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

[Xen-devel] Re: [PATCH 00/20] x86: ticket lock rewrite and paravirtualiz

To: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
Subject: [Xen-devel] Re: [PATCH 00/20] x86: ticket lock rewrite and paravirtualization
From: "H. Peter Anvin" <hpa@xxxxxxxxx>
Date: Mon, 15 Nov 2010 12:03:27 -0800
Cc: Xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>, Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxx>, Peter Zijlstra <peterz@xxxxxxxxxxxxx>, Srivatsa Vaddagiri <vatsa@xxxxxxxxxxxxxxxxxx>, Linux Kernel Mailing List <linux-kernel@xxxxxxxxxxxxxxx>, Jan Beulich <JBeulich@xxxxxxxxxx>, Linux Virtualization <virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx>, Avi Kivity <avi@xxxxxxxxxx>
Delivery-date: Mon, 15 Nov 2010 12:05:35 -0800
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <4CE1915F.60507@xxxxxxxx>
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: <cover.1288794124.git.jeremy.fitzhardinge@xxxxxxxxxx> <4CDDBBD3.5050903@xxxxxxxxx> <4CDDBCE4.80906@xxxxxxxx> <4CDDBDB5.8000800@xxxxxxxxx> <4CE1915F.60507@xxxxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
User-agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.12) Gecko/20101027 Fedora/3.1.6-1.fc13 Thunderbird/3.1.6
On 11/15/2010 12:00 PM, Jeremy Fitzhardinge wrote:
> 
> Another approach I discussed with PeterZ and Mathieu is to steal the LSB
> of the ticket counters (halving the max CPU count) to use as a "there is
> someone in slowpath waiting on this lock".  But I haven't spent the time
> to work out an algorithm to maintain that flag (or flags, since there
> are bits available) in a correct and efficient way.
> 

Definitely worth pondering.

        -hpa


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

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