On Jul 9 12:35, Jinhao Fan wrote: > Use irqfd to directly notify KVM to inject interrupts. This is done by > registering a virtual IRQ(virq) in KVM and associate the virq with an > irqfd, so that KVM can directly inject the interrupt when it receives > notification from the irqfd. This approach is supposed to improve > performance because it bypasses QEMU's MSI interrupt emulation logic. > > However, I did not see an obvious improvement of the emulation KIOPS: > > QD 1 4 16 64 > QEMU 38 123 210 329 > irqfd 40 129 219 328 > > I found this problem quite hard to diagnose since irqfd's workflow > involves both QEMU and the in-kernel KVM. > > Could you help me figure out the following questions: > > 1. How much performance improvement can I expect from using irqfd?
This is a level of QEMU/KVM that I am by no means an expert on and I would have to let the broader QEMU community comment on this. > 2. How can I debug this kind of cross QEMU-KVM problems? Not sure how to directly "debug" it, but there is `perf kvm` to get information about what is happing in the kvm subsystem.
signature.asc
Description: PGP signature
