WARNING - OLD ARCHIVES

This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
   
 
 
Xen 
 
Home Products Support Community News
 
   
 

xen-devel

RE: [Xen-devel][PATCH 0/5] Add cpufreq pwr mgmt to Xen

To: "Langsdorf, Mark" <mark.langsdorf@xxxxxxx>, "Liu, Jinsong" <jinsong.liu@xxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: RE: [Xen-devel][PATCH 0/5] Add cpufreq pwr mgmt to Xen
From: "Tian, Kevin" <kevin.tian@xxxxxxxxx>
Date: Fri, 16 May 2008 12:59:16 +0800
Cc: "Nakajima, Jun" <jun.nakajima@xxxxxxxxx>
Delivery-date: Thu, 15 May 2008 22:00:57 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxx
In-reply-to: <6453C3CB8E2B3646B0D020C112613273C5AB7B@xxxxxxxxxxxxxxxxx>
List-help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-id: Xen developer discussion <xen-devel.lists.xensource.com>
List-post: <mailto:xen-devel@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
References: <9D7649D18729DE4BB2BD7B494F7FEDC201400CB4@xxxxxxxxxxxxxxxxxxxxxxxxxxxx> <6453C3CB8E2B3646B0D020C112613273C5AB7B@xxxxxxxxxxxxxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
Thread-index: Aci0psbAJyAAXqNnQsOQlsmPt5l5EgCLz8lQAA4PRwA=
Thread-topic: [Xen-devel][PATCH 0/5] Add cpufreq pwr mgmt to Xen
>From: Langsdorf, Mark [mailto:mark.langsdorf@xxxxxxx] 
>Sent: 2008年5月16日 5:55
>
>> The following patchset is to add processor P state power management
>> support to Xen X86.
>
>Is there any way to determine what frequencies the
>CPU is running at now?  I think I have support for
>the AMD Architectural P-state driver working now,
>but it would be nice if there was a better way to
>test that it's working.
>

Mark, the efficient way to check current freq is cpu specific.
ACPI defines a way to read PERF_STATUS and then
compare to _PSS status field as confirmation whether the
transition succeeds. Corresponding MSR in Intel are
IA32_PERF_STATUS upon which cpufreq driver exacts to
compare freq table for actual value. As hardware coordination
is active, above value doesn't reflect the actual freq. Thus
there're a new MSR pair (MPERF/APERF) on Intel processors
to report the actual freq. You can check get_cur_freq_on_cpu
for all possible ways. I can't tell for AMD cpus but I guess
similar MSRs may also exist in your case.

Thanks,
Kevin

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel

<Prev in Thread] Current Thread [Next in Thread>