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nvme: fall back to a smaller MSI-X vector allocation if necessary

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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
This commit is contained in:
Jim Harris 2015-04-08 21:46:18 +00:00
parent 8a7ad10169
commit e5ce537999
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=281280
1 changed files with 9 additions and 1 deletions
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10
sys/dev/nvme/nvme_ctrlr.c
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@ -1144,9 +1144,17 @@ nvme_ctrlr_construct(struct nvme_controller *ctrlr, device_t dev)
/* 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) {