Dong, Eddie wrote: > Avi Kivity wrote: > >> Dong, Eddie wrote: >> >>> Add back pending irqs for apic timer to get precise guest >>> APIC timer interrupt. >>> >>> >> Can you explain the problem and the solution in more detail? >> > > Today guest sleep 10 seconds only get about 5-6 seconds in host time. > A design philosiphy in various VMM is that guest wall clock should catch > up host wall clock. > > The reason (partly) is that A VM may be descheduled, while the host time > is still going. For periodic timer like APIC timer, guest expect to see > certain amount of interrupt that stands for the time passed (host time). > In previous > APIC timer virtualization policy, we inject an IRQ to APIC when a period > of host time is passed, but the guest may not take it if it is > descheduled. > In that way the previous irq in APIC will be overwritten by next > injection from fire of > host hrtimer. In that way guest get less amount of APIC timer IRQ. > > This patch keep track of the pending irqs and inject them back to guest > eventually > even the guest may be descheduled. This is also what we did in Xen. > BTW, This policy will also be applied to future kernel PIT, I just do it > step by step. > >
I see. We have something like that in userspace (called the time-drift-fix, or tdf). Will look at the patch now. -- error compiling committee.c: too many arguments to function ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
