Jan Kiszka wrote: > Hi, > > did anyone recently tried current KVM for Intel over some real-time > Linux? I'm seeing more than 500 us latency peaks on the host, > specifically during VM startup. This applies to both 2.6.29.6-rt23 and > Xenomai/I-pipe. For -rt, I both tried the included (patched) KVM modules > as well as kvm.git head with some additionally required -rt fixes. > Xenomai ran over a 2.6.30 kernel with my own KVM-enabler patch. > > Early instrumentation actually points to the guest exit itself: I added > markers right before and after the assembly part of vmx_vcpu_run, and > further instrumentation reports that the next host APIC tick should go > off right inside guest mode. But KVM leaves the switching part 500 us > too late in that case - as if guest exit on external IRQs was disabled. > > Will debug this further, but I'm also curious to hear other user > experiences. > > Jan > > Hi Jan, Did you try to run with latency-tracer enabled? If not, this may pinpoint the source for you. Regards, -Greg
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