On Sun, Apr 22, 2018 at 08:49:06AM +0800, Wanpeng Li wrote:
2018-04-22 0:30 GMT+08:00 Anthoine Bourgeois <anthoine.bourgeois@xxxxxxxxxxxxxxx>:Since the commit "8003c9ae204e: add APIC Timer periodic/oneshot mode VMX preemption timer support", a Windows 10 guest has some erratic timer spikes after few hours. As the uptime of the VM grows the spikes are larger. Here the results on a 150000 times 1ms timer without any load: Before 8003c9ae204e | After 8003c9ae204e Max 1834us | 86000us Mean 1100us | 1021us Deviation 59us | 149us Here the results on a 150000 times 1ms timer with a cpu-z stress test: Before 8003c9ae204e | After 8003c9ae204e Max 32000us | 140000us Mean 1006us | 1997us Deviation 140us | 11095usIn your testing, preemption_timer kvm_intel parameter is N, right? In addition, could you post the testcase?
The preemption_timer is set to Y. The testcase is an windows app that stream sound. The kernel upgrade trigger lots of sound crackling that get worst over the time. I suspect that there are other side effect on the guest but the sound was the most obvious on our workload. The numbers in the commit message came from a simple test program that loop on a 1ms sleep calls to show more formally the problem. Best regards, Anthoine
