From: Keith Busch <kbusch@kernel.org>
To: Ming Lei <ming.lei@redhat.com>
Cc: Jens Axboe <axboe@fb.com>, Hannes Reinecke <hare@suse.com>,
John Garry <john.garry@huawei.com>,
Bart Van Assche <bvanassche@acm.org>,
linux-scsi@vger.kernel.org, Peter Zijlstra <peterz@infradead.org>,
Long Li <longli@microsoft.com>,
Daniel Lezcano <daniel.lezcano@linaro.org>,
LKML <linux-kernel@vger.kernel.org>,
linux-nvme@lists.infradead.org,
Keith Busch <keith.busch@intel.com>,
Ingo Molnar <mingo@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
Christoph Hellwig <hch@lst.de>, Sagi Grimberg <sagi@grimberg.me>
Subject: Re: [PATCH 1/4] softirq: implement IRQ flood detection mechanism
Date: Fri, 6 Sep 2019 08:18:58 -0600 [thread overview]
Message-ID: <20190906141858.GA3953@localhost.localdomain> (raw)
In-Reply-To: <20190906014819.GB27116@ming.t460p>
On Fri, Sep 06, 2019 at 09:48:21AM +0800, Ming Lei wrote:
> When one IRQ flood happens on one CPU:
>
> 1) softirq handling on this CPU can't make progress
>
> 2) kernel thread bound to this CPU can't make progress
>
> For example, network may require softirq to xmit packets, or another irq
> thread for handling keyboards/mice or whatever, or rcu_sched may depend
> on that CPU for making progress, then the irq flood stalls the whole
> system.
>
> >
> > AFAIU, there are fast medium where the responses to requests are faster
> > than the time to process them, right?
>
> Usually medium may not be faster than CPU, now we are talking about
> interrupts, which can be originated from lots of devices concurrently,
> for example, in Long Li'test, there are 8 NVMe drives involved.
Why are all 8 nvmes sharing the same CPU for interrupt handling?
Shouldn't matrix_find_best_cpu_managed() handle selecting the least used
CPU from the cpumask for the effective interrupt handling?
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next prev parent reply other threads:[~2019-09-06 14:28 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20190827085344.30799-1-ming.lei@redhat.com>
[not found] ` <20190827085344.30799-2-ming.lei@redhat.com>
[not found] ` <alpine.DEB.2.21.1908271633450.1939@nanos.tec.linutronix.de>
[not found] ` <20190827225827.GA5263@ming.t460p>
[not found] ` <alpine.DEB.2.21.1908280104330.1939@nanos.tec.linutronix.de>
[not found] ` <20190828110633.GC15524@ming.t460p>
[not found] ` <alpine.DEB.2.21.1908281316230.1869@nanos.tec.linutronix.de>
[not found] ` <20190828135054.GA23861@ming.t460p>
[not found] ` <alpine.DEB.2.21.1908281605190.23149@nanos.tec.linutronix.de>
2019-09-03 3:30 ` [PATCH 1/4] softirq: implement IRQ flood detection mechanism Ming Lei
2019-09-03 5:59 ` Daniel Lezcano
2019-09-03 6:31 ` Ming Lei
2019-09-03 6:40 ` Daniel Lezcano
2019-09-03 7:28 ` Ming Lei
2019-09-03 7:50 ` Daniel Lezcano
2019-09-03 9:30 ` Ming Lei
2019-09-04 17:07 ` Bart Van Assche
2019-09-04 17:31 ` Daniel Lezcano
2019-09-04 17:38 ` Bart Van Assche
2019-09-04 18:02 ` Peter Zijlstra
2019-09-04 19:47 ` Bart Van Assche
2019-09-05 9:11 ` Ming Lei
2019-09-05 9:06 ` Ming Lei
2019-09-05 10:37 ` Daniel Lezcano
2019-09-06 1:22 ` Long Li
2019-09-06 4:36 ` Daniel Lezcano
2019-09-06 4:44 ` Long Li
2019-09-06 1:48 ` Ming Lei
2019-09-06 5:14 ` Daniel Lezcano
2019-09-06 18:30 ` Sagi Grimberg
2019-09-06 18:52 ` Keith Busch
2019-09-07 0:01 ` Ming Lei
2019-09-10 3:10 ` Sagi Grimberg
2019-09-18 0:00 ` Long Li
2019-09-20 17:14 ` Sagi Grimberg
2019-09-20 19:12 ` Long Li
2019-09-20 20:45 ` Sagi Grimberg
2019-09-24 0:57 ` Long Li
2019-09-18 14:37 ` Ming Lei
2019-09-20 17:09 ` Sagi Grimberg
2019-09-06 14:18 ` Keith Busch [this message]
2019-09-06 17:50 ` Long Li
2019-09-06 22:19 ` Ming Lei
2019-09-06 22:25 ` Keith Busch
2019-09-06 23:13 ` Ming Lei
2019-09-10 0:24 ` Ming Lei
2019-09-03 8:09 ` Thomas Gleixner
2019-09-03 9:24 ` Ming Lei
[not found] ` <20190827085344.30799-5-ming.lei@redhat.com>
2019-09-06 8:50 ` [PATCH 4/4] genirq: use irq's affinity for threaded irq with IRQF_RESCUE_THREAD John Garry
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