From: Keith Busch <kbusch@kernel.org>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: ming.lei@redhat.com, helgaas@kernel.org, hch@lst.de,
linux-nvme@lists.infradead.org, sagi@grimberg.me
Subject: Re: [PATCH 0/4] nvme: Threaded interrupt handling improvements
Date: Fri, 29 Nov 2019 09:27:19 -0700 [thread overview]
Message-ID: <20191129162719.GA47681@C02WT3WMHTD6.lpcnextlight.net> (raw)
In-Reply-To: <20191129094640.6fq6wcxmfi4fwnlw@linutronix.de>
On Fri, Nov 29, 2019 at 10:46:40AM +0100, Sebastian Andrzej Siewior wrote:
> On 2019-11-28 02:58:20 [+0900], Keith Busch wrote:
> > Threaded interrupts allow the device to continue sending interrupt
> > messages while the driver is handling the previous notification. This
> > can cause a significant amount of CPU cycles unnecessarily spent in hard
> > irq context, and potentially triggers spurious interrupt detection to
> > disable the nvme interrupt.
>
> Thank you for looking into this.
> To be clear: the "spurious interrupt detector" won't do a thing if you
> never return IRQ_NONE. As long as you return IRQ_HANDLED, everything is
> fine.
That's not entirely accurate. We have to return IRQ_WAKE_THREAD
from the hardirq handler, which gets converted to IRQ_NONE if
desc->threads_handled hasn't changed and considered spurious. If
the threaded handler runs sufficiently long, desc->threads_handled
won't get updated frequently enough, so this series fixes that for
nvme by masking the interrupt in the device, preventing future hard
irq callbacks.
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next prev parent reply other threads:[~2019-11-29 16:27 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-27 17:58 [PATCH 0/4] nvme: Threaded interrupt handling improvements Keith Busch
2019-11-27 17:58 ` [PATCH 1/4] PCI/MSI: Export __pci_msix_desc_mask_irq Keith Busch
2019-11-28 2:42 ` Sagi Grimberg
2019-11-28 3:41 ` Keith Busch
2019-11-28 7:17 ` Christoph Hellwig
2019-11-27 17:58 ` [PATCH 2/4] nvme/pci: Mask legacy and MSI in threaded handler Keith Busch
2019-11-28 3:39 ` Ming Lei
2019-11-28 3:48 ` Keith Busch
2019-11-28 3:58 ` Ming Lei
2019-11-28 4:14 ` Keith Busch
2019-11-28 8:41 ` Ming Lei
2019-11-27 17:58 ` [PATCH 3/4] nvme/pci: Mask MSIx interrupts for threaded handling Keith Busch
2019-11-28 7:19 ` Christoph Hellwig
2019-11-27 17:58 ` [PATCH 4/4] nvme/pci: Spin threaded interrupt completions Keith Busch
2019-11-28 2:46 ` Sagi Grimberg
2019-11-28 3:28 ` Keith Busch
2019-11-28 3:51 ` Ming Lei
2019-11-28 3:58 ` Keith Busch
2019-11-28 7:22 ` Christoph Hellwig
2019-11-29 9:13 ` Sebastian Andrzej Siewior
2019-11-30 18:10 ` Keith Busch
2019-12-02 1:10 ` Ming Lei
2019-12-02 1:30 ` Keith Busch
2019-12-02 16:51 ` Sebastian Andrzej Siewior
2019-11-28 7:50 ` [PATCH 0/4] nvme: Threaded interrupt handling improvements Christoph Hellwig
2019-11-28 17:59 ` Keith Busch
2019-11-29 8:30 ` Christoph Hellwig
2019-11-29 9:46 ` Sebastian Andrzej Siewior
2019-11-29 16:27 ` Keith Busch [this message]
2019-11-29 17:05 ` Sebastian Andrzej Siewior
2019-11-30 17:02 ` Keith Busch
2019-12-02 17:05 ` Sebastian Andrzej Siewior
2019-12-02 17:12 ` Christoph Hellwig
2019-12-02 18:06 ` Keith Busch
2019-12-03 7:40 ` Christoph Hellwig
2019-12-02 19:57 ` Sebastian Andrzej Siewior
2019-12-03 7:42 ` Christoph Hellwig
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