On Fri, Jan 04, 2019 at 08:53:24AM -0700, Keith Busch wrote: > On Fri, Jan 04, 2019 at 03:21:07PM +0800, Ming Lei wrote: > > Thinking about the patch further: after pci_alloc_irq_vectors_affinity() > > is returned, queue number for non-polled queues can't be changed at will, > > because we have to make sure to spread all CPUs on each queue type, and > > the mapping has been fixed by pci_alloc_irq_vectors_affinity() already. > > > > So looks the approach in this patch may be wrong. > > That's a bit of a problem, and not a new one. We always had to allocate > vectors before creating IRQ driven CQ's, but the vector affinity is > created before we know if the queue-pair can be created. Should the > queue creation fail, there may be CPUs that don't have a queue. > > Does this mean the pci msi API is wrong? It seems like we'd need to > initially allocate vectors without PCI_IRQ_AFFINITY, then have the > kernel set affinity only after completing the queue-pair setup. I think this kind of API style(two stages) is more clean, and error-immune. - pci_alloc_irq_vectors() is only for allocating irq vectors - pci_set_irq_vectors_affnity() is for spreading affinity at will Thanks, Ming
