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 <hch@xxxxxx>
---
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
--
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