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] Xen spinlock questions

To: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Subject: Re: [Xen-devel] Xen spinlock questions
From: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
Date: Fri, 15 Aug 2008 10:12:39 -0700
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
Delivery-date: Fri, 15 Aug 2008 10:18:15 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <C4CB3CA8.26026%keir.fraser@xxxxxxxxxxxxx>
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: <C4CB3CA8.26026%keir.fraser@xxxxxxxxxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
User-agent: Thunderbird 2.0.0.16 (X11/20080723)
Keir Fraser wrote:
> On 15/8/08 13:15, "Jan Beulich" <jbeulich@xxxxxxxxxx> wrote:
>
>   
>> I can't really explain the results of testing with this version of the patch:
>> While the number of false wakeups got further reduced by somewhat
>> less than 20%, both time spent in the kernel and total execution time
>> went up (8% and 4% respectively) compared to my original (and from
>> all I can tell worse) version of the patch. Nothing else changed as far as
>> I'm aware.
>>     
>
> That is certainly odd. Presumably consistent across a few runs? I can't
> imagine where extra time would be being spent though...
>   

2 locked instructions in vcpu_unblock() when using polling?  Doesn't
seem like 8%-worth of time though.

    J

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