Avi Kivity wrote: > 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. > >
many udev children are exiting; udevd itself is sleeping: > udevd S D5DCDF24 2924 573 372 594 629 535 (NOTLB) > d5dcdf38 00000086 00000002 d5dcdf24 d5dcdf20 00000000 d5dcdefc > d6169f68 > d7db7f68 d5dcdf68 00000001 d5dd7560 c13b8a90 749ae8d2 00000002 > 000326a1 > d5dd7684 c131c700 00000003 d74f8900 892d6946 00000402 ffffffff > 00000000 > Call Trace: > [<c060d2c9>] do_nanosleep+0x3b/0x66 > [<c0439b20>] hrtimer_nanosleep+0x50/0x106 > [<c04397ee>] hrtimer_wakeup+0x0/0x18 > [<c0439c1f>] sys_nanosleep+0x49/0x59 > [<c0404e4c>] syscall_call+0x7/0xb > [<c0600000>] xfrm_state_find+0x49f/0x51e So likely sleeping is screwed up somehow (though only on smp). >> 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. > > Testing shows wrmsr and rdtsc function normally. I'll try pinning the vcpus to cpus and see if that helps. -- error compiling committee.c: too many arguments to function ------------------------------------------------------------------------- SF.Net email is sponsored by: Check out the new SourceForge.net Marketplace. It's the best place to buy or sell services for just about anything Open Source. http://ad.doubleclick.net/clk;164216239;13503038;w?http://sf.net/marketplace _______________________________________________ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
