Messages in this thread | | | From | Andy Shevchenko <> | Date | Wed, 28 Feb 2018 17:59:54 +0200 | Subject | Re: [PATCH V2] nvme-pci: assign separate irq vectors for adminq and ioq0 |
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On Wed, Feb 28, 2018 at 5:48 PM, Jianchao Wang <jianchao.w.wang@oracle.com> wrote: > Currently, adminq and ioq0 share the same irq vector. This is > unfair for both amdinq and ioq0. > - For adminq, its completion irq has to be bound on cpu0. It > just has only one hw queue, it is unreasonable to do this. > - For ioq0, when the irq fires for io completion, the adminq irq > action on this irq vector will introduce an uncached access on > adminq cqe at least, even worse when adminq is busy. > > To improve this, allocate separate irq vectors for adminq and > ioq0, and not set irq affinity for adminq one. If just one irq > vector, setup adminq + 1 ioq and let them share it. In addition > add new helper interface nvme_ioq_vector to get ioq vector.
> +static inline unsigned int nvme_ioq_vector(struct nvme_dev *dev, > + unsigned int qid) > +{ > + /* > + * If controller has only legacy or single-message MSI, there will > + * be only 1 irq vector. At the moment, we setup adminq + 1 ioq > + * and let them share irq vector. > + */ > + return (dev->num_vecs == 1) ? 0 : qid;
Redundant parens.
> +}
> > for (i = dev->ctrl.queue_count; i <= dev->max_qid; i++) { > - /* vector == qid - 1, match nvme_create_queue */
> if (nvme_alloc_queue(dev, i, dev->q_depth, > - pci_irq_get_node(to_pci_dev(dev->dev), i - 1))) { > + pci_irq_get_node(to_pci_dev(dev->dev), > + nvme_ioq_vector(dev, i)))) {
Perhaps better to introduce a temporary variable to make it readable?
> ret = -ENOMEM; > break; > }
> + ret = pci_alloc_irq_vectors_affinity(pdev, 1, (nr_io_queues + 1), > + PCI_IRQ_ALL_TYPES | PCI_IRQ_AFFINITY, &affd); > + if (ret <= 0) > return -EIO; > - dev->max_qid = nr_io_queues; > - > + dev->num_vecs = ret; > + dev->max_qid = (ret > 1) ? (ret - 1) : 1;
I don not see how ret can possible be < 1 here.
Thus, the logic looks like this: if ret >= 2 => return ret - 1; // Possible variants [1..ret - 1] if ret == 1 => return 1;
So, for ret == 1 or ret == 2 we still use 1.
Is it by design?
Can it be written like
dev->max_qid = max(ret - 1, 1);
-- With Best Regards, Andy Shevchenko
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