On Wed, Feb 28, 2018 at 5:48 PM, Jianchao Wang
<jianchao.w.w...@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
