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] PAE issue (32-on-64 work)

To: Joe Bonasera <joe.bonasera@xxxxxxx>
Subject: Re: [Xen-devel] PAE issue (32-on-64 work)
From: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Date: Thu, 19 Oct 2006 19:48:43 +0100
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
Delivery-date: Thu, 19 Oct 2006 12:00:17 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxx
In-reply-to: <4537B45E.9040708@xxxxxxx>
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>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
Thread-index: AcbzrzMscfDI4l+iEduNyQANk04WTA==
Thread-topic: [Xen-devel] PAE issue (32-on-64 work)
User-agent: Microsoft-Entourage/11.2.5.060620
On 19/10/06 6:22 pm, "Joe Bonasera" <joe.bonasera@xxxxxxx> wrote:

>> You should just allocate a page-sized L3 per process and be done with it. A
>> page overhead per process is nothing to be concerned about (clearly the
>> overhead can be even bigger if, for example, you run 4-level tables on
>> x86_64). Recopying the L3 entries every TLB flush will *not* perform well on
>> current Xen.
>> 
> 
> Well we actually don't do complete TLB flushes very often at all, essentially
> only the first time a new L3 entry is created by a running process which
> for most processes means never - as >1Gig processes are rare.
> So it shouldn't matter if they hit one or two slowish flushes.
> 
> Are there any other performance implications to watch out for?

I don't think so. Just remember that PAE L3 entry updates are not fast. We
really expect it only to happen on process creation/destruction (or similar
frequency).

 -- Keir



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

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