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/
Home Products Support Community News


RE: [Xen-devel] [RFC] Physical hot-add cpus and TSC

To: Dan Magenheimer <dan.magenheimer@xxxxxxxxxx>, Keir Fraser <keir.fraser@xxxxxxxxxxxxx>, "Xen-Devel (xen-devel@xxxxxxxxxxxxxxxxxxx)" <xen-devel@xxxxxxxxxxxxxxxxxxx>, Ian Pratt <Ian.Pratt@xxxxxxxxxxxxx>
Subject: RE: [Xen-devel] [RFC] Physical hot-add cpus and TSC
From: "Jiang, Yunhong" <yunhong.jiang@xxxxxxxxx>
Date: Tue, 1 Jun 2010 09:40:44 +0800
Accept-language: en-US
Acceptlanguage: en-US
Delivery-date: Mon, 31 May 2010 18:42:09 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <87987703-973e-4d24-ba9f-091a97ed3384@default>
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/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
References: <789F9655DD1B8F43B48D77C5D30659731E78D370@xxxxxxxxxxxxxxxxxxxxxxxxxxxx> <C823EF64.1603B%keir.fraser@xxxxxxxxxxxxx> <789F9655DD1B8F43B48D77C5D30659731E78D500@xxxxxxxxxxxxxxxxxxxxxxxxxxxx> <3c99c55d-68ce-4150-b895-72fda1ff3b89@default> <789F9655DD1B8F43B48D77C5D30659731E78D89D@xxxxxxxxxxxxxxxxxxxxxxxxxxxx> <26342d1d-2141-4fb1-94ac-a398d7f553d6@default> <789F9655DD1B8F43B48D77C5D30659731E78DA70@xxxxxxxxxxxxxxxxxxxxxxxxxxxx> <2d0b4e25-6fa9-4d66-9efe-a1b9e27612f5@default 789F9655DD1B8F43B48D77C5D30659731E7EC349@xxxxxxxxxxxxxxxxxxxxxxxxxxxx> <87987703-973e-4d24-ba9f-091a97ed3384@default>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
Thread-index: AcsBIbYYroh44UcvTpeAX1l4K1iXngABlzrg
Thread-topic: [Xen-devel] [RFC] Physical hot-add cpus and TSC
Yes, I'm confused by this also.
It will takes to this weekend so that I can try it again.


>-----Original Message-----
>From: Dan Magenheimer [mailto:dan.magenheimer@xxxxxxxxxx]
>Sent: Tuesday, June 01, 2010 8:31 AM
>To: Jiang, Yunhong; Keir Fraser; Xen-Devel (xen-devel@xxxxxxxxxxxxxxxxxxx); Ian
>Subject: RE: [Xen-devel] [RFC] Physical hot-add cpus and TSC
>> BTW, I notice one more thing, when system booting w/o hotplug, the warp
>> is 0. However, after I return back after weekend, I noticed the warp is
>> 182. Because I did the hotplug action before getting the warp, I'm not
>> sure if it's caused by the hotplug action, or the system TSC will drift
>> very slowly.
>>  (XEN) TSC marked as reliable, warp = 182 (count=2)
>Hmmm... I'm much more worried about this case and would
>like to understand this better.  If this is reproducible
>on real-world QPI systems, and there is no way to a priori
>determine that "this is a system where even though the
>Invariant TSC bit is set, this system may drift", then
>there is no way Invariant TSC can be exposed to a guest.
>/me can hear Jeremy biting his tongue hard to avoid
>saying "I told you so". ;-)

Xen-devel mailing list