Commit 063a8096 authored by Matthew Wilcox's avatar Matthew Wilcox
Browse files

NVMe: Restructure MSI / MSI-X setup 



The current code copies 'nr_io_queues' into 'q_count', modifies
'nr_io_queues' during MSI-X setup, then resets 'nr_io_queues' for
MSI setup.  Instead, copy 'nr_io_queues' into 'vecs' and modify 'vecs'
during both MSI-X and MSI setup.

This lets us simplify the for-loops that set up MSI-X and MSI, and opens
the possibility of using more I/O queues than we have interrupt vectors,
should future benchmarking prove that to be a useful feature.

Signed-off-by: default avatarMatthew Wilcox <matthew.r.wilcox@intel.com>
parent 03ea83e9

drivers/block/nvme-core.c

+23 −21
Original line number Diff line number Diff line
@@ -1638,7 +1638,7 @@ static int set_queue_count(struct nvme_dev *dev, int count) 
static int nvme_setup_io_queues(struct nvme_dev *dev)

{

	struct pci_dev *pdev = dev->pci_dev;

	int result, cpu, i, nr_io_queues, db_bar_size, q_depth, q_count;

	int result, cpu, i, vecs, nr_io_queues, db_bar_size, q_depth;



	nr_io_queues = num_online_cpus();

	result = set_queue_count(dev, nr_io_queues);
@@ -1647,7 +1647,6 @@ static int nvme_setup_io_queues(struct nvme_dev *dev) 
	if (result < nr_io_queues)

		nr_io_queues = result;



	q_count = nr_io_queues;

	/* Deregister the admin queue's interrupt */

	free_irq(dev->entry[0].vector, dev->queues[0]);
@@ -1659,39 +1658,42 @@ static int nvme_setup_io_queues(struct nvme_dev *dev) 
		dev->queues[0]->q_db = dev->dbs;

	}



	for (i = 0; i < nr_io_queues; i++)

	vecs = nr_io_queues;

	for (i = 0; i < vecs; i++)

		dev->entry[i].entry = i;

	for (;;) {

		result = pci_enable_msix(pdev, dev->entry, nr_io_queues);

		if (result == 0) {

			break;

		} else if (result > 0) {

			nr_io_queues = result;

			continue;

		} else {

			nr_io_queues = 0;

		result = pci_enable_msix(pdev, dev->entry, vecs);

		if (result <= 0)

			break;

		}

		vecs = result;

	}



	if (nr_io_queues == 0) {

		nr_io_queues = q_count;

	if (result < 0) {

		vecs = nr_io_queues;

		if (vecs > 32)

			vecs = 32;

		for (;;) {

			result = pci_enable_msi_block(pdev, nr_io_queues);

			result = pci_enable_msi_block(pdev, vecs);

			if (result == 0) {

				for (i = 0; i < nr_io_queues; i++)

				for (i = 0; i < vecs; i++)

					dev->entry[i].vector = i + pdev->irq;

				break;

			} else if (result > 0) {

				nr_io_queues = result;

				continue;

			} else {

				nr_io_queues = 1;

			} else if (result < 0) {

				vecs = 1;

				break;

			}

			vecs = result;

		}

	}



	/*

	 * Should investigate if there's a performance win from allocating

	 * more queues than interrupt vectors; it might allow the submission

	 * path to scale better, even if the receive path is limited by the

	 * number of interrupts.

	 */

	nr_io_queues = vecs;



	result = queue_request_irq(dev, dev->queues[0], "nvme admin");

	/* XXX: handle failure here */

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