From: Keith Busch <kbusch@kernel.org>
To: Sagi Grimberg <sagi@grimberg.me>
Cc: bigeasy@linutronix.de, hch@lst.de, tglx@linutronix.de,
linux-nvme@lists.infradead.org, ming.lei@redhat.com
Subject: Re: [PATCHv3 2/4] nvme/pci: Complete commands from primary handler
Date: Wed, 11 Dec 2019 05:25:06 +0900 [thread overview]
Message-ID: <20191210202506.GA26810@redsun51.ssa.fujisawa.hgst.com> (raw)
In-Reply-To: <6d55a705-6a43-5b47-166c-5d2b458fd6a5@grimberg.me>
On Tue, Dec 10, 2019 at 12:00:07PM -0800, Sagi Grimberg wrote:
>
> > diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
> > index a0138e3ca0b9..e415fadf7331 100644
> > --- a/drivers/nvme/host/pci.c
> > +++ b/drivers/nvme/host/pci.c
> > @@ -1055,6 +1055,10 @@ static irqreturn_t nvme_irq_check(int irq, void *data)
> > if (!nvme_cqe_pending(nvmeq))
> > return IRQ_NONE;
> > + nvme_irq(irq, data);
> > + if (!nvme_cqe_pending(nvmeq))
> > + return IRQ_HANDLED;
> > +
>
> Question Keith,
>
> If I have say 24 (or more) devices with a queue mapped to a cpu, and we
> happen to just reap in the primary handler for all devices, all the time,
> are we safe from cpu lockup?
I can't readily test that scenario, but I'm skeptical a workload
can keep the primary handler running without ever seeing it return
IRQ_WAKE_THREAD. If that is really a problem, we can mitigate it by
limiting the number of CQEs the primary handler may process.
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next prev parent reply other threads:[~2019-12-10 20:25 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-09 17:56 [PATCHv3 0/4] nvme pci interrupt handling improvements Keith Busch
2019-12-09 17:56 ` [PATCHv3 1/4] nvme/pci: Disable interrupts for threaded handler Keith Busch
2019-12-10 15:12 ` Daniel Wagner
2019-12-10 15:28 ` Sebastian Andrzej Siewior
2019-12-10 15:54 ` Keith Busch
2019-12-10 16:44 ` Daniel Wagner
2019-12-10 16:57 ` Keith Busch
2019-12-10 17:11 ` Daniel Wagner
2019-12-12 9:09 ` Christoph Hellwig
2019-12-12 15:53 ` Keith Busch
2019-12-09 17:56 ` [PATCHv3 2/4] nvme/pci: Complete commands from primary handler Keith Busch
2019-12-10 20:00 ` Sagi Grimberg
2019-12-10 20:25 ` Keith Busch [this message]
2019-12-10 21:14 ` Sagi Grimberg
2019-12-11 17:35 ` Keith Busch
2019-12-12 0:40 ` Sagi Grimberg
2019-12-12 1:02 ` Keith Busch
2019-12-12 22:55 ` Ming Lei
2019-12-12 23:30 ` Keith Busch
2019-12-13 0:52 ` Ming Lei
2019-12-12 9:14 ` Christoph Hellwig
2019-12-09 17:56 ` [PATCHv3 3/4] nvme/pci: Remove use_threaded_interrupts Keith Busch
2019-12-12 9:14 ` Christoph Hellwig
2019-12-12 15:45 ` Keith Busch
2019-12-18 7:29 ` Ming Lei
2019-12-18 15:50 ` Keith Busch
2019-12-19 1:10 ` Ming Lei
2019-12-09 17:56 ` [PATCHv3 4/4] nvme/pci: Poll threaded completions Keith Busch
2019-12-10 17:43 ` Daniel Wagner
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