On Thu, Nov 04, 2010 at 02:15:16PM +0800, Sheng Yang wrote: > Here is the latest series of MSI-X mask supporting patches. > > The bigest change from last version is, in order to reduce the complexity, I > moved all mask bit operation to kernel, including disabled entries. This > addressed two concerns: > 1. KVM and QEmu each own a part of mask bit operation. > 2. QEmu need accessing the real hardware to get the mask bit information. > > So now QEmu have to use kernel API to get mask bit information. Though it > would be slower than direct accessing the real hardware's MMIO, the direct > accessing is unacceptable beacuse in fact the host OS own the device. The host > OS can access the device without notifying the guest(and don't need to do so). > Userspace shouldn't penetrate the host OS layer to directly operate the real > hardware, otherwise would cause guest confusion. > > Also I discard the userspace mask operation as well, after showed the > performance number. > > This version also removed the capability enabling mechanism. Because we want > to use the struct kvm_assigned_msix_entry with new IOCTL, so there is no > compatible issue. > > Please review. And I would run more test with current patch. So far so good. It would be good to know where the performance issue is with the entire implementation of mask bit in QEMU. http://www.mail-archive.com/kvm@xxxxxxxxxxxxxxx/msg42652.html. All you mentioned in the past was "there was high CPU utilization when running in QEMU" and decided to start implementing in kernel. But AFAICS you did not really look into where the problem was... -- 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
