On Mon, Nov 13, 2017 at 06:05:59PM +0800, Quan Xu wrote: > From: Yang Zhang <yang.zhang.wz@xxxxxxxxx> > > Some latency-intensive workload have seen obviously performance > drop when running inside VM. The main reason is that the overhead > is amplified when running inside VM. The most cost I have seen is > inside idle path. Meaning an VMEXIT b/c it is an 'halt' operation ? And then going back in guest (VMRESUME) takes time. And hence your latency gets all whacked b/c of this? So if I understand - you want to use your _full_ timeslice (of the guest) without ever (or as much as possible) to go in the hypervisor? Which means in effect you don't care about power-saving or CPUfreq savings, you just want to eat the full CPU for snack? > > This patch introduces a new mechanism to poll for a while before > entering idle state. If schedule is needed during poll, then we > don't need to goes through the heavy overhead path. Schedule of what? The guest or the host?
