On Tue, Nov 08, 2016 at 04:08:51PM +0100, Hannes Reinecke wrote: > The use-case here is that one needs to feed the MSI-X index into the driver > command structure. While we can extract that number trivially with scsi-mq, > but for scsi-sq we don't have such means.
> The main impetus of this RFC is to figure out if such a function would have > a chance of getting upstream, or if I have to continue use cpumaps in the > drivers. There should be no need for a cpumap, nor should there be any need for a lookup. Driver will need the vector index for some admin ops, but it can store it in it's driver-private queue structure (e.g. take a look at the cq_vector field in NVMe). Drivers really should not need this during I/O, but if for some weird reason they do that driver specific field is trivially reachable through the hw_ctx which gets passed to ->queue_rq.
