On 07/04/2012 01:42 PM, Michael S. Tsirkin wrote: > On Mon, Jul 02, 2012 at 12:43:48PM +0300, Avi Kivity wrote: >> 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. > > This is more or less what I had in mind and what Anthony objects to. Can you post an interface that supports this? Then we can see exactly what is objectionable. -- 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
