Author: jimharris
Date: Wed Apr 8 21:46:18 2015
New Revision: 281280
URL: https://svnweb.freebsd.org/changeset/base/281280
Log:
nvme: fall back to a smaller MSI-X vector allocation if necessary
Previously, if per-CPU MSI-X vectors could not be allocated,
nvme(4) would fall back to INTx with a single I/O queue pair.
This change will still fall back to a single I/O queue pair, but
allocate MSI-X vectors instead of reverting to INTx.
MFC after: 1 week
Sponsored by: Intel
Modified:
head/sys/dev/nvme/nvme_ctrlr.c
Modified: head/sys/dev/nvme/nvme_ctrlr.c
==============================================================================
--- head/sys/dev/nvme/nvme_ctrlr.c Wed Apr 8 21:10:13 2015
(r281279)
+++ head/sys/dev/nvme/nvme_ctrlr.c Wed Apr 8 21:46:18 2015
(r281280)
@@ -1144,9 +1144,17 @@ nvme_ctrlr_construct(struct nvme_control
/* One vector per IO queue, plus one vector for admin queue. */
num_vectors = ctrlr->num_io_queues + 1;
- if (pci_msix_count(dev) < num_vectors) {
+ /*
+ * If we cannot even allocate 2 vectors (one for admin, one for
+ * I/O), then revert to INTx.
+ */
+ if (pci_msix_count(dev) < 2) {
ctrlr->msix_enabled = 0;
goto intx;
+ } else if (pci_msix_count(dev) < num_vectors) {
+ ctrlr->per_cpu_io_queues = FALSE;
+ ctrlr->num_io_queues = 1;
+ num_vectors = 2; /* one for admin, one for I/O */
}
if (pci_alloc_msix(dev, &num_vectors) != 0) {
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