On 07/02/2012 12:30 PM, Jan Kiszka wrote: > On 2012-07-02 11:18, Michael S. Tsirkin wrote: >> I've been thinking hard about Jan's patches for device >> assignment. Basically while I thought it makes sense >> to make all devices: assignment and not - behave the >> same and use same APIs for injecting irqs, Anthony thinks there is huge >> value in making irq propagation hierarchical and device assignment >> should be special cased. > > On the long term, we will need direct injection, ie. caching, to allow > making it lock-less. Stepping through all intermediate layers will cause > troubles, at least performance-wise, when having to take and drop a lock > at each stop. So we precalculate everything beforehand. Instead of each qemu_irq triggering a callback, calculating the next hop and firing the next qemu_irq, configure each qemu_irq array with a function that describes how to take the next hop. Whenever the configuration changes, recalculate all routes. For device assignment or vhost, we can have a qemu_irq_irqfd() which converts a qemu_irq to an eventfd. If the route calculations determine that it can be serviced via a real irqfd, they also configure it as an irqfd. Otherwise qemu configures a poll on this eventfd and calls the callback when needed. -- error compiling committee.c: too many arguments to function -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
