Messages in this thread | | | Date | Wed, 19 Dec 2007 08:33:39 +0200 | From | Avi Kivity <> | Subject | Re: Guest kernel hangs in smp kvm for older kernels prior to tsc sync cleanup |
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Ingo Molnar wrote: >> While the change mentions that it fixes a time warp bug, it also says >> it should be rare. So clearly kvm smp tsc handing is buggy. >> Ingo/Thomas, (or anybody else), do you have any insight as to what kvm >> can be doing wrong to trigger this behavior? >> > > hm. Those time warps were really small, due to the small imperfections > in the "sync up all CPUs to the same moment and do a WRMSR to clear all > their TSCs" mechanism. I.e. at most a few usec time warps. I really dont > know how that should result in udevd hanging. Can you debug udevd in any > way? > >
Adding debug didn't help. I'll try some sysrq keys to see what the guest thinks is happening.
> so the only thing that KVM might be doing incorrectly here is the > emulation of the WRMSR that clears the TSC of each vcpu? >
By inspection, it is correct. Of course I may be missing something, so I'll write a unit test for it. It should also be much slower than the native wrmsr.
-- error compiling committee.c: too many arguments to function
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