Hi sagi Thanks for your kindly response.
On 03/01/2018 05:28 PM, Sagi Grimberg wrote: > >> Note that we originally allocates irqs this way, and Keith changed >> it a while ago for good reasons. So I'd really like to see good >> reasons for moving away from this, and some heuristics to figure >> out which way to use. E.g. if the device supports more irqs than >> I/O queues your scheme might always be fine. > > I still don't understand what this buys us in practice. Seems redundant > to allocate another vector without any (even marginal) difference. > When the adminq is free, ioq0 irq completion path has to invoke nvme_irq twice, one for itself, one for adminq completion irq action. We are trying to save every cpu cycle across the nvme host path, why we waste nvme_irq cycles here. If we have enough vectors, we could allocate another irq vector for adminq to avoid this. Sincerely Jianchao
