On Wed, 26 Jun 2019, Konrad Rzeszutek Wilk wrote: > On Wed, Jun 26, 2019 at 06:16:08PM +0200, Peter Zijlstra wrote: > > On Wed, Jun 26, 2019 at 10:54:13AM -0400, Konrad Rzeszutek Wilk wrote: > > > There were some ideas that Ankur (CC-ed) mentioned to me of using the perf > > > counters (in the host) to sample the guest and construct a better > > > accounting idea of what the guest does. That way the dashboard > > > from the host would not show 100% CPU utilization. > > > > But then you generate extra noise and vmexits on those cpus, just to get > > this accounting sorted, which sounds like a bad trade. > > Considering that the CPUs aren't doing anything and if you do say the > IPIs "only" 100/second - that would be so small but give you a big benefit > in properly accounting the guests. The host doesn't know what the guest CPUs are doing. And if you have a full zero exit setup and the guest is computing stuff or doing that network offloading thing then they will notice the 100/s vmexits and complain. > But perhaps there are other ways too to "snoop" if a guest is sitting on > an MWAIT? No idea. Thanks, tglx
