On Tue, Jun 14, 2016 at 09:59:01PM +0200, Christoph Hellwig wrote:
> Set the affinity_mask before allocating vectors.
>
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
> ---
> drivers/pci/msi.c | 26 ++++++++++++++++++++++++--
> include/linux/pci.h | 1 +
> 2 files changed, 25 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
> index a33adec..50d694c 100644
> --- a/drivers/pci/msi.c
> +++ b/drivers/pci/msi.c
> @@ -568,6 +568,7 @@ static struct msi_desc *msi_setup_entry(struct pci_dev *dev, int nvec)
> entry->msi_attrib.multi_cap = (control & PCI_MSI_FLAGS_QMASK) >> 1;
> entry->msi_attrib.multiple = ilog2(__roundup_pow_of_two(nvec));
> entry->nvec_used = nvec;
> + entry->affinity = dev->irq_affinity;
>
> if (control & PCI_MSI_FLAGS_64BIT)
> entry->mask_pos = dev->msi_cap + PCI_MSI_MASK_64;
> @@ -679,10 +680,18 @@ static void __iomem *msix_map_region(struct pci_dev *dev, unsigned nr_entries)
> static int msix_setup_entries(struct pci_dev *dev, void __iomem *base,
> struct msix_entry *entries, int nvec)
> {
> + const struct cpumask *mask = NULL;
> struct msi_desc *entry;
> - int i;
> + int cpu = -1, i;
>
> for (i = 0; i < nvec; i++) {
> + if (dev->irq_affinity) {
> + cpu = cpumask_next(cpu, dev->irq_affinity);
> + if (cpu >= nr_cpu_ids)
> + cpu = cpumask_first(dev->irq_affinity);
> + mask = cpumask_of(cpu);
> + }
> +
> entry = alloc_msi_entry(&dev->dev);
> if (!entry) {
> if (!i)
> @@ -699,6 +708,7 @@ static int msix_setup_entries(struct pci_dev *dev, void __iomem *base,
> entry->msi_attrib.default_irq = dev->irq;
> entry->mask_base = base;
> entry->nvec_used = 1;
> + entry->affinity = mask;
>
> list_add_tail(&entry->list, dev_to_msi_list(&dev->dev));
> }
> @@ -1176,12 +1186,20 @@ int pci_alloc_irq_vectors(struct pci_dev *dev, unsigned int min_vecs,
> {
> unsigned int vecs, i;
> u32 *irqs;
> + int ret;
>
> max_vecs = min(max_vecs, pci_nr_irq_vectors(dev));
>
> + ret = irq_create_affinity_mask(&dev->irq_affinity, &max_vecs);
dev->irq_affinity = irq_create_affinity_mask(&max_vecs); ?
> + if (ret)
> + return ret;
> + if (max_vecs < min_vecs)
> + return -ENOSPC;
irq_create_affinity_mask() should be called after MSI-X/MSI is enabled,
because we do not know number of vectors before the range functions
returned that number.
Since affinity masks is a function of number of vectors and CPU topology
the resulting masks might turn out suboptimal in general case (and
this code supposed to be general, right?).
I.e irq_create_affinity_mask() could decide "per-first-sibling" spreading
given number of available vectors, but only a subset of MSI vectors
were actually allocated. For that subset "per-core" affinity mask could
have been initialized, but we will still go with "per-first-sibling".
> + ret = -ENOMEM;
> irqs = kcalloc(max_vecs, sizeof(u32), GFP_KERNEL);
> if (!irqs)
> - return -ENOMEM;
> + goto out_free_affinity;
>
> if (!(flags & PCI_IRQ_NOMSIX)) {
> vecs = pci_enable_msix_range_wrapper(dev, irqs, min_vecs,
> @@ -1208,6 +1226,10 @@ int pci_alloc_irq_vectors(struct pci_dev *dev, unsigned int min_vecs,
> done:
> dev->irqs = irqs;
> return vecs;
> +out_free_affinity:
> + kfree(dev->irq_affinity);
> + dev->irq_affinity = NULL;
> + return ret;
> }
> EXPORT_SYMBOL(pci_alloc_irq_vectors);
>
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 84a20fc..f474611 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -321,6 +321,7 @@ struct pci_dev {
> */
> unsigned int irq;
> unsigned int *irqs;
> + struct cpumask *irq_affinity;
> struct resource resource[DEVICE_COUNT_RESOURCE]; /* I/O and memory regions + expansion ROMs */
>
> bool match_driver; /* Skip attaching driver */
> --
> 2.1.4
>
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