01 10:06 ` Peter Zijlstra
2016-09-02 14:03 ` Chris Metcalf
2016-09-02 16:40 ` Peter Zijlstra
2016-08-16 21:19 ` [PATCH v15 12/13] task_isolation: add user-settable notification signal Chris Metcalf
[not found] ` <1471382376-5443-1-git-send-email-cmetcalf-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
2016-08-17 19:37 ` [PATCH] Fix /proc/stat freezes (was [PATCH v15] "task_isolation" mode) Christoph Lameter
2016-08-20 1:42 ` Chris Metcalf
2016-09-28 13:16 ` Frederic Weisbecker
2016-08-29 16:27 ` Ping: [PATCH v15 00/13] support "task_isolation" mode Chris Metcalf
2016-09-07 21:11 ` Francis Giraldeau
[not found] ` <057a958c-4491-b449-ae59-7d331afc872d-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2016-09-07 21:39 ` Francis Giraldeau
2016-09-08 16:21 ` Francis Giraldeau
2016-09-12 16:01 ` Chris Metcalf
2016-09-12 16:14 ` Peter Zijlstra
2016-09-12 21:15 ` Rafael J. Wysocki
2016-09-13 0:05 ` Rafael J. Wysocki
2016-09-13 16:00 ` Francis Giraldeau
2016-09-13 0:20 ` Francis Giraldeau
[not found] ` <3e93004f-e1c5-f606-33fb-7cb44b99eb0a-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2016-09-13 16:12 ` Chris Metcalf
2016-09-27 14:49 ` Frederic Weisbecker
2016-09-27 14:35 ` Frederic Weisbecker
2016-09-30 17:07 ` Chris Metcalf
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