Try to grab the MSI-X vectors early and fall back to the shared one before doing tons of allocations.
Signed-off-by: Christoph Hellwig <[email protected]> --- drivers/virtio/virtio_pci_common.c | 52 +++++++++++++++++++------------------- 1 file changed, 26 insertions(+), 26 deletions(-) diff --git a/drivers/virtio/virtio_pci_common.c b/drivers/virtio/virtio_pci_common.c index 03d3a3b..90d7975 100644 --- a/drivers/virtio/virtio_pci_common.c +++ b/drivers/virtio/virtio_pci_common.c @@ -114,6 +114,18 @@ static int vp_setup_msix_vectors(struct virtio_device *vdev, int nvectors) unsigned i; int err = -ENOMEM; + /* Try one vector per queue first. */ + err = pci_alloc_irq_vectors(vp_dev->pci_dev, nvectors, nvectors, + PCI_IRQ_MSIX); + if (err < 0) { + /* Fallback to one vector for config, one shared for queues. */ + err = pci_alloc_irq_vectors(vp_dev->pci_dev, 2, 2, + PCI_IRQ_MSIX); + if (err < 0) + goto error; + nvectors = 2; + } + vp_dev->msix_vectors = nvectors; vp_dev->msix_names = kmalloc(nvectors * sizeof *vp_dev->msix_names, GFP_KERNEL); @@ -129,11 +141,6 @@ static int vp_setup_msix_vectors(struct virtio_device *vdev, int nvectors) GFP_KERNEL)) goto error; - err = pci_alloc_irq_vectors(vp_dev->pci_dev, nvectors, nvectors, - PCI_IRQ_MSIX); - if (err < 0) - goto error; - /* Set the vector used for configuration */ snprintf(vp_dev->msix_names[0], sizeof(*vp_dev->msix_names), "%s-config", name); @@ -149,7 +156,7 @@ static int vp_setup_msix_vectors(struct virtio_device *vdev, int nvectors) goto error; } - return 0; + return nvectors; error: return err; } @@ -242,8 +249,7 @@ void vp_del_vqs(struct virtio_device *vdev) static int vp_find_vqs_msix(struct virtio_device *vdev, unsigned nvqs, struct virtqueue *vqs[], vq_callback_t *callbacks[], - const char * const names[], - bool per_vq_vectors) + const char * const names[]) { struct virtio_pci_device *vp_dev = to_vp_device(vdev); u16 msix_vec; @@ -253,20 +259,16 @@ static int vp_find_vqs_msix(struct virtio_device *vdev, unsigned nvqs, if (!vp_dev->vqs) return -ENOMEM; - if (per_vq_vectors) { - /* Best option: one for change interrupt, one per vq. */ - nvectors = 1; - for (i = 0; i < nvqs; ++i) - if (callbacks[i]) - ++nvectors; - } else { - /* Second best: one for change, shared for all vqs. */ - nvectors = 2; + nvectors = 1; + for (i = 0; i < nvqs; i++) { + if (callbacks[i]) + nvectors++; } err = vp_setup_msix_vectors(vdev, nvectors); - if (err) + if (err < 0) goto error_find; + nvectors = err; allocated_vectors = 1; /* vector 0 is the config interrupt */ for (i = 0; i < nvqs; ++i) { @@ -300,7 +302,11 @@ static int vp_find_vqs_msix(struct virtio_device *vdev, unsigned nvqs, goto error_find; } - if (per_vq_vectors) + /* + * Use a different vector for each queue if they are available, + * else share the same vector for all VQs. + */ + if (nvectors == nvqs + 1) allocated_vectors++; } return 0; @@ -353,15 +359,9 @@ int vp_find_vqs(struct virtio_device *vdev, unsigned nvqs, { int err; - /* Try MSI-X with one vector per queue. */ - err = vp_find_vqs_msix(vdev, nvqs, vqs, callbacks, names, true); - if (!err) - return 0; - /* Fallback: MSI-X with one vector for config, one shared for queues. */ - err = vp_find_vqs_msix(vdev, nvqs, vqs, callbacks, names, false); + err = vp_find_vqs_msix(vdev, nvqs, vqs, callbacks, names); if (!err) return 0; - /* Finally fall back to regular interrupts. */ return vp_find_vqs_intx(vdev, nvqs, vqs, callbacks, names); } -- 2.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-block" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
