Bugs item #1900228, was opened at 2008-02-23 10:26 Message generated for change (Comment added) made by glommer You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=893831&aid=1900228&group_id=180599 Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: amd Group: None Status: Open Resolution: None Priority: 6 Private: No Submitted By: stevie1024 (stevie1024) Assigned to: Nobody/Anonymous (nobody) Summary: Time on guest slows down sometimes... Initial Comment: I run kvm version 60 on an linux 2.6.24 kernel on an AMD 64 processor (see below for details). I installed 2 guest machines, one linux and one windows (XP) and started them both. The clocks on both guests are sometimes slowed down. If e.g. I play some youtube clips on the Windows guest, the clock of the Windows guest starts lagging about 15% (time is about 15% slower than host, or real, time). If I cause some load on the linux guest, e.g. with 'tar jcvf test /usr', the clock of this guest also runs about 5% slower. And there's a message in the client syslog saying 'warning: many lost ticks, Your time source seems to be instable or some driver is hogging interupts'. Running e.g. 'tar jcvf test /usr' on the host doesn't have any influence on the guest clocks. I think this is quite a serious bug, as 'ntp' can't compensate for this instability. If I understand correctly ntp can only compensate for clocks that are too slow or too fast by a reasonably fixed (low) percentage. /proc/cpuinfo: processor : 0 vendor_id : AuthenticAMD cpu family : 15 model : 95 model name : AMD Athlon(tm) Processor LE-1600 stepping : 3 cpu MHz : 2204.998 cache size : 1024 KB fpu : yes fpu_exception : yes cpuid level : 1 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 syscall nx mmxext fxsr_opt rdtscp lm 3dnowext 3dnow up rep_good pni cx16 lahf_lm svm extapic cr8_legacy bogomips : 4413.24 TLB size : 1024 4K pages clflush size : 64 cache_alignment : 64 address sizes : 40 bits physical, 48 bits virtual power management: ts fid vid ttp tm stc uname -a: Linux bigbird 2.6.24-1-amd64 #1 SMP Mon Feb 11 13:47:43 UTC 2008 x86_64 GNU/Linux clients were started with: kvm -m 1024 -usb -hda wxp_test.img -net nic,vlan=0 -net user,vlan=0,hostname=wxp-test -boot c -vnc :0 and kvm -m 512 -usb -hda debian_server.img -net nic,vlan=0 -net user,vlan=0,hostname=debian-server -vnc :1 ---------------------------------------------------------------------- Comment By: Glauber de Oliveira Costa (glommer) Date: 2010-06-25 17:01 Message: Specially for windows guests, the option -rt-td-hack may be helpful. For linux guests, if you can run a new enough guest, using a guest with kvmclock can make the clock go in sync . ---------------------------------------------------------------------- Comment By: stevie1024 (stevie1024) Date: 2008-02-23 10:32 Message: Logged In: YES user_id=2017347 Originator: YES I forgot to mention, I think bug 1826080 is related to this, but I think my description is more general. ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=893831&aid=1900228&group_id=180599 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
