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] Re: [PATCH] CPUIDLE: revise tsc-save/restore toavoid big

To: Jan Beulich <jbeulich@xxxxxxxxxx>
Subject: RE: [Xen-devel] Re: [PATCH] CPUIDLE: revise tsc-save/restore toavoid big tsc skew between cpus
From: "Wei, Gang" <gang.wei@xxxxxxxxx>
Date: Tue, 16 Dec 2008 16:09:34 +0800
Accept-language: en-US
Acceptlanguage: en-US
Cc: "Tian, Kevin" <kevin.tian@xxxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>, Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Delivery-date: Tue, 16 Dec 2008 00:10:24 -0800
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <49476E25.76E4.0078.0@xxxxxxxxxx>
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: <8FED46E8A9CA574792FC7AACAC38FE7701C7C99F09@xxxxxxxxxxxxxxxxxxxxxxxxxxxx> <C56C2FFC.203C4%keir.fraser@xxxxxxxxxxxxx> <8FED46E8A9CA574792FC7AACAC38FE7701C7DB4EF3@xxxxxxxxxxxxxxxxxxxxxxxxxxxx> <49476E25.76E4.0078.0@xxxxxxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
Thread-index: AclfVFDXtAoUHV2SRn6E8/pS0DOAXwAAF2Uw
Thread-topic: [Xen-devel] Re: [PATCH] CPUIDLE: revise tsc-save/restore toavoid big tsc skew between cpus
On Tuesday, December 16, 2008 4:00 PM, Jan Beulich wrote:
>>>> "Wei, Gang" <gang.wei@xxxxxxxxx> 16.12.08 03:26 >>>
>> Below 't' key outputs are gotten in the extreme case: pin all dom0 & guest
>> vcpus on cpu1 & execute cmd 'while true; do a=1; done' within one guest. The
>> largest stime skew is ~40us, largest cycles skew is ~100,000 ticks(~40us).
>> The normal idle case skew is quite small (~xxxns).  
>> 
>> (XEN) Synced stime skew: max=39662ns avg=8038ns samples=850 current=326ns
>> (XEN) Synced cycles skew: max=100475 avg=20368 samples=850 current=825 ...
>> (XEN) Synced stime skew: max=39750ns avg=16958ns samples=3954 current=30667ns
>> (XEN) Synced cycles skew: max=100708 avg=42967 samples=3954 current=77696 ...
>> (XEN) Synced stime skew: max=39750ns avg=17318ns samples=4544 current=22981ns
>> (XEN) Synced cycles skew: max=100708 avg=43880 samples=4544 current=58225
> 
> Is the average continuing to grow over larger periods of time? I would have
> expected it to converge rather than increase as a proof of it being a long
> term solution.

The average looks converge in my box. We can do more tests after it get in.

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

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