[PATCH V3 4/5] nvme-pci: avoid irq allocation retrying via .calc_sets

Ming Lei
2019-02-13T10:51:21Z

Currently pre-caculate each set vectors, and this way requires same
'max_vecs' and 'min_vecs' passed to pci_alloc_irq_vectors_affinity(),
then nvme_setup_irqs() has to retry in case of allocation failure.

This usage & interface is a bit awkward because the retry should have
been avoided by providing one reasonable 'min_vecs'.

Implement the callback of .calc_sets, so that pci_alloc_irq_vectors_affinity()
can calculate each set's vector after IRQ vectors is allocated and
before spread IRQ, then NVMe's retry in case of irq allocation failure
can be removed.

Reviewed-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
drivers/nvme/host/pci.c | 62 +++++++++++++------------------------------------
1 file changed, 16 insertions(+), 46 deletions(-)

diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 0086bdf80ea1..8c51252a897e 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -2078,14 +2078,25 @@ static void nvme_calc_io_queues(struct nvme_dev *dev, unsigned int irq_queues)
}
}

+static void nvme_calc_irq_sets(struct irq_affinity *affd, int nvecs)
+{
+ struct nvme_dev *dev = affd->priv;
+
+ nvme_calc_io_queues(dev, nvecs);
+
+ affd->set_vectors[HCTX_TYPE_DEFAULT] = dev->io_queues[HCTX_TYPE_DEFAULT];
+ affd->set_vectors[HCTX_TYPE_READ] = dev->io_queues[HCTX_TYPE_READ];
+ affd->nr_sets = 2;
+}
+
static int nvme_setup_irqs(struct nvme_dev *dev, unsigned int nr_io_queues)
{
struct pci_dev *pdev = to_pci_dev(dev->dev);
struct irq_affinity affd = {
.pre_vectors = 1,
- .nr_sets = 2,
+ .calc_sets = nvme_calc_irq_sets,
+ .priv = dev,
};
- int *irq_sets = affd.set_vectors;
int result = 0;
unsigned int irq_queues, this_p_queues;

@@ -2102,50 +2113,8 @@ static int nvme_setup_irqs(struct nvme_dev *dev, unsigned int nr_io_queues)
}
dev->io_queues[HCTX_TYPE_POLL] = this_p_queues;

- /*
- * For irq sets, we have to ask for minvec == maxvec. This passes
- * any reduction back to us, so we can adjust our queue counts and
- * IRQ vector needs.
- */
- do {
- nvme_calc_io_queues(dev, irq_queues);
- irq_sets[0] = dev->io_queues[HCTX_TYPE_DEFAULT];
- irq_sets[1] = dev->io_queues[HCTX_TYPE_READ];
- if (!irq_sets[1])
- affd.nr_sets = 1;
-
- /*
- * If we got a failure and we're down to asking for just
- * 1 + 1 queues, just ask for a single vector. We'll share
- * that between the single IO queue and the admin queue.
- * Otherwise, we assign one independent vector to admin queue.
- */
- if (irq_queues > 1)
- irq_queues = irq_sets[0] + irq_sets[1] + 1;
-
- result = pci_alloc_irq_vectors_affinity(pdev, irq_queues,
- irq_queues,
- PCI_IRQ_ALL_TYPES | PCI_IRQ_AFFINITY, &affd);
-
- /*
- * Need to reduce our vec counts. If we get ENOSPC, the
- * platform should support mulitple vecs, we just need
- * to decrease our ask. If we get EINVAL, the platform
- * likely does not. Back down to ask for just one vector.
- */
- if (result == -ENOSPC) {
- irq_queues--;
- if (!irq_queues)
- return result;
- continue;
- } else if (result == -EINVAL) {
- irq_queues = 1;
- continue;
- } else if (result <= 0)
- return -EIO;
- break;
- } while (1);
-
+ result = pci_alloc_irq_vectors_affinity(pdev, 1, irq_queues,
+ PCI_IRQ_ALL_TYPES | PCI_IRQ_AFFINITY, &affd);
return result;
}

@@ -3021,6 +2990,7 @@ static struct pci_driver nvme_driver = {

static int __init nvme_init(void)
{
+ BUILD_BUG_ON(2 > IRQ_MAX_SETS);
return pci_register_driver(&nvme_driver);
}

--
2.9.5