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Re: [Xen-users] cpu frequency scaling in domUs
- To: "Tian, Kevin" <kevin.tian@xxxxxxxxx>, xen-users@xxxxxxxxxxxxxxxxxxx
- From: "Vahid Kazempour" <kazempour@xxxxxxxxx>
- Date: Mon, 28 Jul 2008 13:38:19 -0700
- Cc:
- Delivery-date: Mon, 28 Jul 2008 13:38:56 -0700
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Yeah, I think it is doable with a tiny driver. Thanks for your email. -- Vahid, On Sun, Jul 27, 2008 at 6:43 PM, Tian, Kevin <kevin.tian@xxxxxxxxx> wrote:
Do you want to add this feature to upstream as a clean
feature, or
only target for some in-house experiment? If the latter, I
don't think
that fake ACPI table is necessary, which involves more
effort.
Actually you can just write a tiny cpufreq driver in domU,
which
simply uses hypercall to communicate with HV directly and
is
simply straightforward.
Thanks,
Kevin
From: Vahid Kazempour
[mailto:kazempour@xxxxxxxxx] Sent: 2008å7æ27æ 4:13 To:
Tian, Kevin Subject: Re: [Xen-users] cpu frequency scaling in
domUs
Is it possible to fake ACPI table in PV domain too? I'm
going to use it as a scheduler hint. So, I need it to work in domUs (both PV
and HVM domains). Is it possible to create a frontend driver which provides
this feature in domUs? Thanks -- Vahid
2008/7/24 Tian, Kevin <kevin.tian@xxxxxxxxx>
If domU
means PV domain in your mail, there's even no ACPI table
exposed
to PV
domain. HVM domain has one faked by Qemu. Also the value to
expose
a
virtual cpufreq feature is still unclear. Some papers discuss usage as
scheduler hint or help real power, but none gets into real product
yet.
Thanks
Kevin
Hi,
I've recently installed xen-3.2.1 on my AMD
Sempron(tm) machine. It runs gentoo 2.6.21 as dom0 and cpu frequency
scaling works in dom0. But inside a domU, cpu frequency scaling is not
working. By checking the boot log in domU I found that domU is unable
to load the powernow driver: "powernow-k8: BIOS error - no PSB or ACPI
_PSS objects" I wonder if it is possible to have cpu frequency scaling
support inside domUs?
--
Vahid
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