Ali Saidi wrote: > On Sep 6, 2008, at 4:26 PM, Gabe Black wrote: > > >> There are two major problems with using the DmaPort. First, I'd want >> to >> send the interrupt -now- not when the DMA queuing latency, etc gets >> used >> up. Second, DmaPort will fragment a packet which, while maybe >> necessary >> in some cases, will break the atomicity requirements for the interrupt >> messages and might even make the parts of it get there out of order. >> While it may not -normally- fragment the message, if it does things >> will >> be broken. I would rather not use something where such a large portion >> of its functionality is either not needed or counterproductive. >> > The only time the DMA port will break up the packet is if it's larger > than a cache block. I can't imagine an interrupt message being that > large. With MSI, interrupts don't magically get propagated. They > device still has to arbitrate for the bus. > Ali >
I can't either, but I don't just want to hope that doesn't happen. Also, there will still be arbitration on the bus, but the APIC doesn't have to queue up a DMA transfer to send an IPI since it's not even transferring anything. _______________________________________________ m5-dev mailing list [email protected] http://m5sim.org/mailman/listinfo/m5-dev
