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Old 06-22-2015, 02:47 AM   #1
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Registered: Jun 2011
Posts: 9

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Unhappy KVM trouble width time

hi everyone ,
I have instaled KVM on Fedora (QEMU emulator version 2.1.3 ) virsh (

On kvm created Windows 7 pro server for IP video monitoring , I have trouble with time after 1 minute the clock hurry for 20 second

What i can do ?Now i set up NTP working every 5-7 second but sometimes recorded video have jamming ,Lost 1 -2 second parts

Hardware cpi is 2x Intel(R) Xeon(R) CPU E5620 @ 2.40GHz

I set up timer for <timer name='rtc' tickpolicy='catchup'/>
bcdedit /set {default} USEPLATFORMCLOCK on

don`t help

my config
Old 06-24-2015, 09:45 PM   #2
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Registered: Jan 2009
Location: RHELtopia....
Distribution: Solaris 11.2/Slackware/RHEL/
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Hey Dzaku,

This sounds like a RedHat / KVM bug...
Bug 742736 - Use rtc tickpolicy catchup by default for windows guests

Their solution looks like this.

<clock offset='localtime'>
<timer name='rtc' tickpolicy='catchup'/>
your current configuration
<clock offset='localtime'>
<timer name='rtc' tickpolicy='catchup'/>
<timer name='pit' tickpolicy='delay'/>
<timer name='hpet' present='no'/>
<timer name='hypervclock' present='yes'/>
Admittedly, I'm unsure why a programmable interval timer set to "delay" would impact your real time clock, however it's often helpful to isolate specific calls until you find the one going balls up. So, if left to my own devices I'd probably...
Save your config, strip out all other timer references from the clock element (use the config section from the bug report). See if you can reproduce the problem (we're testing to see if the pit timer interacting with the real time clock is at the heart of the problem). If that works, think about why you need the PIT timer.

If that doesn't work, create a timer as the first entry of the clock element
timer name='platform' tickpolicy='catchup'
As I understand the KVM clock structure, the 'platform' timer establishes policy for all other timers in the VM, so perhaps that will solve your problem.
Sorry I don't have a silver bullet for you, but you live in a boat city in Poland so I'm thinking you appreciate a challenge...

Last edited by dijetlo; 06-24-2015 at 09:47 PM. Reason: 'Clock' ... 'Timer'... it's the same thing, isn't it?


clock, fedora, kvm, qemu, windows 7

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