Arjan van de Ven wrote: > On Sun, 2007-02-25 at 07:17 +0200, Avi Kivity wrote: > >> Arjan van de Ven wrote: >> >>>> The easiest thing I can think of is to have the PV disk driver show up >>>> as an actual PCI device and to use a PCI option rom to hijack the >>>> appropriate interrupt. >>>> >>>> >>> yeah that's a good plan. Being a PCI device also helps with the OS >>> userspace knowing which module to load; even if the device itself never >>> gets accessed. >>> >>> >>> >> A problem with pci, at least if you use the pci interrupts, is that your >> interrupt might be shared with another device. I guess a solution is >> not to use pci interrupts, but then we need some mechanism to allocate >> interrupts. >> > > shared interrupts aren't a big deal in Linux. at all. > In fact, sharing all PV interrupts to one number is a performance > enhancement ;) >
If you share a PV interrupt with a non-PV interrupt, then for each PV interrupt you have to check whether the non-PV interrupt fired. That involves at least one expensive vmexit. I agree that sharing PV interrupts is not very expensive (though I don't see why you call it an optimization - if you share 100 interrupts on one line you need to check 100 interrupt sources every time the interrupt fires). -- Do not meddle in the internals of kernels, for they are subtle and quick to panic. ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ kvm-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/kvm-devel
