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Sat, 17 Jul 2021 09:31:00 +0000 (UTC) Received: from T590 (ovpn-12-83.pek2.redhat.com [10.72.12.83]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 6DC6360C0F; Sat, 17 Jul 2021 09:30:48 +0000 (UTC) Date: Sat, 17 Jul 2021 17:30:43 +0800 From: Ming Lei To: Bjorn Helgaas Cc: Jens Axboe , Christoph Hellwig , linux-block@vger.kernel.org, linux-nvme@lists.infradead.org, Greg Kroah-Hartman , Bjorn Helgaas , linux-pci@vger.kernel.org, Thomas Gleixner , Sagi Grimberg , Daniel Wagner , Wen Xiong , John Garry , Hannes Reinecke , Keith Busch Subject: Re: [PATCH V4 1/3] driver core: mark device as irq affinity managed if any irq is managed Message-ID: References: <20210715120844.636968-2-ming.lei@redhat.com> <20210716200154.GA2113453@bjorn-Precision-5520> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210716200154.GA2113453@bjorn-Precision-5520> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210717_023109_494464_76CD1957 X-CRM114-Status: GOOD ( 32.12 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On Fri, Jul 16, 2021 at 03:01:54PM -0500, Bjorn Helgaas wrote: > On Thu, Jul 15, 2021 at 08:08:42PM +0800, Ming Lei wrote: > > irq vector allocation with managed affinity may be used by driver, and > > blk-mq needs this info because managed irq will be shutdown when all > > CPUs in the affinity mask are offline. > > > > The info of using managed irq is often produced by drivers(pci subsystem, > > Add space between "drivers" and "(". > s/pci/PCI/ OK. > > Does this "managed IRQ" (or "managed affinity", not sure what the > correct terminology is here) have something to do with devm? > > > platform device, ...), and it is consumed by blk-mq, so different subsystems > > are involved in this info flow > > Add period at end of sentence. OK. > > > Address this issue by adding one field of .irq_affinity_managed into > > 'struct device'. > > > > Suggested-by: Christoph Hellwig > > Signed-off-by: Ming Lei > > --- > > drivers/base/platform.c | 7 +++++++ > > drivers/pci/msi.c | 3 +++ > > include/linux/device.h | 1 + > > 3 files changed, 11 insertions(+) > > > > diff --git a/drivers/base/platform.c b/drivers/base/platform.c > > index 8640578f45e9..d28cb91d5cf9 100644 > > --- a/drivers/base/platform.c > > +++ b/drivers/base/platform.c > > @@ -388,6 +388,13 @@ int devm_platform_get_irqs_affinity(struct platform_device *dev, > > ptr->irq[i], ret); > > goto err_free_desc; > > } > > + > > + /* > > + * mark the device as irq affinity managed if any irq affinity > > + * descriptor is managed > > + */ > > + if (desc[i].is_managed) > > + dev->dev.irq_affinity_managed = true; > > } > > > > devres_add(&dev->dev, ptr); > > diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c > > index 3d6db20d1b2b..7ddec90b711d 100644 > > --- a/drivers/pci/msi.c > > +++ b/drivers/pci/msi.c > > @@ -1197,6 +1197,7 @@ int pci_alloc_irq_vectors_affinity(struct pci_dev *dev, unsigned int min_vecs, > > if (flags & PCI_IRQ_AFFINITY) { > > if (!affd) > > affd = &msi_default_affd; > > + dev->dev.irq_affinity_managed = true; > > This is really opaque to me. I can't tell what the connection between > PCI_IRQ_AFFINITY and irq_affinity_managed is. Comment for PCI_IRQ_AFFINITY is 'Auto-assign affinity', 'irq_affinity_managed' basically means that irq's affinity is managed by kernel. What blk-mq needs is exactly if PCI_IRQ_AFFINITY is applied when allocating irq vectors. When PCI_IRQ_AFFINITY is used, genirq will shutdown the irq when all CPUs in the assigned affinity are offline, then blk-mq has to drain all in-flight IOs which will be completed via this irq and prevent new IO. That is the connection. Or you think 'irq_affinity_managed' isn't named well? > > AFAICT the only place irq_affinity_managed is ultimately used is > blk_mq_hctx_notify_offline(), and there's no obvious connection > between that and this code. I believe the connection is described in comment. Thanks, Ming _______________________________________________ Linux-nvme mailing list Linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme