On Tue, May 24, 2016 at 6:42 PM, Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote: > > > On 24/05/2016 04:09, Wincy Van wrote: >> The server side use kernel spin-lock frequently, NT kernel is >> different with Linux, >> it will raise TPR to 2 if a spin-lock acquired. We also see that the >> context switch >> rate on HOST is very high w/o APICv, and GUEST ping will raise up to ~2000ms, >> even lost network respond. I think the frequently _tpr_below_threshold_ and >> the _irq_window_ vmexits slow down the GUEST, and the interrupt of guest will >> have a huge latency. >> >> With APICv, the guest will run normally. > > What actually makes a difference here is the self-IPI acceleration, not > simply raising the TPR. Windows does a self-IPI when you schedule a DPC. > OK, I see.. Thanks for your explanation :-) Wincy -- 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
