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RE: RE: [Xen-devel] AMD P-States not recognized for Xen 3.3 and 3.4


  • To: "Carsten Schiers" <carsten@xxxxxxxxxx>, "Niraj Tolia" <ntolia@xxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>
  • From: "Langsdorf, Mark" <mark.langsdorf@xxxxxxx>
  • Date: Tue, 13 Jan 2009 11:52:01 -0600
  • Cc:
  • Delivery-date: Tue, 13 Jan 2009 09:52:43 -0800
  • List-id: Xen developer discussion <xen-devel.lists.xensource.com>
  • Thread-index: AclxoOdlxEbb1ZPJTDqWkms58hLurwEBdohg
  • Thread-topic: RE: [Xen-devel] AMD P-States not recognized for Xen 3.3 and 3.4

> OK, I have found the change and ported it into the 2.6.18-xen-3.1-2
> waldi kernel. Fortunately, the Debian Xen 3.2.1 Hypervisor from Lenny,
> which is used by my dsitribution (c't-Server), already implements the
> xenpf_cpuidletime hypercall #53, which is needed. Some changes here 
> and there where necessary, too.
> 
> Now, when setting the ondemand govenor, the system behaves as 
> expected.
> 
> Still (as with userspace govenors), there are 
> 
>   - powernow-k8: error - out of sync, fix 0xd 0x2, vid 0xe 0x16
>   - Timer ISR/0: Time went backwards: delta=
> 
> messages, when the p-states are changed. 4050e, as already mentioned,
> dual-core, single socket.
> 
> Can I safely ignore them or do I have to take care somewhere...?

The out of sync errors are occurring because when you
perform a frequency change, the kernel's record of what
the fid and should be for that CPU are not matching
what it is reading from the physical CPU's MSRs.

I thought Keir and I had narrowed that problem down to
an issue in the implementation of VCPU pinning and fixed
it.  Do you have all of the following change sets?

http://xenbits.xensource.com/linux-2.6.18-xen.hg?rev/a37a8c474d8b
http://xenbits.xensource.com/linux-2.6.18-xen.hg?rev/98de2b149423
http://xenbits.xensource.com/linux-2.6.18-xen.hg?rev/7aaec9c0a213
http://xenbits.xensource.com/linux-2.6.18-xen.hg?rev/8a407c41dfb0
http://xenbits.xensource.com/xen-unstable.hg?rev/2477e94450aa
http://xenbits.xensource.com/xen-unstable.hg?rev/c05ec22a9106
http://xenbits.xensource.com/xen-unstable.hg?rev/ddc9e6b2babb
http://xenbits.xensource.com/linux-2.6.18-xen.hg?rev/fc406f9e9a0a
http://xenbits.xensource.com/linux-2.6.18-xen.hg?rev/922fc4040264
http://xenbits.xensource.com/linux-2.6.18-xen.hg?rev/ba918cb2cf75
http://xenbits.xensource.com/staging/xen-unstable.hg?rev/136f80d2195
http://xenbits.xensource.com/xen-unstable.hg?rev/21532468020b
http://xenbits.xensource.com/linux-2.6.18-xen.hg?rev/26e1e96bd46a 

-Mark Langsdorf
Operating System Research Center
AMD


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