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NVMe: Restructure MSI / MSI-X setup

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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: Matthew Wilcox <matthew.r.wilcox@intel.com>
This commit is contained in:
Matthew Wilcox 2013-06-20 10:53:48 -04:00
parent 03ea83e9a3
commit 063a8096f3
1 changed files with 30 additions and 28 deletions
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58
drivers/block/nvme-core.c
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@ -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]);
@ -1659,38 +1658,41 @@ 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 (result < 0) {
vecs = nr_io_queues;
if (vecs > 32)
vecs = 32;
for (;;) {
result = pci_enable_msi_block(pdev, vecs);
if (result == 0) {
for (i = 0; i < vecs; i++)
dev->entry[i].vector = i + pdev->irq;
break;
} else if (result < 0) {
vecs = 1;
break;
}
vecs = result;
}
}
if (nr_io_queues == 0) {
nr_io_queues = q_count;
for (;;) {
result = pci_enable_msi_block(pdev, nr_io_queues);
if (result == 0) {
for (i = 0; i < nr_io_queues; i++)
dev->entry[i].vector = i + pdev->irq;
break;
} else if (result > 0) {
nr_io_queues = result;
continue;
} else {
nr_io_queues = 1;
break;
}
}
}
/*
* 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 */