On Wed, Mar 27, 2019 at 06:36:35PM +0800, Dongli Zhang wrote: > When tag_set->nr_maps is 1, the block layer limits the number of hw queues > by nr_cpu_ids. No matter how many hw queues are used by virtio-scsi, as it > has (tag_set->nr_maps == 1), it can use at most nr_cpu_ids hw queues. > > In addition, specifically for pci scenario, when the 'num_queues' specified > by qemu is more than maxcpus, virtio-scsi would not be able to allocate > more than maxcpus vectors in order to have a vector for each queue. As a > result, it falls back into MSI-X with one vector for config and one shared > for queues. > > Considering above reasons, this patch limits the number of hw queues used > by virtio-scsi by nr_cpu_ids. > > Signed-off-by: Dongli Zhang <dongli.zhang@xxxxxxxxxx> > --- > drivers/scsi/virtio_scsi.c | 1 + > 1 file changed, 1 insertion(+) Reviewed-by: Stefan Hajnoczi <stefanha@xxxxxxxxxx>
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