From mboxrd@z Thu Jan  1 00:00:00 1970
From: Anthony Liguori <anthony@codemonkey.ws>
Subject: Re: Houston, we have May 15, 1953 (says guest when host uses cpufreq,
 and dies)
Date: Wed, 18 Feb 2009 10:02:57 -0600
Message-ID: <499C3131.3030601@codemonkey.ws>
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Cc: kvm@vger.kernel.org
To: Tomasz Chmielewski <mangoo@wpkg.org>
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Tomasz Chmielewski wrote:
> Is using cpufreq (i.e. with ondemand governor) on KVM host safe for 
> guests?
>
> I enabled cpufreq on the host, it scaled down the host CPU (Dual-Core 
> AMD Opteron(tm) Processor 2212) to 1 GHz from 2 GHz.

Not with your processor.  Intel processors should be fine and any AMD 
processor that's Barcelona/Phenom or newer.

Regards,

Anthony Liguori

> Guest (using 1 CPU) was still showing that it has a 2 GHz CPU in 
> /proc/cpuinfo (I guess this value is read only once, when booting).
>
> After about 2 hours I started "date" on the guest - it showed that 
> it's year *1953*, after which I couldn't start any other command (the 
> guest was technically alive - SSH connection to it didn't die - but I 
> couldn't do anything).
>
> # date
> Wed Feb 18 13:07:17 CET 2009
>
> [let's wait ~2 hours]
>
>
> # date
> Fri May 15 10:13:14 CET 1953
> # date
> ^C^Z
> [could not interrupt]
>
>
> Is it expected behaviour? Is it correct behaviour?
>
>