On Jul 12 14:26, Klaus Jensen wrote: > 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. >
In any case, I'm wary about adding this level of kvm-dependence in the device. This wont work on non-kvm platforms any more. I think you should put irqfd on hold and focus on iothreads :)
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