Re: DomU freezes in the middle of booting [SOLVED]

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On Apr 12, 2012 9:46 PM, "Konstantin" <[email protected]> wrote:
>
> Hello Pandu,
>
>
> If you mean Tickless System (Dynamic Ticks) as NO_HZ=y so it already
> enabled for me.
>
> I figured out how to solve my problem with DomU. I've changed tsc_mode
> to something different from 0 or 4 and it seems started to work for
> me.
>
> Here is short tsc_mode option description from sample VM config file:
>
>
#----------------------------------------------------------------------------
> #   tsc_mode : TSC mode (0=default, 1=native TSC, 2=never emulate,
3=pvrdtscp)
> #   emulate TSC provides synced TSC for all vcpus, but lose perfomrance.
> #   native TSC leverages hardware's TSC(no perf loss), but vcpu's TSC may
lose
> #    sync due to hardware's unreliable/unsynced TSC between CPUs.
> #   default intelligently uses native TSC on machines where it is safe,
but
> #    switches to emulated if necessary after save/restore/migration
> #   pvrdtscp is for intelligent apps that use special Xen-only
paravirtualized
> #    cpuid instructions to obtain offset/scaling/migration info and
maximize
> #    performance within pools of machines that support the rdtscp
instruction
> tsc_mode=1
>

Ah, glad to hear that.

> BTW, does anybody has NTP server on a virtual machine? ;)
>

Actually, I do. With tickless, the clock drifts around unpredictably, so I
resort to having one of my VMs sync to the NTP pool, while other VMs sync
to that VM.

Rgds,

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<p><br>
On Apr 12, 2012 9:46 PM, &quot;Konstantin&quot; &lt;<a href=3D"mailto:konst=
[email protected]">[email protected]</a>&gt; wrote:<br>
&gt;<br>
&gt; Hello Pandu,<br>
&gt;<br>
&gt;<br>
&gt; If you mean Tickless System (Dynamic Ticks) as NO_HZ=3Dy so it already=
<br>
&gt; enabled for me.<br>
&gt;<br>
&gt; I figured out how to solve my problem with DomU. I&#39;ve changed tsc_=
mode<br>
&gt; to something different from 0 or 4 and it seems started to work for<br=
>
&gt; me.<br>
&gt;<br>
&gt; Here is short tsc_mode option description from sample VM config file:<=
br>
&gt;<br>
&gt; #---------------------------------------------------------------------=
-------<br>
&gt; # =C2=A0 tsc_mode : TSC mode (0=3Ddefault, 1=3Dnative TSC, 2=3Dnever e=
mulate, 3=3Dpvrdtscp)<br>
&gt; # =C2=A0 emulate TSC provides synced TSC for all vcpus, but lose perfo=
mrance.<br>
&gt; # =C2=A0 native TSC leverages hardware&#39;s TSC(no perf loss), but vc=
pu&#39;s TSC may lose<br>
&gt; # =C2=A0 =C2=A0sync due to hardware&#39;s unreliable/unsynced TSC betw=
een CPUs.<br>
&gt; # =C2=A0 default intelligently uses native TSC on machines where it is=
 safe, but<br>
&gt; # =C2=A0 =C2=A0switches to emulated if necessary after save/restore/mi=
gration<br>
&gt; # =C2=A0 pvrdtscp is for intelligent apps that use special Xen-only pa=
ravirtualized<br>
&gt; # =C2=A0 =C2=A0cpuid instructions to obtain offset/scaling/migration i=
nfo and maximize<br>
&gt; # =C2=A0 =C2=A0performance within pools of machines that support the r=
dtscp instruction<br>
&gt; tsc_mode=3D1<br>
&gt;</p>
<p>Ah, glad to hear that.</p>
<p>&gt; BTW, does anybody has NTP server on a virtual machine? ;)<br>
&gt;</p>
<p>Actually, I do. With tickless, the clock drifts around unpredictably, so=
 I resort to having one of my VMs sync to the NTP pool, while other VMs syn=
c to that VM.</p>
<p>Rgds,<br>
 </p>

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