Anthony Liguori wrote: > Ben-Ami Yassour wrote: >> On Wed, 2008-07-16 at 17:36 +0300, Avi Kivity wrote: >> >>> Ben-Ami Yassour wrote: >>> >>>> In last few tests that we made with PCI-passthrough and VT-d using >>>> iperf, we were able to get the same throughput as on native OS >>>> with a 1G NIC >>>> >>> Excellent! >>> >>> >>>> (with higher CPU utilization). >>>> >>>> >>> How much higher? >>> >> >> Here are some numbers for running iperf -l 1M: >> >> e1000 NIC (behind a PCI bridge) >> Bandwidth (Mbit/sec) CPU utilization >> Native OS 771 18% >> Native OS with VT-d 760 18% >> KVM VT-d 390 95% >> KVM VT-d with direct mmio 770 84% >> KVM emulated 57 100% >> > > What about virtio? Also, which emulated is this? > > That CPU utilization is extremely high and somewhat illogical if > native w/vt-d has almost no CPU impact. Have you run oprofile yet or > have any insight into where CPU is being burnt? > > What does kvm_stat look like? I wonder if there are a large number of > PIO exits. What does the interrupt count look like on native vs. KVM > with VT-d? >
e1000 NIC doesn't use PIO. Randy (Weidong)
