From: Peter Zijlstra <peterz@infradead.org>
To: Stephen Warren <swarren@wwwdotorg.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>,
LKML <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Eric Dumazet <eric.dumazet@gmail.com>,
Ingo Molnar <mingo@kernel.org>, Kevin Hilman <khilman@linaro.org>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Thomas Gleixner <tglx@linutronix.de>,
Viresh Kumar <viresh.kumar@linaro.org>,
"Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>,
"linux-next@vger.kernel.org" <linux-next@vger.kernel.org>
Subject: Re: [PATCH 2/6] irq_work: Implement remote queueing
Date: Wed, 25 Jun 2014 07:12:34 +0200 [thread overview]
Message-ID: <20140625051234.GD6758@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <53A9E0A5.5040402@wwwdotorg.org>
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On Tue, Jun 24, 2014 at 02:33:41PM -0600, Stephen Warren wrote:
> On 06/10/2014 09:15 AM, Frederic Weisbecker wrote:
> > irq work currently only supports local callbacks. However its code
> > is mostly ready to run remote callbacks and we have some potential user.
> >
> > The full nohz subsystem currently open codes its own remote irq work
> > on top of the scheduler ipi when it wants a CPU to reevaluate its next
> > tick. However this ad hoc solution bloats the scheduler IPI.
> >
> > Lets just extend the irq work subsystem to support remote queuing on top
> > of the generic SMP IPI to handle this kind of user. This shouldn't add
> > noticeable overhead.
>
> I'm running next-20140624 on an ARM system, and this patch causes CPU
> hot(un)plug to Oops for me; the following fires:
>
> void irq_work_run(void)
> {
> BUG_ON(!in_irq());
>
> I found that Linus's master (8b8f5d971584 "Merge tag 'compress-3.16-rc3'
> of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core")
> works fine. I found that this commit inside the tip(?) tree works fine
> (478850160636 "irq_work: Implement remote queueing"). However, if I
> merge the two together, I hit that BUG_ON.
>
> I think the issue is:
>
> This commit adds a call from
> generic_smp_call_function_single_interrupt() to irq_work_run().
>
> Srivatsa's patch adds a call from hotplug_cfd() to
> flush_smp_call_function_queue() to, which I imagine happens in
> non-interrupt context. Note that this patch moves most of the body of
> generic_smp_call_function_single_interrupt() into
> flush_smp_call_function_queue().
Right you are.. I think I'll just remove the BUG_ON(), Frederic?
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next prev parent reply other threads:[~2014-06-25 5:12 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-10 15:15 [PATCH 0/6] nohz: Move nohz kick out of scheduler IPI, v8 Frederic Weisbecker
2014-06-10 15:15 ` [PATCH 1/6] irq_work: Split raised and lazy lists Frederic Weisbecker
2014-06-10 15:15 ` [PATCH 2/6] irq_work: Implement remote queueing Frederic Weisbecker
2014-06-24 20:33 ` Stephen Warren
2014-06-24 20:35 ` Stephen Warren
2014-06-25 5:12 ` Peter Zijlstra [this message]
2014-06-25 5:17 ` Peter Zijlstra
2014-06-25 6:37 ` Srivatsa S. Bhat
2014-06-25 9:36 ` Peter Zijlstra
2014-06-25 9:39 ` Peter Zijlstra
2014-06-25 9:50 ` Srivatsa S. Bhat
2014-06-25 9:54 ` Srivatsa S. Bhat
2014-06-25 10:19 ` Peter Zijlstra
2014-06-25 10:57 ` Srivatsa S. Bhat
2014-06-25 16:23 ` Stephen Warren
2014-06-25 16:38 ` Peter Zijlstra
2014-06-25 16:57 ` Srivatsa S. Bhat
2014-06-28 18:19 ` Borislav Petkov
2014-07-03 14:52 ` Frederic Weisbecker
2014-07-04 5:10 ` Sachin Kamat
2014-07-01 19:13 ` Stephen Warren
2014-06-10 15:15 ` [PATCH 3/6] nohz: Support nohz full remote kick Frederic Weisbecker
2014-06-10 15:15 ` [PATCH 4/6] nohz: Switch to nohz full remote kick on timer enqueue Frederic Weisbecker
2014-06-10 15:15 ` [PATCH 5/6] nohz: Use nohz own full kick on 2nd task enqueue Frederic Weisbecker
2014-06-10 15:15 ` [PATCH 6/6] nohz: Use IPI implicit full barrier against rq->nr_running r/w Frederic Weisbecker
2014-06-10 15:48 ` Peter Zijlstra
2014-06-10 16:24 ` Frederic Weisbecker
2014-06-10 15:48 ` [PATCH 0/6] nohz: Move nohz kick out of scheduler IPI, v8 Peter Zijlstra
2014-06-10 16:18 ` Frederic Weisbecker
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