On Tue, Jul 06, 2021 at 07:42:03AM +0200, Christoph Hellwig wrote:

On Fri, Jul 02, 2021 at 11:05:54PM +0800, Ming Lei wrote:

quoted

blk-mq needs to know if the device uses managed irq, so add one field
to virtio_device for recording if device uses managed irq.

If the driver use managed irq, this flag has to be set so it can be
passed to blk-mq.

I don't think all this boilerplate code make a whole lot of sense.
I think we need to record this information deep down in the irq code by
setting a flag in struct device only if pci_alloc_irq_vectors_affinity
atually managed to allocate multiple vectors and the PCI_IRQ_AFFINITY
flag was set.  Then blk-mq can look at that flag, and also check that
more than one queue is in used and work based on that.

How can blk-mq look at that flag? Usually blk-mq doesn't play with
physical device(HBA).

So far almost all physically properties(segment, max_hw_sectors, ...)
are not provided to blk-mq directly, instead by queue limits abstract.

Thanks,
Ming

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